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Dt-01/06/2015Comparisons of mechanical and metallurgical properties of GMAW,
FCAW & MCAW weldments of SA516 GR70 steel Material
Pandit Deendayal Petroleum UniversitySchool of Technology ,Mechanical Engineering
Sponsored project of Department ofScience and Technology, New Delhi
1
SupervisorDr. Vishvesh J Badheka, IWEAssociate Professor, Mechanical Engineering DeptSchool of Technology,Pandit Deendayal Petroleum University.
Review Presentation (4th Sem)
Presented ByPritesh J. PrajapatiRo.No- 13RME011PhD Student, PDPU
Content of Presentation
PhD journey Introduction.
GMAW FCAW MCAW
Gap Analyses. Research Plan Proposed Objectives Material Selection. Experimental Procedure. Acknowledgement.
PhD journey Introduction.
GMAW FCAW MCAW
Gap Analyses. Research Plan Proposed Objectives Material Selection. Experimental Procedure. Acknowledgement.
2
SEM WORK DONE DURATION REMARKSem -I Course work
1).Fundamentals of Welding (ME-704)2).Advanced welding processes (ME-701)3).Research Methodology (PET-701)
July-Dec2013
Good
Sem -II Compressive exam and Review ofLiterature survey
Jan-June2013
Good
PhD Journey Enrolled in July 2013
3
Sem -II Compressive exam and Review ofLiterature survey
Jan-June2013
Good
Sem -III Experiment-I July-Dec2014
Very good
Sem -IV Experiment-II Jan-June2015
4
IntroductionGMAW is an electric arc welding process
Fig.1
6Fig.2
FCAW, has a hollow wire with flux in the center, Just as the name states, a FluxCore.
The main difference between MIG welding and FCAW is, FCAW gets its shieldingfrom the flux core, so use at weld outdoors. MIG welding is the way the electrode isshielded from the air.
7The internal components of a metal cored wire are composed chiefly of the alloys,manganese, silicon, and in some cases, nickel. chromium and molybdenum as well as verysmall amounts of arc stabilizers such as sodium and potassium, with the balance being ironpowder.
Gap Analyses Existing literature available in the area of the GMAW and FCAW. Most of research
papers published are the comparison of the solid wire with flux cored wire.
Metal cored wires are the latest development in the area of advances consumables.There is general comparison of characteristics of wires (solid, flux cored and metalcored) are available but effect of different wire on mechanical and metallurgical isnot reported.
Conventionally root run are being filled with the GTAW process because it hasexcellent weld metal properties and subsequently passes with GMAW or SAWdepending on the size of the job.
In addition to the above mentioned detail there is very little research has beencarried out in the area of application of hybrid welds using GMAW, FCAW &MCAW process.
Mechanical and metallurgical properties of solid, flux cored wires ,metal coredwires are also will be compared with hybrid welds.
Existing literature available in the area of the GMAW and FCAW. Most of researchpapers published are the comparison of the solid wire with flux cored wire.
Metal cored wires are the latest development in the area of advances consumables.There is general comparison of characteristics of wires (solid, flux cored and metalcored) are available but effect of different wire on mechanical and metallurgical isnot reported.
Conventionally root run are being filled with the GTAW process because it hasexcellent weld metal properties and subsequently passes with GMAW or SAWdepending on the size of the job.
In addition to the above mentioned detail there is very little research has beencarried out in the area of application of hybrid welds using GMAW, FCAW &MCAW process.
Mechanical and metallurgical properties of solid, flux cored wires ,metal coredwires are also will be compared with hybrid welds.
8
Hybrid Welds
Hybrid welds in which root and filler pass filled with different process.
Hybrid Welding Process
9
Parameters Filler Wire diameter = 1.2mm. Welding Current - 200 A,Voltage - 28 V, Travel Speed 200
Shielding Gas Composition Ar/CO2 =90/10
I II III
ROOT SIDE GMAW FCAW MCAW
FILLER PASSES (OP-1) GMAW FCAW MCAW
Research Plan
FILLER PASSES (OP-1) GMAW FCAW MCAW
FILLER PASSES (OP-2) FCAW GMAW GMAW
FILLER PASSES (OP-3) MCAW MCAW FCAW
SAMPLE ID ROOT RUN FILLER RUN
A GMAW GMAW
B GMAW FCAW
C GMAW MCAW
D FCAW GMAW
E FCAW FCAW
11
E FCAW FCAW
F FCAW MCAW
G MCAW GMAW
H MCAW FCAW
I MCAW MCAW
Root passes andfiller pass filled withsolid wire flux coredand metal cord wire.
Root passes filled withmetal cord wire and fillerpass with solid wire.
Root passes -solid wire.filler pass with metal cordor flux cored wire.
Fig.3
Proposed Objectives
Experiments are made to in single V (60) groove joint design for 10mm thickSA516 Gr70 carbon steel plate using Solid wire (ER70S6), flux cored wire (E71T-1C), and Metal Cored wire (E70C-6M) of 1.2 mm in diameter.
Establishment of Welding Parameters for welding SA516 Gr70 Carbon steel plateusing GMAW ,FCAW and MCAW process.
Destructive and Non-destructive testing and characterization of the welded joint asper applicable standards is carried out.
Comparison of Metallurgical & Mechanical properties of GMAW, FCAW &MCAW welded Joints.
Experiments are made to in single V (60) groove joint design for 10mm thickSA516 Gr70 carbon steel plate using Solid wire (ER70S6), flux cored wire (E71T-1C), and Metal Cored wire (E70C-6M) of 1.2 mm in diameter.
Establishment of Welding Parameters for welding SA516 Gr70 Carbon steel plateusing GMAW ,FCAW and MCAW process.
Destructive and Non-destructive testing and characterization of the welded joint asper applicable standards is carried out.
Comparison of Metallurgical & Mechanical properties of GMAW, FCAW &MCAW welded Joints.
13
Material Selection
SA516Gr70 carbon steel materials are widely used in heavy fabrication applicationin which cost saving factor and high strength are most important.
SA516 Grade 70 offers greater tensile and yield strength when compared to ASTMSA516 Grade 65 and can operate in even lower temperature service.
Table 1. Mechanical properties of consumables
Mechanical PropertiesSolid Wire
(ER70S-6)Flux Cored Wire
(E71T-1C)
Metal CoredWire
(E70C-6M)
Base metal
(SA516Gr70)
SA516Gr70 carbon steel materials are widely used in heavy fabrication applicationin which cost saving factor and high strength are most important.
SA516 Grade 70 offers greater tensile and yield strength when compared to ASTMSA516 Grade 65 and can operate in even lower temperature service.
Table 1. Mechanical properties of consumables
14
Solid Wire
(ER70S-6)Flux Cored Wire
(E71T-1C)
Metal CoredWire
(E70C-6M)
Yield Strength 427 MPa 605 MPa 448 MPa 446.9 MPa
Tensile Strength 529 MPa 579 MPa 549 MPa 590.60 MPa
Elongation 26% 31 % 31 % 24.8 %
CVN Impact Value
(Temp. C)35 J (30C)
80J (-20C) 103J(-30 C)
48J (-29C) 62J(-18C)
---
Shielding Gas --- 100% CO275% Ar-25%
CO2
---
Contents Solid Wire
(ER70S-6)Flux cored
wire
(E71T-1C)
Metal cored wire
(E70C-6M)Base metal
(SA516Gr70)
C 0.07 0.03 0.048 0.186
Si 0.86 0.56 0.582 0.322
Mn 1.44 1.29 1.375 1.112
0.014
Table 2. Chemical composition of the filler wire and SA516 Gr70 carbon steel material.
