Mathematical modelling of joint temperature during linear friction welding of dissimilar Ti-6.5Al-3.5Mo-1.5Zr-0.3Si and Ti-5Al-2Sn-2Zr-4Mo-4Cr alloys

The linear friction welding (LFW) of dissimilar titanium alloys Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (Ti11) and Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti17) was studied. Combined with experimentally recorded temperature of the specimen, the thermal history of the joint during LFW was calculated based on the equation of heat conduction. The calculated temperatures are comparable to those in experiment indicating that the proposed mathematic calculation method is appropriate to use for LFW. The highest temperature of the interface was about 1280oC and the time spent above the b transus temperature being about 4.5s in Ti17 side and 3.8s in Ti11 side, respectively. The highest temperatures of the TMAZs in Ti17 and Ti11 sides are about 1100°C and 1110°C, respectively. The cooling rate is about 250°C/s and 400°C/s in the interface and TMAZs. Fine equiaxed grains are present in the WZ, and numerous elongated grains are present in the TMAZs in both sides except a small number of fine recrystallized grains.