Microstructure and superelasticity of a biomedical β-type titanium alloy under various processing routes

Abstract

The influences of various processing routes including cold forging, suction casting, cold rolling, hot compression and hot forging on the microstructure, mechanical properties and superelasticity of Ti-7.5Nb-4Mo-2Sn alloy were investigated. It has been found that, the alloy processed by cold rolling, hot forging, cold forging and suction casting contained a single β phase, but the alloy after hot compression consisted of a duplex structure of α and β phases. The alloy exhibited an average grain size of about 4μm after suction casting processing, indicating excellent grain refining effect. A strong recrystallization texture {111}〈110〉 was well developed in the cold rolled and hot forged alloys; while cold forged and hot compressed alloys exhibited strong multiple textures in different directions associated with their deformation. Superelastic behavior was observed in the cold rolled, suction casted, hot forged and hot compressed alloys, in which the casted alloy exhibited the highest strain recovery rate which reached nearly 75%, and the hot compressed alloy showed higher stress for inducing martensitic transformation but lower recovery rate due to the complex multiple textures formed during hot compressing processing among the alloys after different processing routes.