Reduction of environmentally induced cracking of laser-welded shape memory NiTi wires via post-weld heat-treatment

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:588

Article

Chan, C. W.¹  Man, H. C.² 

[1] Queens Univ Belfast, Sch Mech & Aerosp Engn, Belfast BT7 1NN, Antrim, North Ireland

[2] Hong Kong Polytech Univ, Dept Ind & Syst Engn, Kowloon, Hong Kong, Peoples R China

关键词: Post-weld heat-treatment;    Hydrogen embrittlement;    Shape memory alloys;    Laser welding;    NiTi;   

DOI  :  10.1016/j.msea.2013.09.051

来源: Elsevier

【 摘 要 】

In this study, the environmentally induced cracking behavior of the NiTi weldment with and without post-weld heat-treatment (PWHT) in Hanks' solution at 37.5 degrees C at OCP was studied by tensile and cyclic slow-strain-rate tests (SSRT), and compared with those tested in oil (an inert environment). Our previous results in the tensile and cyclic SSRT showed that the weldment without PWHT showed high susceptibility to the hydrogen cracking, as evidenced by the degradation of tensile and super-elastic properties when testing in Hanks' solution. The weldment after PWHT was much less susceptible to hydrogen attack in Hanks' solution as no obvious degradation in the tensile and super-elastic properties was observed, and only a very small amount of micro-cracks were found in the fracture surface. The susceptibility to hydrogen cracking of the NiTi weldment could be alleviated by applying PWHT at the optimized temperature of 350 degrees C after laser welding. (C) 2013 Elsevier B.V. All rights reserved.

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