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Vol.57, No.7, 430 ~ 438, 2019
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| Title |
| PWHT Cracking Susceptibility in the HAZ of Martensitic 10Cr Steel for A-USC Power Plant |
| 김민정 Minjeong Kim , 강용준 Yongjoon Kang , 김남규 Namkyu Kim , 이상훈 Sanghoon Lee , 송상우 Sangwoo Song , 강남현 Namhyun Kang |
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| Abstract |
| In this study, the post-weld heat treatment (PWHT) cracking susceptibility in the heat affected zone (HAZ) of martensitic 10Cr steel was evaluated. The specimens taken from the 10Cr steel were thermally cycled using a Gleeble to simulate HAZ 1 (δ-ferrite) and HAZ 2 (single phase, γ). HAZ 2 had martensite and some M23C6-type carbides were present. On the other hand, HAZ 1 had martensite and the carbides were completely dissolved. In addition, δ-ferrite is observed in HAZ 1. The simulated HAZ specimens were stress rupture tested at a temperature range of 688-788 ℃ under stress of 150-450 MPa (21, 750-65, 250 psi). After the stress rupture test, a stress rupture parameter (SRP) was obtained using the rupture strength and ductility. In this way, the PWHT cracking susceptibility was evaluated through the SRP. Both HAZ 1 and HAZ 2 tended to increase rupture strength with decreasing PWHT temperature, but with a decrease in ductility. Also, it was noteworthy that the HAZ 1 had a lower PWHT cracking susceptibility than the HAZ 2 due to its higher rupture strength, despite its lower ductility. Because the precipitation strengthening occurs due to reprecipitation of MC-type carbide during PWHT.
(Received May 3, 2019; Accepted May 28, 2019) |
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| Key Words |
| martensitic 10cr steel, heat-affected zone, post-weld heat treatment, stress rupture test, δ-ferrite |
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