Study on Annealing Treatment and Basketweave Structure Deformation Mechanism of Laser Deposition Manufacturing TA15 Titanium Alloy

Abstract:

TA15 titanium alloy bulk specimens were prepared by spherical powder in the way of laser deposition manufacturing. The effect of alpha plus beta phase zone annealing treatment on mechanical properties, microstructure of laser deposition manufacturing TA15 titanium alloy and lamellar deformation mechanism has been studied by optical microstructure (OM) and scanning electron microscopy (SEM). The experimental results showed that microstructure was basketweave structure or near basketweave structure after alpha plus beta phase zone annealing treatment, pattern and size of alpha phase was affected effectively by annealing temperature. The mechanical properties after annealing still showed the anisotropy in the different direction: the strength was low and the plasticity was high in deposition direction and the strength was high and the plasticity was low in vertical deposition direction. The interlayer binding zone slip deformation played a vanguard role and the columnar crystal grain boundary had bound effect on alpha phase slip deformation. Microhardness was effected by the amount of alpha phase while it changed little with the increase of annealing temperature. Alpha lamellar in basketweave structure under the stress changed from near orthogonal to near parallel to the direction of stress, staggered arrangement of alpha lamellar generating resistance each other when it was in the state of slip deformation. Both deposition direction and vertical deposition direction had same tensile fracture modes which was ductile fracture after alpha plus beta phase zone annealing treatment.