P 0.014 0.011 0.014 0.014
S 0.008 0.005 0.012 0.009
Cr 0.025 0.04 0.023 0.030
Ni 0.014 0.02 0.014 0.026
Mo 0.002 0.01 0.001 0.019
V 0.002 0.02 0.004 0.001
Nb N/A N/A 0.002 Nil
Cu 0.15 0.01 0.015 0.033
15
Experiment Procedure.
16
Power Source Equipment
Photograph of Experimental Setup
Ar/CO2Gas Mixer
Power Source Equipment
WeldingTorch
SPMHead
StandardGas
Cylinders
FumeExtractor
Data Monitoring System
Above setup available at PDPU( Research work carried out under sponsored project ofDepartment of Science and Technology (DST), New Delhi)
Fig.4
Experimental Condition
Base metal : SA516Grade70 Size : 30010010 mm Joint Design : V- groove (60 angle, Root Gap= 04 mm) Wire Type : 1.2 mm Solid (ER70S6), Flux cored (E71T-1C/M), MetalCored(E70C-6M) Welding Variable:
a) Normal Fe modeb) Welding Current -200 Ac) Welding Voltage 28 Vd) Travel Speed 200mm/mine) Nozzle to Plate Distance -15 mmf) Electrode Extension -8 to 10 mmg) Shielding Gas -90%Ar + 10% CO2
Base metal : SA516Grade70 Size : 30010010 mm Joint Design : V- groove (60 angle, Root Gap= 04 mm) Wire Type : 1.2 mm Solid (ER70S6), Flux cored (E71T-1C/M), MetalCored(E70C-6M) Welding Variable:
a) Normal Fe modeb) Welding Current -200 Ac) Welding Voltage 28 Vd) Travel Speed 200mm/mine) Nozzle to Plate Distance -15 mmf) Electrode Extension -8 to 10 mmg) Shielding Gas -90%Ar + 10% CO2
18
Fig.5 Joint Design
Fig.6.Photographs of welded plates
FMFSFF
19
Carbon steel plate SA516Gr70 welded using FF shows that both root pass and fillerpass filled with flux cored wire.
FS indicate Hybrid welds in which root pass filled with flux cored wire and fillerpass with solid wire.
FM indicate Hybrid shows that root pass filled with flux cored wire and filler passwith metal cored wired.
Table 3. Full plate Experimental Data
ID Current in Amp Voltage in VoltWeldingspeed inmm/min
Heat input KJ/mm
Set 1 (*) 2 (*) ActualAvg.(*) Set 1 (*) 2 (*)ActualAvg.(*) Set Cal. Cal.1 (*) Cal.2 (*)
ActualAvg.(*)
FF 200 273 282 277.5 28 27.9 28 27.95 200 1.68 2.28 2.36 2.32
FS 200 234 272 253.0 28 27.9 28.1 28.00 200 1.68 1.95 2.29 2.12
FM 200 228 271 249.5 28 27.9 28 27.95 200 1.68 1.90 2.27 2.09
20
1: First Trial 2: Second Trial .ctual (*): Values recorded by online data monitoring system (During Welding).
KJ/mm Where, V- Voltage,I- Current,S- Welding Speed-Welding Efficiency 0.9
Angular Distortion
Dial Indicator
21 Angular distortion measurement were carried as per the following procedure.
Fig.7 Schematic diagram of angular distortion measurements [30]
Weldingprocess
VerticalDisplacement Z in mm
HorizontalDisplacement
X in mm
Root runTemp.
Filler runTemp.
Avg. PeckTemperature
FF 4.66 100 2.68 420 394 407.0 Co
FS 4.98 100 2.66367 411 389Co
FM 3.94 100 1.72287 358 322.5 Co
Table 4. Angular Distortion and peck temperature Data
Contact typethermocouple
(K-Type- Nibase,chromel & alumel)
22Fig.(8) Calculated Angular Distortions
Contact typethermocouple
(K-Type- Nibase,chromel & alumel)
012345
FF FS FM
% Ang
u Dist
Consumables
Average pick temperature with flux coredwire is higher compare to other welds, becauseof high input recorded using flux cored wire, asshown in table 4That may be the reason for higher angulardistortion in FF and lowest in FM.
Macro preparation
The test specimen were cut from the welded plate after removing run on and runoff.
Each metallographic specimens were prepared by:- Mechanical grinding.- Polishing (120 and 320 grit silicon carbide),- Etching (solution of 35% concentrated HCL (60%) and 35%
concentrated HNO3 (40%) for 2-3 min to produce a bright surface.
The test specimen were cut from the welded plate after removing run on and runoff.
Each metallographic specimens were prepared by:- Mechanical grinding.- Polishing (120 and 320 grit silicon carbide),- Etching (solution of 35% concentrated HCL (60%) and 35%
concentrated HNO3 (40%) for 2-3 min to produce a bright surface.
23
FF FS FM
Fig.9
Table 5. Radiography Test Results of Full Plate.Sample Id Film Size (inch) Position Observation
FF 3 X 15 A/B Miner defect arereported andaccepted withinstandard
FS 3 X 15 A/B
FM 3 X 15 A/B
FFFF
24
FSFS
FMFM
25
Figure 10. . Plate less than 19mm Thickness Procedure Qualification(Pressurevessel and boiler code. ASME, Section IX) [25].
Destructive TestingTable 6. Tensile Test Specimens
Sample IdTensile test photos
RemarksFirst set
FF Specimen break from parent metal
26
FS Specimen break from parent metal
FM Specimen break from parent metal
Table- 7. Yield Strength and Tensile Strength for Welded joints.Sample Id Set of
ExperimentsYield
Strength(MPa)
Avg. YieldStrength(MPa)
TensileStrength(MPa)
Avg. TensileStrength(MPa)
Observation
FF 1387
359611
565 Broken fromparent
330 519
382 517
27
FS 2
382
385517
568 Broken fromparent
388 619
FM 3375
379562
559 Broken fromparent
382 555
Average yield strength and tensile strength values are higher for FS hybrid weld.
Fig.11 Effect of wires on mechanical yieldstrength
Fig.12 Effect of wires on mechanical Tensilestrength.
300320340360380400420
FF FS FM
YS in
MPa
Consumables
500520540560580600
FF FS FM
TS in
MPa
Consumables
28
Fig.11 Effect of wires on mechanical yieldstrength
Fig.12 Effect of wires on mechanical Tensilestrength.
This may be due to the externally fine microstructure (ferrite, Widmanstttenferrite, and acicular ferrite) developed.Additionally, it is future conform through the weld metal chemical analysis as shown intable 9.it was found that C-Mn-S for FS weld metal is higher compared to filler metal.The variation in properties across the weld can be attributed
Table-8 %Elongation Area for welded Joints
SampleId
Set ofspecimen
%Elongation
Avg. %Elongation
FF1 25 232 21
FS1 08
152 22
FM1 20
232 26
29
05
1015202530
FF FS FM
% Elon
gation
ConsumablesFig.(13) Effect of wires on % Elongation
Result:- Percent elongation is higher forflux cored weld (FF) as compare to hybridwelds
Table-9 Joint efficiency of welded joint.
