Microstructure and properties of SiCp/6061-T6Al MMCs low-power laser-TIG hybrid welding based on Ti intermediate layer

Abstract:

Abstract: Using Ti foil with thickness of 0.1 mm as the interlayer, SiCp/6061-T6 Al MMCs was welded by employing low-power laser-TIG hybrid welding. After welding experiment, the macro morphology, microstructure, phase, resistivity, tensile strength and fracture morphology of the joint were analyzed. The results showed that laser power had significant influence on the formability of welding seam. Ti foil can basically suppress the formation of needle-like Al4C3 in weld seam. Meanwhile, some new phases such as TiC reinforcement phase and strip-like TiAl3 were generated in welding seam. The morphology of weld zone and fusion zone were characterized by equiaxed crystal and columnar crystal, respectively. The microstructure in heat-affected zone did not change obviously. The joint resistivity increased with the increasing of laser power and the value of joint resistivity was significantly higher than that in base material. The joint tensile strength achieved 196.98 MPa, which was equal to 54.71% of base material, when laser power of 554 W was applied. There were almost no pores in joint fracture and the second phase particle in dimple was mainly composed of TiC. The joint displayed the characteristics of brittle-ductile mixed fracture which was dominated by brittle fracture.

Key words:SiCp/6061-T6Al composite material; Laser-TIG hybrid welding; Ti foil intermediate layer; microstructure; performance;