Effect of Ta interlayer on laser welding of NiTi to AISI 316L stainless steel

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• 作者：C.H. Ng^a ; Edwin S.H. Mok^b ; H.C. Man^a ; ^{hc.man@polyu.edu.hk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Laser welding ; NiTi ; Stainless steel ; Tantalum ; Interlayer ; Tensile behavior
• 刊名：Journal of Materials Processing Technology
• 出版年：2015
• 出版时间：December 2015
• 年：2015
• 卷：226
• 期：Complete
• 页码：69-77
• 全文大小：7877 K

文摘

To improve the quality of the weldment between nickel titanium (NiTi) and AISI 316L stainless steel wires, laser welding with tantalum interlayer was attempted by means of a fiber laser system. The presence of Ta interlayer and its thickness were found to have a significant effect on the chemical composition, microstructure and mechanical properties of laser-welded NiTi-316SS joints. By increasing the Ta content in the weld joint, the content of brittle intermetallic compounds (TiFe₄, TiCr_2, TiFe, etc.) was reduced. The tensile stress and strain of the welded joints at fracture reached 251 MPa and 2.7% by adding a 50-渭m Ta interlayer, as compared to the weldment of NiTi to AISI 316L stainless steel (134 MPa and 0.63%) without Ta interlayer. With excessive (>50 渭m) Ta addition in the weld joint, the mechanical properties deteriorated due to the excessive formation of new intermetallic phases TaCr₂ and Ni₃Ta, and the fracture region was at the weld-316L SS interface, where cracks were formed during tensile testing.