+ All Categories
Home > Documents > Soldadura de Aceros Duplex

Soldadura de Aceros Duplex

Date post: 03-Apr-2018
Category:
Upload: jaime-peralta-puma
View: 228 times
Download: 0 times
Share this document with a friend

of 14

Transcript
  • 7/29/2019 Soldadura de Aceros Duplex

    1/14

    1

    WELDABILITY AND JOINTNABILITY OFDUPLEX STAINLESS STEELS

    Prof. Dr. Srgio Duarte BrandiEscola Politcnica da Universidade de So

    Paulo, Departamento de EngenhariaMetalrgica e de Materiais

    [email protected]

    Abstract. Welding and joining of stainlesssteels, in particular of duplex stainless steels

    (DSS), has been one of the research lines of theWelding and Joining Group at Metallurgical andMaterials Engineering Department in University

    of So Paulo since 1992. This paper is a briefreport on the work done in this subject up to2012. Weldability studies of multipass welding at

    low temperature HAZ (LTHAZ) as well as at hightemperature HAZ (HTHAZ) and FZ (fusion zone)were conducted on samples of UNS S32101, S

    32304, UNS S31803, UNS S 32550, UNSS32750 and UNS 32760 DSS. Microstructure,mechanical and corrosion properties in

    simulated (dilatometer and or Gleebleequipment) and real welds were characterizedusing different techniques and tests.

    Intermetallic phase precipitation (sigma phaseand chromium nitride) and secondary austenitewere characterized and a model for secondary

    austenite precipitation in multipass welding ofHTHAZ was proposed. Simulated samples werecompared to real welds to validate the multipass

    thermal model and presented a very good

    agreement between them. Consequently thephase transformations studied by simulated

    samples represent real weld microstructure. Thebehavior of multipass FZ using filler metals(AWS E2259-17 and EN 25 9 4L) was also

    addressed. Intermetallic precipitation diagramswere determined for both filler metals and twoDSS to compare reheated weld metal regions

    for three different welding procedures. Thecrescent heat input technique presented thebest results. Some dissimilar welding studies

    using lean duplex, such as UNS S32101 andUNS S32304, and austenitic stainless steels

    (AISI 304L and AISI 316L), were also carriedout. Brazeability of UNS S32101, S32304,S31803, S32750 and UNS S32707 DSS wasalso considered. Experiments were carried out

    in a hydrogen continuous furnace using threedifferent nickel based filler metals (AWS BNi-1,BNi-2 and BNi-7). Several brazing conditions

    were tested using different brazeability testssuch as the sessile droplet test, the edge test,and the capillary raise test. Best wetting and

    spreading results were obtained for BNi-7 for theequipment used in the experiment, but brazing

    thermal cycling in such furnace impaired basemetal corrosion resistance due to intermetallicphase precipitation, except UNS S32101 and

    S32304.

    Introduction

    Weldability (and brazeability) of materials should

    be analyzed as an interaction among materials(base material, filler metal, and weld metal),welding/joining process (thermal, mechanical,

    and physico-chemical process characteristics),microstructure (FZ, PFZ, HAZ) and in-servicebehavior. Based in this approach, weldability

    studies in DSS were accomplished using realwelds and simulated samples of fusion weldingprocesses [1-6].

    To carry out theses studies DSS HAZ should be

    divided in two parts, low temperature HAZ(LTHAZ) and high temperature HAZ

    (HTHAZ)[2,3,7]. By low temperature one canunderstand a temperature range enough toavoid changes in the as -received microstructure

    of DSS plates, which is from 950to 650

    oC

    depending upon DSS type. In other words,LTHAZ is a region of HAZ which has minor

    changes in microstructure due to a small amountof intermetallic phases precipitation (chromiumnitride and sigma phase), usually not clearly

    observed by optical microscopy, but enough tomodify mechanical and/or corrosion behavior[2].

