Effect of Sensitization Treatment on Hydrogen Embrittlement Cracking of Duplex Stainless Steel
Keisuke KUROSE, Hideo CHO, Takeshi OGAWA and Mikio TAKEMOTO
Abstract:This study aims to evaluate characteristics of hydrogen embrittlement cracking (HEC) of sensitized duplex stainless steel with simulated heat-affected zone (HAZ). The HEC of the steels, aged for 20hr at 650ºC, 750ºC and 800ºC, were studied using a testing machine which can control the stress intensity factor, K, for the precracked compact type (CT) specimens subjected to hydrogen charging. Fracture mechanisms were studied by acoustic emission (AE) method in conjunction with metallographic observation. Fracture toughness, Kc, for the steel aged at 650ºC was higher than those of others. The steel aged at 650ºC, with hardened ferrite phase, suffered hydrogen-induced brittle cracks in front of main crack, while austenite phase exhibited ductile fracture. For the steels aged at 750ºC and 800ºC, both the ferrite and sigma phase suffered hydrogen-induced microcracks. Key Words:Duplex stainless steel, Heat-affected zone, Hydrogen embrittlement cracking, Ferrite phase, Sigma phase, Acoustic emission