PSI - Issue 42

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000 – 000 tr t r l I t rit r i ( ) Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ il l li t . i i t.

www.elsevier.com/locate/procedia . l i r. /l t / r i

ScienceDirect

Procedia Structural Integrity 42 (2022) 155–162

© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 Abstract Martensitic stainless steel 17-4PH is a precipitation hardening material with a combination of high strength and good ductility and has been widely used in various modern industries. However, it is also susceptible to hydrogen embrittlement in some environments. In this paper, susceptibility to hydrogen embrittlement in this material with different conditions has been studied using a slow strain rate tensile test with an in-situ electrochemical hydrogen charging. By fracture and microstructure analysis, the hydrogen embrittlement mechanisms have been evaluated. It was found that the 17-4PH steel in the solution annealed condition is susceptible to hydrogen embrittlement. Hydrogen-enhanced decohesion (HEDE) is the main hydrogen embrittlement mechanism. Tempering at 510 °C reduces susceptibility to hydrogen embrittlement by precipitation of different nano precipitates, mainly nano Cu rich phase and nano austenitic phase. This also leads to a transition of hydrogen embrittlement mechanism from HEDE to HELP (hydrogen enhanced localized plasticity). A synergetic effect of HELP and HEDE has been observed. This work increases the knowledge to reduce and finally avoid susceptibility to hydrogen embrittlement in 17-4PH steel material. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23 Keywords: Hydrogen embrittlement; martensitic stainless steel; fracture mechanism; intergranular fracture; microstructure 1. Introduction Martensitic stainless steel 17-4PH is a precipitation hardening material with nano copper rich particles in the martensitic matrix. This material shows a good combination of high tensile strength, good fracture toughness and corrosion resistance and has been widely used in various modern industries such as nuclear, chemical, aircraft and naval industries, Smith (1993), Farrar (2004) and Viswanathan et al. (1988). However, this material has been reported t iti t i l t l i i it ti i t i l it i ti i t t tilit i l i i i t i . , it i l ti l t ittl t i i t . t i , ti ilit t ittl t i t i t i l it i t iti t i i l t i t t il t t it i it l t i l i . t i t t l i , t ittl t i l t . t t t t t l i t l ti l iti i ti l t ittl t. i i t i ittl t i . i t ti ilit t ittl t i it ti i t i it t , i l i t iti . i l l t t iti ittl t i t l li l ti it . ti t . i i t l t i ll i ti ilit t ittl t i t l t i l. uth . li l i . . This i ti l t li tt :// ti . /li / / . / Peer i i ilit of 23 European Conference on Fra t : r rittl t; rt iti t i l t l; fr t r i ; i t r r l r fr t r ; i r tr t r . i t iti t i l t l i i it ti i t i l it i ti l i t t iti t i . i t i l i ti i t il t t , t t i i t i l i i i t i l , i l, i t l i t i , it , i t t l. . , t i t i l t 23 European Conference on Fracture - ECF23 Microstructures and hydrogen embrittlement fracture mechanisms in 17-4PH martensitic stainless steel Guocai Chai a,b,* , Tomas Antonsson a , Sten Wessman c and Lena Ryde c a Engineering Materials, Linköping University, 581 83 Linköping, Sweden b Sandvik Materials Technology, SE-811 81 Sandviken, Sweden c Swerim, 164 40 Kista, Sweden *guocai.chai@alleima.com ocai Chai a,b,* a c c a i i t i l , i i i it , i i , b i t i l l , - i , c i , i t , i. i ll i .

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23 l i r . . i i rti l r t - - li ( tt :// r ti . r /li / - - / . /) i i ilit t - t r . li

2452-3216 © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 10.1016/j.prostr.2022.12.019