    On the other hand, HTHAZ is a region where as-received microstructure is completely modifiedand secondary austenite precipitation competeswith chromium nitride precipitation or dissolution,

    depending on the peak temperatures andcooling rates of subsequent welding passesduring fabrication of an equipment. As a rule,

    these temperatures range from solidustemperature to approximately 1000

    oC.

    Depending on the thermal cycle characteristics,

    intermetallic phases and/or secondary austenitecan precipitate and might change locally theDSS properties.

    Research results

    HAZ research.

    In the beginning, DSS weldability studies startedwelding UNS S31803 with autogenous one-passGTAW and EBW processes [1]. Heat inputs

    were calculated to give a recommended t1200-800[8] for GTAW weld bead (approximately 9 s) and

    mailto:[email protected]:[email protected]:[email protected]
  • 7/29/2019 Soldadura de Aceros Duplex

    2/14

    2

    a lowert1200-800 for EBW (0,3 s). The amount ofaustenite observed in FZ and in HTHAZ of these

    welds was (17 3) vol. % for GTAW and (3 1)vol. % in as-welded condition, whereas after 30min heat treatment at 1050

    oC volumetric fraction

    of austenite changed to (40 1) vol. % and (44

    2) vol. % , respectively. Results of mechanicaland corrosion properties of post welding heat

    treatment (PWHT) where similar to as-receivedplates. Figure 1 presents a result of generalizedcorrosion of EBW sample[9].

    Fig. 1 Generalized corrosion in an EBW joint. (a) As-welded condition; (b) PWHT condition. Opticalmicroscopy. 40X. [9]

    As PWHT is almost impractical for industrialconditions, the concept of a continuos PWHT

    during welding come to light, and multipasswelding issue was addressed in further researchstudies. The idea involved in this concept was to

    investigate the effect of multipass weldingthermal cycles in precipitation of intermetallicphases (sigma phase and chromium nitride);

    and recovering the volumetric fraction ofaustenite (by nucleating intergranular and

    intragranular secondary austenite in parallel withchromium nitride precipitation/dissolution) intomechanical and corrosion resistance of DSS.These phase transformations during welding

    characterize LTHAZ and HTHAZ of a DSS,respectively.

    LTHAZ research.

    UNS S 31803, S32550[2], S32304, S32750,

    and S32760[3] DSS samples were simulated in

    a dilatometer and in a Gleeble machine usinga thermal modeling for LTHAZ[2,10] assuming

    three passes at a place in the root joint, whichundergoes to a peak temperature of 950

    oC in

    the first pass, and using heat inputs from 0.4 to

    1.0 kJ/mm. Intermetallic phase precipitation wascharacterized by extracting precipitates bydissolving the DSS matrix and carrying out X-

    rays diffraction of extracted residues in a Debye-Scherrer chamber. Sigma phase and chromiumnitride precipitations were found in.

    S32550[2,11], S32750, and S32760[3]. On theother hand, UNS S 31803 and S32304

    simulated samples did not presented anyintermetallic precipitation detected by thistechnique. The amount of chromium nitride wascalculated for UNS S32550 and, it was

    measured an amount of 0.35 vol. % for 1.0kJ/mm[2,11]. Thus, ductility of simulatedsamples of UNS S 31803 and S32550 where

    compared using a bend test. Results arepresented in figure 2.

  • 7/29/2019 Soldadura de Aceros Duplex

    3/14

    3

    Fig. 2 Bended surface of simulated samples with 1.0 kJ/mm welding heat input. (a) UNS S31803; (b)UNS S32550. SEM.[2]

    Comparing figure 2(a) to figure 2(b) one cansee opened grain boundaries and interfaces insimulated sample of UNS S32550 due to

    intermetallic precipitation at these regions, whichwas confirmed by ASTM A262 practice Aintergranular corrosion test. Also, pitting

    corrosion resistance where measured usingartificial sea water and cyclic polarization tests attemperatures close to pitting potential critical

    temperatures. Results are presented in table 1.

