Abstract
Heat treatment plays an important role in tailoring the mechanical properties of powder-metallurgy(PM)titanium alloys.However,only limited work about the rapid heat treatment(RHT)of PM titanium alloys has been reported.In this work,RHT was applied to PM Ti-5Al-5Mo-5V-1Cr-1Fe alloy after hot rolling to study the evolution of its mechanical properties and the influence of residual pores on its properties.Through hot rolling and annealing,a fine and uniform α+β structure with few residual pores is ob-tained.During RHT,the primary α dissolves gradually and completes in the β region,and the β grains then grow,resulting in the continuous decrease in elongation after aging.Moreover,the tensile strength first increases and then decreases with increasing RHT temperature,owing to the increase in volume fraction of secondary α in α+β region and the β grain growth in β region.In contrast to the RHT of cast-and-wrought titanium,the negative influence of residual pores lowers the RHT temperature for obtaining the highest tensile strength to a temperature below the β-transus temperature.Despite the negative influence of the residual pores,retained primary α and fine β grains with fine secondary αinside contribute to achieving a good strength/ductility balance(1570 MPa and 6.1％,respectively).Addi-tionally,although at higher cycles to failure,the negative influence of residual pores increases as it affects the crack initiation zone at the subsurface,the good resistance of secondary α to fatigue crack propaga-tion still enhances the fatigue strength considerably(about 300 MPa).This work suggests a cost-effective strategy to produce titanium alloys with high performance.
基金项目
College of Materials Science and Engineering,Jilin University,China()
National Academy of Sciences of Ukraine()
NETL
NSTL
万方数据