Analysis Of Weld Thermal Cycle And Controlling Of Heat Input During Friction Stir Welding

In this paper,the NZ and HAZ temperature cycle were recorded by thethermocouple,then the results were analyzed by SAS software. The results show that thepeak temperature can be calculated by the follow formula：Tp/Tm=A(ω~k/v~α)βTm is temperature of metal melting temperature, k and α are associated with the locationof temperature measurement.For NZ α is zero and for HAZ α is one.The value of kdecrease with the increase of the distance form weld center.Four weld parameters with different welding heat input were designed to studymicrostructure and mechanical properties of welded joints. The results showed that GP ofHAZ decrease with the increase of heat input while the content of S-phase is almost nochange; the GP of NZ increase and the content of S-phase decrease with the increase ofheat input, it proves that the dissolve of S-phase and the reprecipitation of S-phase occur inNZ. With the increase of the welding heat input, the minimum hardness decrease in HAZand the value of hardness increase in NZ,when the weld parameter is1500-1000,thesoftening zone of joint is not exist,meanwhile, The maximum tensile strength of thewelded joint reach97%and elongation can reach67%of the base material. Themicro-tensile shows that tensile properities of NZ and TMAZ improve significantly withthe increase of heat input. And the gap between the regions of tensile properties becomesmaller,it expalation the coordination deformation of different region increase,thereforethe overall tensile property also increase.