    Table 1 Pitting and protection potentials for as-received and LTHAZ simulated samples of UNSS32304, S32750, and S32760. [3].

    Material Condition Pitt ing potential(mV, SCE)

    Protection potential(mV, SCE)

    UNS S32304 (25oC test

    temperature)

    as-received 487 73 -117 41

    simulated, 0.6 kJ/mm 531 37 -150 24simulated, 0.8 kJ/mm 459 32 -151 41

    simulated, 1.0 kJ/mm 481 24 -164 10

    UNS S32750(50

    oC test

    temperature)

    as-received 1008 21 299 284

    simulated, 0.6 kJ/mm 1073 25 -90 18

    simulated, 0.8 kJ/mm 1110 10 -67 27

    simulated, 1.0 kJ/mm 1083 11 -93 14

    UNS S32760(50

    oC test

    temperature)

    as-received 1030 37 409 138

    simulated, 0.6 kJ/mm 1090 17 307 13

    simulated, 0.8 kJ/mm 1053 25 250 29

    simulated, 1.0 kJ/mm 1060 17 256 46

    Analyzing table 1 one can note a significant dropin corrosion resistance observed for all heatinputs and materials studied compared to as-received condition, that is due to precipitation in

    LTHAZ.In summary, all these results are regarding toLTHAZ, which is, as previously mentioned, a

    region where almost no change in as-receivedmicrostructure is observed. Therefore, most of

    the research published in literature in DSSwelding is related to HTHAZ, which presents ahuge change in microstructure in this region.

    HTHAZ research.

    During a stay at The Ohio State

    University/Edison Welding Institute, a researchon simulated HAZ multipass welding of UNS

  • 7/29/2019 Soldadura de Aceros Duplex

    4/14

    4

    S32550 and UNS S32750 was conducted usinga simple thermal cycle model to investigate

    multipass welding effect on HAZ microstructureand mechanical and corrosion jointproperties[12,13]. Afterwards HTHAZ of UNS

    S32205, S32304, S32550, S32750, and S32760were studied using GTAW welding process and

    in a Gleeble equipment. A multipass thermal

    cycle model for HTHAZ [14] was developed,using a distributed heat sources methodologyproposed by Grong and isten [15], with a

    purpose of simulate HTHAZ samples.Fundamental aspects of intergranular andintragranular secondary austenite and chromium

    nitride precipitation were considered and amodel of intragranular secondary austeniteprecipitation was proposed. In this model, a

    cooperative precipitation of secondary austeniteand chromium nitride followed by nitridedissolution was proposed [4,16]. A scheme of

    this model is presented in figure 3.Based on thismodel [4,16], chromium nitrides first nucleate

    and precipitate at ferrite/austenite interface andgrowth into ferrite due to a favorable orientation

    among ferrite/chromium nitride/austenite. Duringprecipitation, the regions adjacent to precipitatesare depleted in ferrite stabilizers alloying

    elements, promoting austenite precipitation.Moreover, austenite has a higher nitrogensolubility and a dissolution of nitrides completely

    involved by austenite takes place duringmultipass welding [16]. Mechanical andcorrosion properties were related with secondary

    austenite precipitation. Charpy V absorbedenergy in multipass HTHAZ tends to be lowerthan as-received material[4]. Pitting corrosion

    resistance was determined by artificial sea watercyclic polarization curves and results showed anincrease in pitting potential with reheating after

    third pass and with increasing heat input.Results of pitting potential after third pass ofUNS S32550, S32750 and S32760 were almost

    the same of as-received plates[4].

    Fig. 3 Picture showing the dissolution of nitrides (white phase) in a secondary austenite region. Schemeof cooperative precipitation of secondary austenite and chromium nitride followed by nitridedissolution.[4,16]

  • 7/29/2019 Soldadura de Aceros Duplex

    5/14

    5

    FZ research.