Sample Id Weld Joint Strengthin MPa
Joint Efficiency in %
FF 565.05 96
FS 568.00 96
FM 558.20 95
Result:- Joint efficiency of weldedjoint is defined as a ratio of strengthof weld metal to the strength ofparent metal.Strength of parent metal is590MPa.
Joint efficiency is very by 2%only.
100
30Fig. (14) Different wires on joint efficiency
Result:- Joint efficiency of weldedjoint is defined as a ratio of strengthof weld metal to the strength ofparent metal.Strength of parent metal is590MPa.
Joint efficiency is very by 2%only.
80859095
100
FF FS FM
Joint
Efficie
ncy
Consumables
Table -8 Bend test photos
ID
Bend Test
RemarksFace bend Root BendSet. 1 Set. 2
FFPass
31
FSPass
FM Pass
Table -9 Impact Test Results.
Weldingprocess
Charpy impact test at -49 C. energy absorbed in Joule
set of specimen Avg.Weld
set of specimen Avg.HAZI II II I I III
FF 46 44 38 43 32 38 36 35
FS 44 50 52 49 26 22 22 24
FM 20 24 18 21 24 28 22 25
60
32
(G) Impact test results Weld and HAZ
Fig.(15) Impact test results Weld and HAZ
Result:- Highest Impact value reported forFS welds and lowest for FM welds. Whilein HAZ highest impact values reported forFF..
1015202530354045505560
FF FS FM
Impa
ct Tes
t in J
Consumables
WELD
HAZ
Vickers Hardness Measurement Specimens prepared for macrostructure observation were utilized for VHN measurement.
Specification of the machine as follow. Vickers hardness was measured as per standard ASTM,A 370-07 in both in both
transverse(weld metal, HAZ, and parent metal) direction and vertical(root to filler pass)direction.
Each indentation was separated by 1mm at 10 Kg for macro hardness and 300grms formicro hardness.
Equipment : ESEWAY-4000.Modal-4302 Load : 10 Kg & 300grm Dwell Time : 15 Sec. Objective : 20 X
Specimens prepared for macrostructure observation were utilized for VHN measurement.Specification of the machine as follow.
Vickers hardness was measured as per standard ASTM,A 370-07 in both in bothtransverse(weld metal, HAZ, and parent metal) direction and vertical(root to filler pass)direction.
Each indentation was separated by 1mm at 10 Kg for macro hardness and 300grms formicro hardness.
Equipment : ESEWAY-4000.Modal-4302 Load : 10 Kg & 300grm Dwell Time : 15 Sec. Objective : 20 X
33Fig- 16: Vicker hardness tester - (ESEWAY-4000.Modal-4302) at PDPU
Fig17. VHN at different (transverse direction) zones at (HV10)
100115130145160175190205220235250265280
-15
-14
-13
-12
-11
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
HV
10
Dist. from Center of weld to both side
FF
FS
FM
34
Fig 18. VHN at different (vertical direction) zones at (HV10)
150165180195210225240255270285300
-5 -4 -3 -2 -1 0 1 2 3 4 5
HV
10
Dist. from Center of weld to both side
FF
FS
FM
Root side Filler side
Fig 19. VHN at different (transverse direction) zones at (HV0.3)
Fig 20. VHN at different (Vertical direction) zones at (HV0.3)
100115130145160175190205220235250265280295310325340355370385400
-15
-14
-13
-12
-11
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
HV
0.3
Dist. from Center of weld to both side
FF
FS
FM
35
Fig 20. VHN at different (Vertical direction) zones at (HV0.3)
120140160180200220240260280300320340360380400
-5 -4 -3 -2 -1 0 1 2 3 4 5
HV
0.3
Dist. from Center of weld to both side
FF
FSFM
Root side Filler side
Contentin %
FF FS FM
Filler
WireWeldedSample Filler Wire
WeldedSample Filler Wire
WeldedSample
Carbon 0.07 0.112 0.03 0.092 0.048 0.108
Manganese 1.44 1.510 1.29 1.415 1.375 1.309
TABLE 10. Chemical analysis of weld metal
36
Silicon 0.86 0.618 0.56 0.674 0.582 0.391
= increased and = decreased compared with filler wire %.
From above table , C-Mn-Si for FS welds metal is higher compared to filler metal.
In second cases, C-Mn % for FF welds metal is higher compared to filler metal, while Si islow record. C for FM weld higher while Mn-Si is lower compared to filler metal.
From table 10, in some cause % for Manganese and % of silicon in weld metal isreduced as compared to filler wire because of all this element react with oxygenstrongly during welding.
The loss of manganese and silicon may be caused by oxidation reactions in theweld pool: [20]
Carbon, decreases. the ductility, formability, weldability and increases the strengthand hardenability.
Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. Thisalso makes the steel more stable in the quench
Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other
alloys can help increase the toughness and hardness penetration of steel.
From table 10, in some cause % for Manganese and % of silicon in weld metal isreduced as compared to filler wire because of all this element react with oxygenstrongly during welding.
The loss of manganese and silicon may be caused by oxidation reactions in theweld pool: [20]
Carbon, decreases. the ductility, formability, weldability and increases the strengthand hardenability.
Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. Thisalso makes the steel more stable in the quench
Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other
alloys can help increase the toughness and hardness penetration of steel.
37
(a) Microstructure ofFCAWParent
(b) Microstructure of PM &HAZleft (interface)
(c) Microstructure ofTop run
Microstructure of the FF Samples at (200X)
Normalweld
38
(d) Microstructure ofMiddle run
(f) Microstructure of Root run
Hybridweld
(g) Microstructure ofPM &HAZ Right
(interface)
(a) Microstructure ofParent
(b) Microstructure of PM &HAZleft (interface)
(c) Microstructure ofTop run
Hybridweld
Microstructure of the FS Samples at (200X)
(d) Microstructure ofMiddle run
(e) Microstructure of Root run
Hybridweld
(f) Microstructure of PM &HAZ Right(interface)
(a) Microstructure ofParent (b) Microstructure of PM &HAZ
left(interface)
(c) Microstructure ofTop run
Hybridweld
Microstructure of the FM Samples at (200X)
(d) Microstructure ofMiddle run
(g) Microstructure ofRoot run
(h) Microstructure ofPM &HAZ
Right (interface)(f) Microstructure ofMiddle run (50 X)
The properties of the steel depends upon the microstructure. Decreasing the size of thegrains and decreasing the amount of pearlite improve the strength, ductility andtoughness of the steelMicrostructure investigation reflects the extremely fine grain structure of weld and aswell HAZ of FS weld.It has two major constituents, which are ferrite and pearlite.Its major components include allotriomorphic ferrite, Widmansttten (called side plateferrite) ferrite, and acicular ferrite.The dark regions are the microstructure is the pearlite. it is made up from a finemixture of ferrite and iron carbide.The light coloured region is the ferrite. boundary ferrite is called allotriomorphicferrite.
