三重热处理对径向锻造Ti-6Al-4V钛合金组织和性能的影响

Effect of Triple Heat Treatment on Microstructure and Properties of Radial Forged Ti-6Al-4V Titanium Alloy

研究了几种三重热处理制度对径向锻造Ti-6Al-4V钛合金棒材组织和性能的影响。结果表明,在接近相变点进行三重热处理时,组织为网篮状组织;第一重热处理形成的网篮组织,经过两相区的二重固溶和三重时效后组织状态变化不大;随着固溶温度的增加,合金的强度逐渐上升,且距相变点越近,增加的幅度越大;伸长率和断面收缩率有下降趋势,在接近相变点时,下降幅度更大。在两相区进行三重热处理时,Ti-6Al-4V钛合金组织是典型的双态组织,包括近等轴α相和β转变组织,β转变组织内部为针状的次生α相和残余β相;当固溶温度在920~950℃时,强度和塑性呈现出良好的匹配关系,在热处理制度为950℃/1 h,AC+950℃/1 h,OQ+560℃/4 h,AC时,材料获得最佳高强度和高塑性匹配关系。

The influence of several triple heat treatment processes on the microstructure and properties of radial forged Ti-6Al-4V titanium alloy bar was studied.The results show that when subjected to triple heat treatment near the phase transition point,the microstructure is a basket like structure.The basketweave microstructure formed at the first heat treatment undergoes the second solid solution in the two-phase zone and the third aging,and there is little change in the microstructure state.As the solid solution temperature increases,the strength of the alloy gradually increases,and the closer it is to the phase transition point,the greater the magnitude of the increase;the elongation and reduction of area have a decreasing trend,and the decrease is bigger when the temperature approaches the phase transition point.When conducting triple heat treatment in the two-phase region,the microstructure of Ti-6Al-4V titanium alloy is typical two-state structure,including the isoaxialα-phase and transformedβ,and the inner of the transformedβis the acicular secondaryα-phase and residualβ-phase.When the solid solution temperature is 920-950℃,there is a good matching relationship between strength and plasticity.When the heat treatment process is 950℃/1 h,AC+950℃/1 h,OQ+560℃/4 h,AC,the material obtains the best matching relationship between high strength and high plasticity.