    A similar research was conducted in fusion zoneof duplex stainless steels using two filler metals,

    AWS E2209-17 and EN 25 9 4L. A TTPdiagrams were obtained for these two fillermetals and also to two DSS (UNS S32750 and

    S32760). Comparing the results, filler metal EN25 9 4L presented the most favorable kinetic toprecipitate sigma and chi phases [5]. This

    means that the filler metal is more susceptible tointermetallic precipitation than base metals

    studied in this work, depending on weldingprocedure. Crescent heat input technique

    presented better results than other testedwelding techniques. Fig. 4 shows the result forthe weld metal submitted to three reheating

    thermal cycles.The effect of welding current frequency on theweld metal grain size was also studied for UNS

    S32101 and UNS S32304, which is depicted infigure 5. In this figure is also shown, for UNSS32102, EBSD images to compare grain size in

    a non-pulsed current and 20 Hz currentfrequency.

    Fig. 4 Picture showing the TTT sigma phase precipitation curve for weld metal from EN 25 9 4L andthee reheating thermal cycles and the microstructure of the weld metal in this region.[5]

    Analyzing figure 5 on can see a trend to

    increase the weld metal grain size of UNSS32101. On the other hand UNS S32304presented also a slightly trend to increase the

    grain size with the increase of the weldingcurrent frequency.

    To investigate these results, the nitrogen contentwas determined for each weld metal, for bothbase metals. The results are presented in table2.

    The loss of nitrogen was calculated based upon

    the original amount of the base metal beforewelding.The nitrogen loss increased with welding current

    frequency for both duplex stainless steels. UNSo nitrogen.S32101 presented a higher nitrogen

    loss than UNS S32304. This behavior might bedue to the different chemical composition. UNSS32304 has a higher amount of chromium,which has a higher chemical affinity

    AWS E 2610-17

  • 7/29/2019 Soldadura de Aceros Duplex

    6/14

    6

    Fig. 5 Effect of GTA welding current frequency on the grain size of UNS S 32101 and UNS S32304. In

    this figure is shown EBSD images of weld metal grain size for non-pulsed welding current and 20Hz

    welding current frequency. [18]

    Table 2 Nitrogen amount and nitrogen loss related to duplex stainless steel grades and differentwelding current frequency [18].

    UNS S32101 Nitrogen (%)Nitrogen

    lossUNS S32304 Nitrogen(%)

    Nitrogen

    loss

    Base metal 0,213 - Base metal 0,120 -

    no pulsed 0,153 0,060 no pulsed 0,080 0,040

    1 Hz 0,125 0,088 1 Hz 0,065 0,055

    5 Hz 0,110 0,103 5 Hz 0,064 0,056

    10 Hz 0,091 0,122 10 Hz 0,060 0,060

    20 Hz 0,110 0,103 20 Hz 0,047 0,073

    A multicomponent phase diagram for UNSS32101 was built up to confirm the effect of

    nitrogen in weld metal grain growth, aspresented in figure 6.

  • 7/29/2019 Soldadura de Aceros Duplex

    7/14

    7

    As the frequency increases, the amount ofnitrogen decreases and, as a consequence, the.

    temperature interval in the ferritic field increases.As the heat input is constant for all experiments,

    the cooling rate is almost the same. It means,the higher the interval, more time in the ferritic

    field, producing a larger grain size.

    Fig. 6 - Phase diagram of the LDSS UNS S32101, a) Complete phase diagram, b) Enlarged area of the

    ferritic field and the nitrogen loss according to welding current frequency, compared to base metal. [18]

  • 7/29/2019 Soldadura de Aceros Duplex

    8/14

    8

    Dissimilar welding research

    In some applications duplex stainless steels arewelded to other steels grades, such as carbonsteels or austenitic stainless steels. In figure 7 is

    shown a microstructure of a similar welded jointof UNS S32304 and a dissimilar welded joint ofUNS S3234 and AISI304. These materials were

    welded with coated electrode E2209-17.In figure 7 is also presented the result of ASTMA262 Practice A corrosion test in the regions

    indicated. The results indicates a sensitizedregion in the HAZ of UNS S32304 and in HAZ of

    AISI 304.