41
The properties of the steel depends upon the microstructure. Decreasing the size of thegrains and decreasing the amount of pearlite improve the strength, ductility andtoughness of the steelMicrostructure investigation reflects the extremely fine grain structure of weld and aswell HAZ of FS weld.It has two major constituents, which are ferrite and pearlite.Its major components include allotriomorphic ferrite, Widmansttten (called side plateferrite) ferrite, and acicular ferrite.The dark regions are the microstructure is the pearlite. it is made up from a finemixture of ferrite and iron carbide.The light coloured region is the ferrite. boundary ferrite is called allotriomorphicferrite.
42
Figure13. Fracture morphology (SEM image) of tensile specimen fractured at room temperature, (a) FF sample,(b) FS sample. (C) FM sample. The inclusion is indicated by the arrow. The EDAX spectra of the inclusions areshown in Fig
FF sample FS sample
In all sample, the results of the EDXanalyses indicated that the inclusionscontained manganese, iron, carbon andnickel, silicon as shown in Fig .
43
Small spots within the ferrite grains. These inclusions are silicon oxides and manganeseoxides, and sulphides etc.The difference in composition of the inclusions is due to the different sources of theinclusions.In MAG, the Impurities mainly arose from the shielding gas. In FCAW, the impuritiesmainly arose from the ux and shielding gas. [18]
FM sample
Image Analyser ERDA, Baroda
Model: Olympus
Scanning ElectronMicroscope - PDPU
Model : ZEISS ULTRA 55 44
CONCLUSIONS The angular distortion is higher with flux cored wire compare to hybrid weld. Pick temperature reported with flux cored wire is higher compare to hybrid weld
which shown that high hear input with welding with flux cored wire. Yield strength and tensile strength values are higher for with FS hybrid weld. Percent elongation is higher for flux cored wire as compare to hybrid welds During tensile test all specimens failed from parent material; means welded joints
are stronger then parent metal. Samples welded with different consumables shows good integrity of welded
joints during bend test. Excellent impact toughness of the weld metal reported for the FS hybrid welds
compared to other cases. Higher macro and micro hardness value reported for flux cored welds compare to
others hybrid welds. Weld metal microstructure confirm the presence of allotriomorphic ferrite,
Widmansttten ferrite, and acicular ferrite in the weld metal.
The angular distortion is higher with flux cored wire compare to hybrid weld. Pick temperature reported with flux cored wire is higher compare to hybrid weld
which shown that high hear input with welding with flux cored wire. Yield strength and tensile strength values are higher for with FS hybrid weld. Percent elongation is higher for flux cored wire as compare to hybrid welds During tensile test all specimens failed from parent material; means welded joints
are stronger then parent metal. Samples welded with different consumables shows good integrity of welded
joints during bend test. Excellent impact toughness of the weld metal reported for the FS hybrid welds
compared to other cases. Higher macro and micro hardness value reported for flux cored welds compare to
others hybrid welds. Weld metal microstructure confirm the presence of allotriomorphic ferrite,
Widmansttten ferrite, and acicular ferrite in the weld metal.
45
While comparing the mechanical properties of the FF welds with FS and FM. It wasfound that FS weld is better compared to others in terms of YS, TS JE and weldimpact. This may be due to the externally fine microstructure (ferrite,Widmansttten ferrite, and acicular ferrite) developed.
Additionally, it is future conform through the weld metal chemical analysis asshown in table 9.it was found that C-Mn-S for FS weld metal is higher compared tofiller metal.
46
Paper submitted
1.International Journal of Pressure Vessels and Piping (ELSEVIER).Impact Factor: 1.532,Date-26/12/2014, DC ON 12/12/2014
Title: The effect of welding consumables on the Mechanical and Metallurgicalproperties of carbon Steel Material. Current Status: Paper under review.
2. Journal of Pressure Vessel Technology ,ASMEsubmitted on Date-13/04/2015
Title: The effect of Hybrid Weldments on the Mechanical and Metallurgical.Properties of carbon Steel Material.
Current Status: comments received from reviewer.
47
Paper submitted
1.International Journal of Pressure Vessels and Piping (ELSEVIER).Impact Factor: 1.532,Date-26/12/2014, DC ON 12/12/2014
Title: The effect of welding consumables on the Mechanical and Metallurgicalproperties of carbon Steel Material. Current Status: Paper under review.
2. Journal of Pressure Vessel Technology ,ASMEsubmitted on Date-13/04/2015
Title: The effect of Hybrid Weldments on the Mechanical and Metallurgical.Properties of carbon Steel Material.
Current Status: comments received from reviewer.
Originality AcceptableSignificance AcceptableScientific relevance AcceptableCompleteness AcceptableAcknowledgment of the Work of others by References AcceptableOrganization MarginalClarity of Writing MarginalClarity of Tables, Graphs, and Illustrations MarginalIn your opinion, is the technical treatment plausible and free of technicalerrors?
Yes
Reviewer 1:
48
In your opinion, is the technical treatment plausible and free of technicalerrors?
Yes
Have you checked the equations? NoAre you aware of prior publication or presentation of this work? NoIs the work free of commercialism? YesIs the title brief and descriptive? YesDoes the abstract clearly indicate objective, scope, and results? Yes
This paper is Not Acceptable (Revision required; resubmit as Tech. Brief) . The qualityof the paper is Good.
Recommendation
The work appears to be original and meaningful.
Originality Acceptable
Significance Acceptable
Scientific relevance Acceptable
Completeness Marginal
Acknowledgment of the Work of others by References Marginal
Organization Acceptable
Clarity of Writing Poor
Clarity of Tables, Graphs, and Illustrations Marginal
In your opinion, is the technical treatment plausible and free of technical errors? Yes
Reviewer 2:
49
In your opinion, is the technical treatment plausible and free of technical errors? Yes
Have you checked the equations? Yes
Are you aware of prior publication or presentation of this work? No
Is the work free of commercialism? Yes
Is the title brief and descriptive? Yes
Does the abstract clearly indicate objective, scope, and results? No
This paper is Not Acceptable (Revision and resubmitted required) . The quality of thepaper is Average.
