| As a solid-state welding, friction stir welding(FSW) of titanium alloy effectively avoidsthe defects and shortcomings of the traditional welding。 In this paper, the causes of tool wearduring FSW process and the solutions were analyzed. The process of friction stir welding withextra auxiliary heating source was investigated.By using the finite element software ABAQUS, the temperature field and the stress fieldof2mm thick TC4titanium alloy under traditional FSW and auxiliary heating FSW weresimulated. The numerical simulation results show that so long as reasonable weldingprocedure parameters are adopted, peak temperature of auxiliary heating FSW is nearly thesame as that of traditional FSW. By adjusting the welding parameters under auxiliary heatingFSW process, residual stress of FSW joint reduces.The device for auxiliary heating FSW was designed. The gas shield was designed forTC4titanium alloy was easily reacted with the composition of air in different temperature.Because TC4titanium alloy is high temperature alloy, welding jig was redesigned to avoidadhesions phenomenon between the welding plate and backing plate during FSW. Meanwhile,in order to reduce the "upsetting" of W-Re tool, the method of a preset hole is used to weld2mm thick TC4titanium alloy and then a single W-Re tool can join a FSW weld with thelength of2.2m.Mechanical properties and microstructure of joint under traditional FSW and auxiliaryheating FSW was discussed. The research results show that when the tool’s rotational speedwas200rpm and welding speed was50mm/min, tensile strength and elongation of joint underauxiliary heating FSW is nearly the same as that under traditional FSW. Under auxiliaryheating FSW, dimples are relatively even and dimple nested phenomenon appears in someregion of joint. |
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