    Fig. 7 A similar and a dissimilar welded joint of UNS S32304 to AISI 304. In the picture is shown theresult of ASTM A262 Practice A corrosion test. [19]

    AISI 304 UNS S32304E2209-17

  • 7/29/2019 Soldadura de Aceros Duplex

    9/14

    9

    Brazeability research.

    Brazeability is a property which involves aspectsrelated to filler metal, base metal and itsinteraction with flux or atmosphere and thermal

    effects in base metal during brazing [6]. In otherwords, filler metal, base metal and brazingprocess characteristics should be chosen in

    such a way that no embrittlement of base metaloccurred during brazing, liquid metal flowthrough all the joint gap and joint region

    protected by flux or suitable atmosphere. Basedon this definition, brazing temperature shouldavoid Change in volumetric fraction indicates

    that other phases might precipitate dependingon temperature and time during brazing thermalcycle. For UNS S31803 the temperature range

    to be avoided is from 950 to 700oC, due to

    sigma phase precipitation in base metal. The

    best brazing temperature for duplex stainlesssteels is around the heat treatment at 1050

    oC.

    Temperatures higher than this can produce achange in ferrite/austenite balance and might

    produce nitride precipitation. For this reason,brazing thermal cycle should be carefullydesigned to avoid embrittlement in the whole

    component. As duplex stainless steels have agood corrosion resistance, the brazing fillermetal should have also a good corrosion

    resistance. Nickel base filler metals present

    good corrosion resistance and a suitable brazingtemperature range. Nickel base filler metals are

    alloyed with boron and silicon (BNi-2) andphosphorus (BNi-7) to reduce brazingtemperature [6]. These elements also affect

    liquid viscosity and, as a consequence, gap jointfilling extension. Each filler metal presents anideal clearance to provide a defect free joint. All

    these aspects together characterize brazeabilityof a material. In other words, contact angle,spreading final area, ideal joint clearance

    determined by edge test, and phasetransformation in base metal during brazingthermal cycle are important to characterize

    brazeability.

    Brazing of UNS S31803 DSS was done in acontinuous furnace under a pure hydrogen

    atmosphere and using different brazing fillermetals, BNi-2 and BNi-7 at 1100

    oC. Brazing

    parameters were changed to produce differentbrazing and after-brazing cooling times. Resultsshowed that BNi-7 presented better wettabilityresults than BNi-2 [6]. However the cooling time

    after brazing was low enough to deteriorate DSSbase metal, producing approximately 10% ofsigma phase. Based on this result, continuous

    furnace brazing are not suitable for UNS S31803DSS brazing, unless a cooling system might beused to reduce cooling time and avoid sigma

    phase precipitation[6].

    Fig. 8 Relationship between joint strength and joint gap [6].

  • 7/29/2019 Soldadura de Aceros Duplex

    10/14

    10

    Edge test provides important informationregarding to ideal brazing joint clearance. The

    minimum joint clearance that produces a jointcompleted filled and the maximum gap whereeutectic phase in the center of joint is

    discontinuous define this ideal range. In thecase of duplex stainless steels there is a fccnickel rich phase adjacent to base metal and a

    eutectic with hard and brittle phases in themiddle of the joint. There is a strong correlationbetween the microstructure and the mechanical

    properties of a brazed joint. The mechanicalstrength of a brazed joint is achieved when thegap is into the ideal gap range. Figure 2

    presents an schematic plot of the strength of thejoint as a function of the joint gap. Region 1presents a drop in the mechanical properties

    due to a lack of joint filling, reducing the brazedarea in the joint. Region 2 shows the higher

    strength, due to the Ni rich continuous

    phase in the gap and also due to a mechanicalconstraint produced by a triaxial stress state.

    Region 3 depicts a region with the eutecticphase in the joint middle, producing amechanical resistance close to the filler metal.