Recommendation
Internal Assessment seminar topics
(1) Non- Destructive testing of welds- all.(Delivered on 05/09/2013)(2) Heat Flow during welding. (Delivered on 10/10/2013)(3) M.Tech presentation. (Delivered on 27/01/ 2014)(4) Destructive testing of welds- all. (Delivered 15th May 2014)(5) Welding symbol (Delivered 29th Des 2014)(6) Welding Metallurgy (will be deliver before 11nd June2015)
Internal Assessment seminar topics
(1) Non- Destructive testing of welds- all.(Delivered on 05/09/2013)(2) Heat Flow during welding. (Delivered on 10/10/2013)(3) M.Tech presentation. (Delivered on 27/01/ 2014)(4) Destructive testing of welds- all. (Delivered 15th May 2014)(5) Welding symbol (Delivered 29th Des 2014)(6) Welding Metallurgy (will be deliver before 11nd June2015)
References
1. American Welding Society - Welding Hand book, Welding Processes, Eighth Edition - Vol.II, pp 110, pp 157-190.2. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 582-583.3. www.esabna.com, "Advantages and Disadvantages of metal cored wire".4. Nasir Ahmed, "New development in advance welding", Pub. Wood Head publishing limited Cambridge, England; pp 23.5. Stanley E. Ferree, Michael S, Sierdzinski, "Stainless steel metal cored wires for welding automotive exhaust systems" ESAB
Welding and Cutting Products, Hanover (PA) USA. Svetsaren nr i , 2000, pp 15-18.6. Kevin A. Lyttle, Praxair, Inc Senior Development Associate; "Metal Cored Wire: Where Do They Fit In Your Future?" Reprinted
from Welding Journal, Oct. 1996, pp 35-38.7. www.esabmanualcom, "Flux Core arc Welding, ESAB".8. David Widgery; Tubular wire welding, Jaico Publishing House.9. Washington alloy co. www.weldingwire.com.10. Avesatar welding www.avestarwelding.com.11. BOC, IPRM 2006: Section 4: Welding processes.12. BOC, AU: IPRM 2007: Section 8: Consumables.13. M. Suban, J. Tusek, "Dependance of melting rate in MIG/MAG welding on the type of shielding gas used", Journal of Materials
Processing Technology 119 (2001), pp 185-192.14. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 163-174.15. Tom Myers,"Choosing a shielding Gas for FCAW", A senior application engineer, The Lincoln Electric Co; Cleveland, Ohio.16. John Norrish, -Advanced welding processes technologies and process control", Pub. Wood.17. Head publishing limited Cambridge", England pp 108.18. V. V. Vaidya, "Theory and practice of shielding gas mixtures for semiautomatic welds", Director, welding Technology and Business
Development, Air Liquide Canada Inc., Canada.19. M Menzel, "The influence of individual components of an industrial gas mixture on the welding process and the properties of
welded joints". Linde Gas Poland; Welding International 2003 17 (4) 262-264.20. .S. Mukhopadhyay and T.K.Pal.; "Effect of shielding gas mixture on gas metal arc welding of HSLA steel using solid and flux-cored
wires". Welding Technology Centre, Metallurgical Engineering Department, Jadavpur University, Kolkata.21. AMOS DAVIS, business development manager, "Optimizing Metal Cored Performance" Hobart Brothers Company, Feb 1, 2009;
12:00 PM.22. W. F. Garth Stapon, "Using Flux cored and Metal Cored Wire". Praxair. Inc. Marketing Manager Metal Fabrication; Reprinted from
Practical Welding Today Jan/Feb 2000.23. V. Vel Murugan and V. Gunaraj, "Effect of process parameters on Angular Distortion of gas metal arc welded structural steel plates",
Welding Journal, November 2005.51
References
1. American Welding Society - Welding Hand book, Welding Processes, Eighth Edition - Vol.II, pp 110, pp 157-190.2. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 582-583.3. www.esabna.com, "Advantages and Disadvantages of metal cored wire".4. Nasir Ahmed, "New development in advance welding", Pub. Wood Head publishing limited Cambridge, England; pp 23.5. Stanley E. Ferree, Michael S, Sierdzinski, "Stainless steel metal cored wires for welding automotive exhaust systems" ESAB
Welding and Cutting Products, Hanover (PA) USA. Svetsaren nr i , 2000, pp 15-18.6. Kevin A. Lyttle, Praxair, Inc Senior Development Associate; "Metal Cored Wire: Where Do They Fit In Your Future?" Reprinted
from Welding Journal, Oct. 1996, pp 35-38.7. www.esabmanualcom, "Flux Core arc Welding, ESAB".8. David Widgery; Tubular wire welding, Jaico Publishing House.9. Washington alloy co. www.weldingwire.com.10. Avesatar welding www.avestarwelding.com.11. BOC, IPRM 2006: Section 4: Welding processes.12. BOC, AU: IPRM 2007: Section 8: Consumables.13. M. Suban, J. Tusek, "Dependance of melting rate in MIG/MAG welding on the type of shielding gas used", Journal of Materials
Processing Technology 119 (2001), pp 185-192.14. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 163-174.15. Tom Myers,"Choosing a shielding Gas for FCAW", A senior application engineer, The Lincoln Electric Co; Cleveland, Ohio.16. John Norrish, -Advanced welding processes technologies and process control", Pub. Wood.17. Head publishing limited Cambridge", England pp 108.18. V. V. Vaidya, "Theory and practice of shielding gas mixtures for semiautomatic welds", Director, welding Technology and Business
Development, Air Liquide Canada Inc., Canada.19. M Menzel, "The influence of individual components of an industrial gas mixture on the welding process and the properties of
welded joints". Linde Gas Poland; Welding International 2003 17 (4) 262-264.20. .S. Mukhopadhyay and T.K.Pal.; "Effect of shielding gas mixture on gas metal arc welding of HSLA steel using solid and flux-cored
wires". Welding Technology Centre, Metallurgical Engineering Department, Jadavpur University, Kolkata.21. AMOS DAVIS, business development manager, "Optimizing Metal Cored Performance" Hobart Brothers Company, Feb 1, 2009;
12:00 PM.22. W. F. Garth Stapon, "Using Flux cored and Metal Cored Wire". Praxair. Inc. Marketing Manager Metal Fabrication; Reprinted from
Practical Welding Today Jan/Feb 2000.23. V. Vel Murugan and V. Gunaraj, "Effect of process parameters on Angular Distortion of gas metal arc welded structural steel plates",
Welding Journal, November 2005.
