Karpenko Physico-Mechanical InstituteKarpenko Physico-Mechanical Institute
Bay Zoltan Foundation for Applied Research Bay Zoltan Foundation for Applied Research
H.M. Nykyforchyn, O.Z. Student, G. Lenkey, A.D. Markov
STRENGTH OF POWER PLANT INSTALATIONS ELEMENTS AND
DURABILITY ANALYSIS BASED ON THE FRACTURE RISK
2nd Hungarian-Ukrainian Joint Conferenceon
SAFETY-REALIABILITY and RISK of
ENGINEERING PLANTS and COMPONENTS 19-21 September 2007, Kyiv, Ukraine
Introduction
Lifetime of structural element consists in:
at ambient temperatureCrack initiation stage → Crack propagation stage
at elevated temperatureMicrostructure change (because of diffusion) stage → Crack initiation stage → Crack propagation stage
Hydrogen intensifies diffusion and correspondingly accelerates microstructure change stage induced by diffusion processes
0 hours
190,000 hours110,000 hours
48,000 hours
Microstructure of the 12Kh1MF (0.1C-1.1Cr-0.26Mo-0.17V) steam Microstructure of the 12Kh1MF (0.1C-1.1Cr-0.26Mo-0.17V) steam pipeline steel depending of the service timepipeline steel depending of the service time
Tensile properties of the 12Kh1MF steel
op, hours
UTS, MPa
YS, MPa
, %
, %
H, MPa
0 470 280 29 75 1788
48000 436 237 33 66.4 1744
140000 453 251 27 77 1716
190000 460 258 25 77 17090 5 0 1 0 0 1 5 05 0
1 0 0
1 5 0
2 0 0
o p , 10 3 h
J, k
N/m
IS
The effect of operation time on fracture The effect of operation time on fracture toughness of the 12Kh1MF steeltoughness of the 12Kh1MF steel
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
K th
eff,
MP
am
1/2
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
K th
eff,
MP
am
1/2
Effect of the operation time Effect of the operation time орор (1) on the (1) on the parameter parameter Kth eff for the 12H1Kth eff for the 12H1ММF steelF steel
Fatigue crack growth rate across pipe wall at constant stress intensity factor range for steel after long term service
The method of high temperature degradation of steels -
thermocycling in hydrogenthermocycling in hydrogen
Microstructure of the 12Kh1MF (0.1C-1.1Cr-Microstructure of the 12Kh1MF (0.1C-1.1Cr-0.26Mo-0.17V)0.26Mo-0.17V) steam pipeline steel steam pipeline steel
depending of the numbers of thermocyclesdepending of the numbers of thermocycles
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
K th
eff,
MP
am
1/2
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
0 50 100 150 2002,0
2,5
3,0
3,5
0 50 100 150 200 250 300
2
1
op, h
n, thermocycle
K th
eff,
MP
am
1/2
Effect of the operation time Effect of the operation time орор (1) (1)
and number of thermocycles in and number of thermocycles in hydrogen n (2) on the parameter hydrogen n (2) on the parameter
KKth effth eff for the 12H1 for the 12H1ММF steelF steel
Crack growth direction
Operation
Thermocycling
Hardness of steam pipeline weld joint of exploited 200,000h (on left) and in initial state (on right)
The mechanical properties of weld metal (WM) in virgin state (light bars) and The mechanical properties of weld metal (WM) in virgin state (light bars) and after after ~2∙105 ~2∙105 h service time (dark bars). h service time (dark bars).
Figures indicate a percentage change of properties as a result of exploitationFigures indicate a percentage change of properties as a result of exploitation
Ultimate strength (σB) and yield strength (σ0,2) of base metal and weld metal on air (light bars)
and after hydrogen charging (dark bars)initial service initial service
OMOMOM
OM BM→ ←
Hydrogenation allows to reveal even base metal “in-bulk” degradation
Comparison of the mechanical parameters of metal state concerning its sensitivity Comparison of the mechanical parameters of metal state concerning its sensitivity to high temperature degradation of weld metal (a) and base metal (b): to high temperature degradation of weld metal (a) and base metal (b): l – l – relative relative
change of the corresponded parameters as a result of servicechange of the corresponded parameters as a result of service
0 1 2 3 4 5 6 70
100
200
300
400
500
air
initial state 30 TC 100 TC
, M
Pa
, mm
100
5
12
15
R5
50
3 6
6
3 parent metal
cladded metal
The parent AThe parent A-516 -516 GrGr.60 .60 steel was cladded withsteel was cladded with 410 410S ferritic S ferritic stainless steel (flyer)stainless steel (flyer)
Peculiarities of hydrogen effect on the creep process in the Cr-Ni steel
H2
air
Fracture of hydrogenated specimenin as received state
Fracture of hydrogenated specimenin degraded state
ELECTROCHEMICAL PARAMETERSELECTROCHEMICAL PARAMETERS
steam pipeline 12Kh1MF steelsteam pipeline 12Kh1MF steel
0,0 0,2 0,4 0,6 0,8 1,0
0,2
0,4
0,6
0,8
1,0
Pd
egra
d /P
virg
in
J1C degrad
/J1C virgin
Rp
jcor
jE=const
190,
000
h
degraded
140,
000
virg
in s
tate
12Kh1MF - 3% NaCl
0,6 0,7 0,8 0,9 1,0
0,2
0,4
0,6
0,8
1,0
Pd
egra
d /P
virg
in
Kth degrad
/Kth virgin
jcor
Rp
jE=const
190,
000
h
140,
000
degraded
virg
in s
tate
12Kh1MF - 3% NaCl
0,4
0,6
0,8
1,012Kh1MF - tap water
degraded190000 hour
Pde
grad
ed/P
virg
indegraded
140000 hour
Ecor
ba
jcor
Rp
Risk Based Maintenance and Risk Based Maintenance and Inspection (RBMI) ApproachInspection (RBMI) Approach
Allocation of the thermal fatigue cracks around the hole on the internal surface of the collector of water economizer
Risk matrix for the economizer collector after 18∙104 h of service (area 4D) and its predicted state after performing of the recommended works
(area 3С)
ConclusionsConclusions
1. The thermocycling of the material containing dissolved hydrogen is the effective rapid method for testing of high temperature degradation of steels.
2. The parameters of crack growth resistance are especially sensitive to high temperature metal degradation in the service and laboratory conditions.
3. Weld metal of steam pipeline steel is the most disposed to high-temperature degradation. In this case the tensile mechanical properties of strength and plasticity are sensitive enough to “in-bulk” material degradation. The revealed simultaneous reduction of strength and brittle fracture resistance is a phenomenon of in-service degradation. This phenomenon is strengthened by non-typical change of the parameters of plasticity: an elongation increases and reduction of area decreases with the weld metal service.
4. Hydrogen accelerates creep rate in the hydrocracking reactor shell steel. 5. A good correlation between changes of electrochemical and mechanical
parameters gives prospects for the development of NDT methods for evaluation of the current state of steels irrespective of the fact that material is exploited or not exploited in corrosion-hydrogenated environments.
6. The example of a usage of Risk Based Maintenance and Inspection (RBMI) Approach is presented concerning the collector of water economizer.