    Figure 9 presents a microstructure of a non idealgap of a UNS S31803 brazed joint with BNi-2filler metal. In figure 3(a) one can see the rich

    nickel phase at brazed joint/base metal interfaceand some rich in silicon and/or boron phases,represented by the dark grey phases. Figure

    3(b) shows a precipitation of intermetallicphases in base metal. These phases are sigmaphase and boron rich phases. During brazing,

    boron can diffuse to base metal faster thansilicon and phosphorus.

    (a)

    (b)

    Fig. 9 Brazed joint of UNS S31803 with BNi-2. (a) shows the microstructure of the brazed joint. (b)depicts the intermetallic phases produced during brazing in base metal. Back scattered electronspictures.

  • 7/29/2019 Soldadura de Aceros Duplex

    11/14

    11

    Figure 10 shows a microstructure of a brazedjoint of a UNS S31803 joined with BNi -7 filler

    metal. In figure 4(a) one can see the rich nickelphase at brazed joint/base metal interface andsome phosphorus rich phases. Figure 4(b)

    depicts a back scattered electrons picture of thejoint. The light gray in the joint was identified by

    microanalysis as (Ni,Cr,Fe)P and the dark grayas (Ni,Cr,Fe)3P. Sigma phase precipitation was

    also observed in these brazed samples.

    (a)

    (b)

    Fig. 10 Brazed joint of UNS S31803 with BNi-7. (a) shows the microstructure of the brazed joint. Etch:10% oxalic acid. (b) depicts the intermetallic phases produced in the brazed gap. Back scatteredelectrons picture.

    A EBSD technique was utilized to characterizeferrite and austenite in UNS S32750 joined with

    BNi-2 brazing filler metal. Results are presentedin figure 11.

  • 7/29/2019 Soldadura de Aceros Duplex

    12/14

    12

    Figure 11(a) shows the presence of a largeamount of nickel rich phase in the eutectic

    phase, as previously presented.

    (a)

    (b)

    Fig. 11 EBSD image of ferrite and austenite in the brazed joint of UNS S32750 with BNi-2. (a) shows

    austenite and ferrite as solid colors. (b) depicts the region characterized by EBSD technique. Backscattered electrons picture.

  • 7/29/2019 Soldadura de Aceros Duplex

    13/14

    13

    Final comments

    This paper is an overview of the research done atUniversity of So Paulo in weldability and jointability

    of DSS in the last 10 years. Details of tests and

    additional results and discussions can be found inthe mentioned literature.

    Acknowledgments

    Author would like to acknowledge his students

    (Antonio, Claudia, Ricardo, Clvis, Vinicius,Francisco, Adriano, Marcos, Reginaldo, Alcio, Jos

    Antonio, Silveli),which make these ideas come

    through. Also I appreciate FAPESP and CAPES forfunding these works.

    References

    [1] S.D. Brandi. Weldability study of duplex

    stainless steel DIN W.Nr. 1.4462 (UNS S31803)

    (PhD thesis, University of So Paulo, SP, Brazil,

    1992, 265 pgs). in Portuguese

    [2] A. J. Ramirez Londoo. Precipitation studies of

    chromium nitride and sigma phase b y thermal

    simulation of multipass heat affected zone of duplex

    stainless steels (MSc thesis, University of SoPaulo, SP, Brazil, 1997, 151 pgs). in Portuguese

    [3] C. P. Serna Giraldo. Intermetallic phases

    precipitation at low temperature heat affected zone

    of duplex stainless steels multipass welding (MSc

    thesis, University of So Paulo, SP, Brazil, 2001,

    123 pgs). in Portuguese

    [4] A. J. Ramirez Londoo. Intermetallic phases

    and secondary austenite precipitation at multipass

    heat affected zone of duplex stainless steels) (PhD

    thesis, University of So Paulo, SP, Brazil, 2001,

    241 pgs). in Portuguese

    [5] R.A. Fedele. Heat input influence on multipass

    fusion zone performance of duplex stainless steels.