26. 26. ASTM-A ferrous metals 2006 SA 516 Gr-70.27. Gas metal are welding of carbon steel (PRAXAIR).28. Mario Teske and Fabio Martins, The influence of the shielding gas composition on GMA welding of ASTM A 516 steel. Federal Technological
University of Parana, Campus Curitiba, Brazil.29. Cicero Murta Diniz Starling, Paulo Jose Modenesi, and Tadeu Messias Donizete Borba, Comparison of operational performance and bead characteristics
when welding with different tubular wires, Welding international, Vol. 24, No 8, August 2010, 579-592.30. R. M. Mirza and R. Gee;Effects of shielding gases on weld diffusible hydrogen contents using cored wire; Science and Technology of welding and
joining, 1999, vol. 4, no.2.31. Ravi Menon,; Recent advances in cored wires for hardfacing. Vice President, Technology, Stoody Co; a Thermadyne company, Bowling Green.32. N. M. Ramini DE Rissone; H. G. Svoboda; E. S. Surian, and L. A. DE Vedia; Influence of procedure variables on C-Mn-Ni-Mo metal cored wire ferrites
all weld metal. Supplement to the welding journal, September 2005.33. Lucilene de Oliveira Rodrigues, Anderson Paulo de Paiva and Sebastiao Carlos de Costa; Optimization of the FCAW process by bead geometry
analysis, Welding International, Vol.23, No.4, Aprial 2009, 261-269.34. D. D. Harwig; D. P. Longeneker and J. H. Cruz; Effect of welding parameters and electrode atmospheric exposure on the diffusible hydrogen content of
shielding flux cored arc welds, AWS welding Journal, September 1999.35. K. S. Bang; D. H. Jung; C. Park and W. S. Chang; Effect of welding parameters on tensile strength of weld metal in flux cored arc welding, Science and
Technology of welding and joining, 2008, vol. 13, no.6, 509.36. T. Kannan & J. Yoganandh, Effect of process parameters on clad bead geometry and its shape relationships of stainless steel claddings deposited by
GMAW, Int Adv Manuf Technology (2010), 30: 1083-1095.37. ESAB; Welding Handbook; Eighth edition.38. Her-Yueh Huang; Effects of activating flux on the welded joint characteristics in gas metal arc welding. Department of Materials Science and
Engineering, National Formosa University, Yunlin 632, Taiwan.39. The ABC's of Arc Welding; KOBELCO WELDING TODAY.40. www.wikipedia.com Equivalent Carbon Content.41. H. K. D. H. Bhadeshia and Sir Robert Honeycombe; Steels: Microstructure and Properties: Third edition; Published by Elsevier Ltd. 2006.42. Flux Cored Arc Welding Equipment, Setup, and Operation Chapter no 3.43. Welding Kita-Shinagawa, Shinagawa-Ku Essential Factors in Gas Metal Arc 2011 by Kobe Steel, Ltd Fourth Edition , Tokyo, 141-8688 Japan.44. Shielding Gases Selection Manual (Praxair).45. British patent 8580854, Mar 29, 1957.46. Welding Design and Fabrication, a Penton Media, Inc. publication. May 1999 6/8/1999, New AWS Specs-Electrode Selection.47. Nick Kapustka Arc Welding Capabilities at EWI, November 29, 2012 .ewi.org 614.688.5000.48. Jeff Nadzam, Senior Application Engineer Lincon electrical, Gas Metal Arc Welding , Carbon, Low Alloy, and Stainless Steels and Aluminum, MIG
C4.200 9/06.49. Syarul Asraf Mohamat,, Izatul Aini Ibrahim, , Amalina Amir , Abdul Ghalib The Effect of Flux Core Arc Welding (FCAW) processes on different
parameters SciVerse ScienceDirect , International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012) Procedia Engineering 41 ( 2012 )1497 1501.
50. Vishvesh J Badheka , Hardik Vyas Comparisons of GMA, FCA and MCA weldments of SA516 Gr70 Steel Material.51. Ramy Gadallah , Raouf Fahmy ,Tarek Khalifa, Alber Sadek Influence of Shielding Gas Composition on the Properties of Flux-Cored Arc Welds of
Plain Carbon Steel.International Journal of Engineering and Technology Innovation, vol. 2, no. 1, 2012, pp. 01-12.
52. ASME. Pressure vessel and boiler code. New York (NY): ASME, Section IX.53. K.E. Dorschu. Factors affecting weld metal properties in carbon and low alloy pressure vessel steels. sponsored by the pressure vessel research committee
of the welding research council, WRC bulletin 231.
26. 26. ASTM-A ferrous metals 2006 SA 516 Gr-70.27. Gas metal are welding of carbon steel (PRAXAIR).28. Mario Teske and Fabio Martins, The influence of the shielding gas composition on GMA welding of ASTM A 516 steel. Federal Technological
University of Parana, Campus Curitiba, Brazil.29. Cicero Murta Diniz Starling, Paulo Jose Modenesi, and Tadeu Messias Donizete Borba, Comparison of operational performance and bead characteristics
when welding with different tubular wires, Welding international, Vol. 24, No 8, August 2010, 579-592.30. R. M. Mirza and R. Gee;Effects of shielding gases on weld diffusible hydrogen contents using cored wire; Science and Technology of welding and
joining, 1999, vol. 4, no.2.31. Ravi Menon,; Recent advances in cored wires for hardfacing. Vice President, Technology, Stoody Co; a Thermadyne company, Bowling Green.32. N. M. Ramini DE Rissone; H. G. Svoboda; E. S. Surian, and L. A. DE Vedia; Influence of procedure variables on C-Mn-Ni-Mo metal cored wire ferrites
all weld metal. Supplement to the welding journal, September 2005.33. Lucilene de Oliveira Rodrigues, Anderson Paulo de Paiva and Sebastiao Carlos de Costa; Optimization of the FCAW process by bead geometry
analysis, Welding International, Vol.23, No.4, Aprial 2009, 261-269.34. D. D. Harwig; D. P. Longeneker and J. H. Cruz; Effect of welding parameters and electrode atmospheric exposure on the diffusible hydrogen content of
shielding flux cored arc welds, AWS welding Journal, September 1999.35. K. S. Bang; D. H. Jung; C. Park and W. S. Chang; Effect of welding parameters on tensile strength of weld metal in flux cored arc welding, Science and
Technology of welding and joining, 2008, vol. 13, no.6, 509.36. T. Kannan & J. Yoganandh, Effect of process parameters on clad bead geometry and its shape relationships of stainless steel claddings deposited by
GMAW, Int Adv Manuf Technology (2010), 30: 1083-1095.37. ESAB; Welding Handbook; Eighth edition.38. Her-Yueh Huang; Effects of activating flux on the welded joint characteristics in gas metal arc welding. Department of Materials Science and
Engineering, National Formosa University, Yunlin 632, Taiwan.39. The ABC's of Arc Welding; KOBELCO WELDING TODAY.40. www.wikipedia.com Equivalent Carbon Content.41. H. K. D. H. Bhadeshia and Sir Robert Honeycombe; Steels: Microstructure and Properties: Third edition; Published by Elsevier Ltd. 2006.42. Flux Cored Arc Welding Equipment, Setup, and Operation Chapter no 3.43. Welding Kita-Shinagawa, Shinagawa-Ku Essential Factors in Gas Metal Arc 2011 by Kobe Steel, Ltd Fourth Edition , Tokyo, 141-8688 Japan.44. Shielding Gases Selection Manual (Praxair).45. British patent 8580854, Mar 29, 1957.46. Welding Design and Fabrication, a Penton Media, Inc. publication. May 1999 6/8/1999, New AWS Specs-Electrode Selection.47. Nick Kapustka Arc Welding Capabilities at EWI, November 29, 2012 .ewi.org 614.688.5000.48. Jeff Nadzam, Senior Application Engineer Lincon electrical, Gas Metal Arc Welding , Carbon, Low Alloy, and Stainless Steels and Aluminum, MIG
C4.200 9/06.49. Syarul Asraf Mohamat,, Izatul Aini Ibrahim, , Amalina Amir , Abdul Ghalib The Effect of Flux Core Arc Welding (FCAW) processes on different
parameters SciVerse ScienceDirect , International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012) Procedia Engineering 41 ( 2012 )1497 1501.
50. Vishvesh J Badheka , Hardik Vyas Comparisons of GMA, FCA and MCA weldments of SA516 Gr70 Steel Material.51. Ramy Gadallah , Raouf Fahmy ,Tarek Khalifa, Alber Sadek Influence of Shielding Gas Composition on the Properties of Flux-Cored Arc Welds of
Plain Carbon Steel.International Journal of Engineering and Technology Innovation, vol. 2, no. 1, 2012, pp. 01-12.
