Investigation of Dynamic Mechanical Behavior and Damage Characteristics in TC32 Alloy

Abstract

The dynamic shearing experiment was been done by using split Hopkinson pressure bar(SHPB) technique in TC32 alloy with lamellar, bimodal and basket microstructures. The damage Characteristics of TC32 alloy was investigated by using optical microscope(OP) and scanning electron microscopy(SEM). The results show that the critical fracture velocity is 2400 s-1, 2700 s-1, and 2600 s-1 for lamellar, bimodal, and basket microstructures respectively. The bimodal microstructure exhibit the best Dynamic mechanical behavior compared with the other two microstructures. Adiabatic shear bands(ASBs) and microvoids initiation, growth, and coalescence to damage in adiabatic shear bands(ASBs) were observed in all of three microstructures. Also, microvoids initiation and growth are prior to the interface between ASBs and matrix. Investigation indicated that plastic flow characteristic is not obvious at the interface between ASBs and matrix, which observed long crack in lamellar microstructure. In bimodal microstructure, fibrous a adiabatic shear bands(ASBs) and surrounding region are shown. Because of strong shear deformation, the plastic flow characteristic appears clearly, and primary α phase was elongated. Microvoids initiation is also prior to the α/β phase boundaries. The damage characteristics of basket microstructure are similar to bimodal microstructure. But unlike lamellar and basket microstructures, the microvoids are initiatied when the acicular primary α phase arranged in order is perpendicular to the adiabatic shear bands(ASBs) in lamellar microstructure. ASBs is mostly consisted of equiaxed grains, and the deformation mechanism still wasn't defined.

Keywords

• titanium alloy
• adiabatic shear band
• damage characteristics