    (MSc thesis, University of So Paulo, SP, Brazil,

    2001, 175 pgs). in Portuguese

    [6] C. Carvalho Jr. Braseability studies of duplex

    stainless steel using nickel base filler metals. (MSc

    thesis, University of So Paulo, SP, Brazil, 1999,

    135 pgs). in Portuguese

    [7] J.C Lippold; W. Lin; S.D. Brandi; W.A.

    Baeslack III; I. Varol - "A review of heat affected

    zone microstructure and properties of duplex

    stainless steels". IN: Proceedings, Conference on

    Duplex Stainless Steels, Glasgow, Scotland, 1994,

    paper 118.

    [8] J. Honeycomb; T.G.Gooch Arc welding

    ferritic-austenitic stainless steels (Welding Institute

    Res. report 286/1985)

    [9] S.D. Brandi; A.F. Padilha; S. Wolynec, -

    Corrosion resistance of GTAW and EBW welded

    joints of DIN W. Nr. 1.4462 (UNS S31803): Effect of

    post weld heat treatment. IN: Proceedings,

    Offshore Mechanics and Artic Engineering, OMAE

    96; Florence, Italy; 18-21 July, 1996; p. 309-322.

    [10] A.J Ramirez Londoo,.; S.D. Brandi, A

    proposed modification of Rosenthals Solution of

    heat transfer equation to simulate multipass welding

    of duplex stainless steels. IN: Proceedings,

    International Conference Trends in welding

    research, AWS e ASM, Georgia, EUA, 1-5 June

    1998, pg 19-24.

    [11] S.D. Brandi,; A.J. Ramirez-Londoo, -

    Precipitation of intermetallic phases in the HAZ of

    multipass welding of duplex and super-duplex

    stainless steels. IN: Proceedings, Duplex 97

    International Conference, Maastricht, Holand, 21-23

    October 1997 , pg. 405-410.

    [12] S.D. Brandi, J.C.Lippold, W. Lin, - The

    corrosion resistance of simulated multipass welds of

    duplex and super-duplex stainless steels. IN:

    Proceedings, Duplex 97 International Conference,

    Maastricht, Holand, 21-23 October 1997, pg. 411-

    418.

    [13] S.D. Brandi; J.C. Lippold Effect of Interpass

    temperature on the heat-affected zone performance

    of simulated multipass welds in duplex and

    superduplex stainless steels (EWI Summary Report

    SR 9707, November 1997, 4 pgs.)

    [14] A.J Ramirez Londoo; J.C. Lippold; S.D.

    Brandi "Application of puntiforme heat sources

    discrete distribution to simulate multipass welding

    heat flow". Submitted to Science and Technology of

    Welding and Joining, 2003.

  • 7/29/2019 Soldadura de Aceros Duplex

    14/14

    14

    [15] O. Grong Metallurgical modeling of welding

    (The Institute of Materials, London, 1994, pg 77-80).

    [16] A.J Ramirez Londoo; J.C. Lippold; S.D.

    Brandi "The Relationship between Chromium

    Nitride and Secondary Austenite Precipitation in

    Duplex Stainless Steels". Paper submitted to Met.

    Trans., 2003.

    [17] S.D Brandi; C. Carvalho Jr, Brazability of

    UNS S31803 duplex stainless steels by nickel base

    filler metals in a continuous furnace brazing". IN:

    Proceedings, International Brazing and Soldering

    Conference "IBSC 2000", American Welding

    Society, Albuquerque, New Mexico, 2000, p.162-

    169.

    [18] Vargas G, E. R., Brandi, S.D. - Behavior of

    grain size in the weld bead of lean duplex stainless

    steel UNS S32101 and UNS S32304 using pulsed

    GTAW process. MSc thesis, USP, 2010.

    [19] Assis, C. A. - Comparao da junta similar de

    ao inoxidvel duplex UNS S32304 com a junta

    dissimilar de ao inoxidvel duplex UNS S32304

    com ao inoxidvel AISI 304, soldadas com E2209-

    17.


Recommended