52. ASME. Pressure vessel and boiler code. New York (NY): ASME, Section IX.53. K.E. Dorschu. Factors affecting weld metal properties in carbon and low alloy pressure vessel steels. sponsored by the pressure vessel research committee
of the welding research council, WRC bulletin 231.52
53
EFFECT OF ALLOYING ELEMENT IN STEEL .[53]Carbon (C): Carbon is an element whose presence is imperative in all steel. Indeed, carbon is theprinciple hardening element of steel. That is, this alloying element determines the level of hardness or strength that can
be attained by quenching. Furthermore, carbon is essential for the formation ofcementite (as well as other carbides) and of pearlite, spheridite, bainite, and iron-carbon martensite, with martensite being the hardest of the microstructures.
Carbon is also responsible for increase in tensile strength, hardness, resistance towear and abrasion.
However, when present in high quantities it affects the ductility, the toughness andthe machinability of steel.
They are described as follows:Low Carbon: Under 0.4 percent Medium Carbon: 0.4 - 0.6 percent High Carbon: 0.7 - 1.5
percent Carbon is the single most important alloying element in steel.
EFFECT OF ALLOYING ELEMENT IN STEEL .[53]Carbon (C): Carbon is an element whose presence is imperative in all steel. Indeed, carbon is theprinciple hardening element of steel. That is, this alloying element determines the level of hardness or strength that can
be attained by quenching. Furthermore, carbon is essential for the formation ofcementite (as well as other carbides) and of pearlite, spheridite, bainite, and iron-carbon martensite, with martensite being the hardest of the microstructures.
Carbon is also responsible for increase in tensile strength, hardness, resistance towear and abrasion.
However, when present in high quantities it affects the ductility, the toughness andthe machinability of steel.
They are described as follows:Low Carbon: Under 0.4 percent Medium Carbon: 0.4 - 0.6 percent High Carbon: 0.7 - 1.5
percent Carbon is the single most important alloying element in steel.
54
Manganese (Mn):Increases the strength, shock resistance, toughness, hardenability, weldebility, hotformability, no change in ductility. In addition Mn is a strong austenite former by reducing the eutectoid temperaturebelow to room temperature.Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. This alsomakes the steel more stable in the quench.
Sulfur (S):The excess sulfur reduces the ability for hot (900C) deformation of steel forming thebrittle FeS phase at the grain boundaries (hot brittleness).
The solubility of S is higher than C therefore it restricts the formation of pearlite in thezones with higher S contents, leading a banded structure of pearlite and ferrite.(Macroscopy experiment: flow lines). This causes severe anisotropy in the mechanicalprop of steel therefore S content is limited 0.035%.
However, 0.3% S may be added to free cutting steels to increase the chip formationthus the machinability
55
Manganese (Mn):Increases the strength, shock resistance, toughness, hardenability, weldebility, hotformability, no change in ductility. In addition Mn is a strong austenite former by reducing the eutectoid temperaturebelow to room temperature.Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. This alsomakes the steel more stable in the quench.
Sulfur (S):The excess sulfur reduces the ability for hot (900C) deformation of steel forming thebrittle FeS phase at the grain boundaries (hot brittleness).
The solubility of S is higher than C therefore it restricts the formation of pearlite in thezones with higher S contents, leading a banded structure of pearlite and ferrite.(Macroscopy experiment: flow lines). This causes severe anisotropy in the mechanicalprop of steel therefore S content is limited 0.035%.
However, 0.3% S may be added to free cutting steels to increase the chip formationthus the machinability
Silicone (Si): Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other
alloys can help increase the toughness and hardness penetration of steel. It increases strength, decreases the weldability, magnetic losses, oxide formation
affinity, no change in ductility. In addition Si has higher affinity to O than carbon therefore used as deoxizing agent
(semi-killed steels). It is also austenite former agent leading the nucleation of austenite grain in many
size yielding finer grain size.Copper (Cu):
Copper The addition of copper in amounts of 0.2 to 0.5 percent primarily improvessteels resistance to atmospheric corrosion. It should be noted that with respect toknife steels, copper has a detrimental effect to surface quality and to hot-workingbehavior due to migration into the grain boundaries of the steel.
Copper (Cu): restricted to max. 0.35%. Up to 0.2 % provides some resistanceagainst to atmospheric corrosion. Not desired in spring steels.
Silicone (Si): Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other
alloys can help increase the toughness and hardness penetration of steel. It increases strength, decreases the weldability, magnetic losses, oxide formation
affinity, no change in ductility. In addition Si has higher affinity to O than carbon therefore used as deoxizing agent
(semi-killed steels). It is also austenite former agent leading the nucleation of austenite grain in many
size yielding finer grain size.Copper (Cu):
Copper The addition of copper in amounts of 0.2 to 0.5 percent primarily improvessteels resistance to atmospheric corrosion. It should be noted that with respect toknife steels, copper has a detrimental effect to surface quality and to hot-workingbehavior due to migration into the grain boundaries of the steel.
Copper (Cu): restricted to max. 0.35%. Up to 0.2 % provides some resistanceagainst to atmospheric corrosion. Not desired in spring steels.
56
Chromium (Cr): As the Cr content increases, strength, hardenability, corrosion resistance, high
temperature strength, decreases the oxide formation tendency. (forms a verycoherent oxide layer on the surface preventing further oxidation-- in stainlesssteels).
It is also strong carbide former as an essential factor behaving as a strong secondphase particle, therefore, obstructs the dislocation motion particularly at elevatedtemperatures. Also nitride former and used in nitriding steels.
Chromium As with manganese, chromium has a tendency to increase hardnesspenetration. This element has many interesting effects on steel.
Phosphorus It increases strength and hardness and decreases ductility and notch impact
toughness of steel. The adverse effects on ductility and toughness are greater in quenched and
tempered higher-carbon steels.
Nickel Nickel is a ferrite strengthener. Nickel does not form carbides in steel. It remains
in solution in ferrite, strengthening and toughening the ferrite phase. Nickelincreases the harden ability and impact strength of steels.
Chromium (Cr): As the Cr content increases, strength, hardenability, corrosion resistance, high
temperature strength, decreases the oxide formation tendency. (forms a verycoherent oxide layer on the surface preventing further oxidation-- in stainlesssteels).
It is also strong carbide former as an essential factor behaving as a strong secondphase particle, therefore, obstructs the dislocation motion particularly at elevatedtemperatures. Also nitride former and used in nitriding steels.
Chromium As with manganese, chromium has a tendency to increase hardnesspenetration. This element has many interesting effects on steel.
Phosphorus It increases strength and hardness and decreases ductility and notch impact
toughness of steel. The adverse effects on ductility and toughness are greater in quenched and
tempered higher-carbon steels.
Nickel Nickel is a ferrite strengthener. Nickel does not form carbides in steel. It remains
in solution in ferrite, strengthening and toughening the ferrite phase. Nickelincreases the harden ability and impact strength of steels.
57
The Iron-Iron Carbide Diagram A map of the temperature at which different phase changes occur on very
slow heating and cooling in relation to Carbon, is called Iron- CarbonDiagram.
Iron- Carbon diagram shows the type of alloys formed under very slow cooling, proper heat-treatment temperature and how the properties of steels and cast irons can be radically changed
by heat-treatment. Plain carbon steels are generally defined as being those alloys of iron
and carbon which contain up to 2.0% carbon The pure metal Iron, at temperatures below 910C, has a
body-centred cubic structure, and if we heat it to above thistemperature the structure will change to one which is face centredcubic.
