Study of in-situ formation of Fe-Mn-Si shape memory alloy welding seam by laser welding with filler powder

被引：12

作者：

Ju, Heng ^{[1
]}

Lin, Chengxin ^{[1
]}

Liu, Zhijie ^{[1
]}

Zhang, Jiaqi ^{[1
]}

机构：

[1] Dalian Maritime Univ, Transportat Equipment & Ocean Engn Coll, Dalian 116026, Peoples R China

来源：

OPTICS AND LASER TECHNOLOGY | 2018年 / 104卷

关键词：

Laser welding; Filler powder; Restrained mixing uniform design method; Fe-Mn-Si shape memory alloy welding seam; Mechanical properties; Stress-induced gamma -> epsilon martensite transformation; RESIDUAL-STRESS; LAP JOINT;

D O I：

10.1016/j.optlastec.2018.01.062

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

To reduce the residual stresses and improve the mechanical properties of laser weldments, produced with the restrained mixing uniform design method, a Fe-Mn-Si shape memory alloy (SMA) welding seam was formed inside the 304 stainless steel by laser welding with powder filling. The mass fraction, shape memory effect, and phase composition of the welding seam was measured by SEM-EDS (photometric analyser), bending recovery method, and XRD, respectively. An optical microscope was used to observe the microstructure of the Fe-Mn-Si SMA welding seam by solid solution and pre-deformation treatment. Meanwhile, the mechanical properties (residual stress distribution, tensile strength, microhardness and fatigue strength) of the laser welded specimen with an Fe-Mn-Si SMA welding seam (experimental material) and a 304 stainless steel welding seam (contrast material) were measured by a tensile testing machine hole drilling method and full cycle bending fatigue test. The results show that Fel5Mn5Si12Cr6Ni SMA welding seam was formed in situ with shape memory effect and stress induced gamma -> epsilon martensite phase transformation characteristic. The residual stress of the experimental material is lower than that of the contrast material. The former has larger tensile strength, longer elongation and higher microhardness than the latter has. The experimental material and contrast material possess 249 and 136 bending fatigue cycles at the strain of 6%, respectively. The mechanisms by which mechanical properties of the experimental material are strengthened includes (1) release of the residual stress inside the Fe-Mn-Si SMA welding seam due to the stress-induced gamma -> epsilon martensite phase transformation and (2) energy absorption and plastic slip restraint due to the deformations in martensite and reverse phase transformation. (C) 2018 Elsevier Ltd. All rights reserved.

引用

页码：65 / 72

页数：8