Similar and Dissimilar Nd:YAGlaser Welding of NiTi Shape Memory Alloy to AISI 420Stainless Steel

Abstract

Similar NiTi shape memory alloy(SMA) plates, 420 Martensitic stainless steelplates and dissimilar NiTi shape memory alloy with Martensiticstainless steel were welded by a pulsed Nd:YAGlaser welding method.The nature microstructure of the base metal (BM), weld zone (WZ), interface and the heat affected zones(HAZ) were showedby in a scanning electron microscope (SEM) and optical microscope.Vickers hardness tests wasconducted to specifythe properties of the weld. The outcomes showed that the hardness of dissimilar NiTi-Stainless steel (St.St.) weld is higher than that in similar NiTi-NiTi and St.St.-St.St. weld.TheMicrostructural examination in both NiTi-St.St. and NiTi-NiTi welds illustrates that the solidification process in the fusion zone changed the kind of plan to the cell type as well as the changes that occur in the cell to dentritic kind of intra- region of the weld through the weld center in the welded sample sides but in the St.St.-St.St. weld showed dendrite microstructure. In this study it is found that the increase of the welding speed leads to a decrease in hardness in all jointsNiTi-NiTi, NiTi-St.St. and St.St.-St.St.