A map of the temperature at which different phase changes occur on veryslow heating and cooling in relation to Carbon, is called Iron- CarbonDiagram.
Iron- Carbon diagram shows the type of alloys formed under very slow cooling, proper heat-treatment temperature and how the properties of steels and cast irons can be radically changed
by heat-treatment. Plain carbon steels are generally defined as being those alloys of iron
and carbon which contain up to 2.0% carbon The pure metal Iron, at temperatures below 910C, has a
body-centred cubic structure, and if we heat it to above thistemperature the structure will change to one which is face centredcubic.
IRON IRON-CARBON DIAGRAM
Austenite
Pearlite andCementine
Eutecticeutectoid
Ferrite
Steel Cast iron
Pearlite
Pearlite andCarbide
The Iron-Iron Carbide Diagram
The diagram shows three horizontal lines which indicate isothermal reactions (oncooling / heating):
First horizontal line is at 1490C, where peritectic reaction takes place:Liquid + austenite
Second horizontal line is at 1130C, where eutectic reaction takes place:liquid austenite + cementite
Third horizontal line is at 723C, where eutectoid reaction takes place:austenite pearlite (mixture of ferrite & cementite).
The diagram shows three horizontal lines which indicate isothermal reactions (oncooling / heating):
First horizontal line is at 1490C, where peritectic reaction takes place:Liquid + austenite
Second horizontal line is at 1130C, where eutectic reaction takes place:liquid austenite + cementite
Third horizontal line is at 723C, where eutectoid reaction takes place:austenite pearlite (mixture of ferrite & cementite).
61
The solid solution formed when carbon atoms are absorbed into the face-centred cubicstructure of iron is called Austenite and the extremely low level of solid solution formedwhen carbon dissolves in body-centred cubic iron is called Ferrite.
For many practical purposes we can regard ferrite as having the same properties as pureiron.the symbol ('gamma') is used to denote both the face-centred cubic form of iron and thesolid solution austenite, whilst the symbol ('alpha') is used to denote both thebody-centred cubic form of iron existing below 910C and the solid-solution ferrite
62
Definition of structures
Ferrite is known as solid solution. It is an interstitial solid solution of a small amount of carbon dissolved
in (BCC) iron. stable form of iron below 912 deg.C The maximum solubility is 0.025 % C at 723C and it dissolves only
0.008 % C at room temperature. It is the softest structure that appears on the diagram.
Ferrite is known as solid solution. It is an interstitial solid solution of a small amount of carbon dissolved
in (BCC) iron. stable form of iron below 912 deg.C The maximum solubility is 0.025 % C at 723C and it dissolves only
0.008 % C at room temperature. It is the softest structure that appears on the diagram.
Definition of structures
Pearlite is the eutectoid mixture containing 0.80% C and is formed at 723C on very slow cooling.
It is a very fine platelike or lamellar mixture offerrite and cementite.
The white ferritic background or matrix containsthin plates of cementite (dark).
64
Pearlite is the eutectoid mixture containing 0.80% C and is formed at 723C on very slow cooling.
It is a very fine platelike or lamellar mixture offerrite and cementite.
The white ferritic background or matrix containsthin plates of cementite (dark).
Austenite is an interstitial solid solution of Carbon dissolved in (F.C.C.) iron.Maximum solubility is 2.0 % C at 1130C.High formability, most of heat treatments begin with this single phase.It is normally not stable at room temperature. But, under certain conditions it is possibleto obtain austenite at room temperature.
Cementite or iron carbide, is very hard, brittle intermetalliccompound of iron & carbon, as Fe3C, contains 6.67 % C.It is the hardest structure that appears on the diagram,exact melting point unknown.Its crystal structure is orthorhombic. It is haslow tensile strength (approx. 5,000 psi), buthigh compressive strength.
65
Cementite or iron carbide, is very hard, brittle intermetalliccompound of iron & carbon, as Fe3C, contains 6.67 % C.It is the hardest structure that appears on the diagram,exact melting point unknown.Its crystal structure is orthorhombic. It is haslow tensile strength (approx. 5,000 psi), buthigh compressive strength.
Martensite - a super-saturated solid solution of carbon in ferrite.It is formed when steel is cooled so rapidly that the change from austenite to pearlite issuppressed.The interstitial carbon atoms distort the BCC ferrite into a BC-tetragonal structure(BCT).; responsible for the hardness of quenched steel.
Principal phases of steel and their Characteristics
Phase Crystal structure Characteristics
Ferrite BCC Soft, ductile, magnetic
Austenite FCC Soft, moderate strength,non-magnetic
Cementite Compound of Iron &Carbon Fe3CHard &brittleCementite Compound of Iron &Carbon Fe3CHard &brittle
Hypo-eutectoid steels: Steels having less than 0.8% carbon are called hypo-eutectoid steels (hypo means "less than").
Hyper-eutectoid steels (hyper means "greater than") are those that contain morethan the eutectoid amount of Carbon.
In arc welding, energy is transferred from the welding electrode to the basemetal by an electric arc.Heat input is a relative measure of the energy transferred per unit length ofweld.It is an important characteristic because, like preheat and interpass temperature,it influences the cooling rate, which may affect the mechanical properties andmetallurgical structure of the weld and the HAZ (see Figure 1). Heat input is typically calculated as the ratio of the power (i.e., voltage xcurrent) to the velocity of the heat source (i.e., the arc) as follows:
Cooling Rate is a Function of Heat Input
67
In arc welding, energy is transferred from the welding electrode to the basemetal by an electric arc.Heat input is a relative measure of the energy transferred per unit length ofweld.It is an important characteristic because, like preheat and interpass temperature,it influences the cooling rate, which may affect the mechanical properties andmetallurgical structure of the weld and the HAZ (see Figure 1). Heat input is typically calculated as the ratio of the power (i.e., voltage xcurrent) to the velocity of the heat source (i.e., the arc) as follows:
H = heat input (kJ/in or kJ/mm)E = arc voltage (volts)I = current (amps)S = travel speed (in/min or mm/min)
The effect of heat input on cooling rate is similar to that of the preheattemperature.As either the heat input or the preheat temperature increases, the rate of coolingdecreases for a given base metal thickness.
These two variables interact with others such as material thickness, specificheat, density, and thermal conductivity to influence the cooling rate.
The following proportionality function shows this relationship between preheattemperature, heat input and cooling rate:
68
The effect of heat input on cooling rate is similar to that of the preheattemperature.As either the heat input or the preheat temperature increases, the rate of coolingdecreases for a given base metal thickness.
These two variables interact with others such as material thickness, specificheat, density, and thermal conductivity to influence the cooling rate.
The following proportionality function shows this relationship between preheattemperature, heat input and cooling rate:
R = cooling rate (F/sec or C/sec)To = preheat temperature (F or C)H = heat input (kJ/in or kJ/mm)
69
The cooling rate is a primary factor that determines the final metallurgical structure of theweld and heat affected zone (HAZ), and is especially important with heat-treated steels.
When welding quenched and tempered steels, for example, slow cooling rates (resultingfrom high heat inputs) can soften the material adjacent to the weld, reducing the load-carrying capacity of the connection.