Abstract: Effect of forming speed on microstructure, mechanical properties and fracture morphology of the 7050 aluminum alloy forgings was studied by metallographic microscope (OM), scanning electron microscope (SEM) and room temperature tensile test. The results show that with the increase of forming speed, the sectional morphology of grains of the alloy forgings gradually changes from round to elongated, with local coarsening. The tensile strength and yield strength increase first and then decrease with the increase of forming speed, and the elongation gradually decreases with the increase of forming speed. When the forming speed is 2 mm/s, the tensile strength and yield strength reach 608 MPa and 560 MPa respectively, and the elongation is 12.7%. When the forming speed is 2 mm/s and 8 mm/s, respectively, the fracture modes of the tensile specimens are mainly transgranular fracture, accompanied by a small amount of second-phase coarse particles and intergranular fracture. With the decrease of forming speed, the dimples increase in number and gradually in depth. The optimal selection of the forming speed for the hot forging die in real production is 2-8 mm/s.

Key words: 7050 aluminum alloy, forming speed, microstructure, mechanical properties, fracture morphology