不同应变速率下TA15钛合金β形变过程中动态再结晶行为

Dynamic Recrystallization of Titanium Alloy TA15 during β Hot Process at Different Strain Rates

研究TA15钛合金在1050℃时,不同应变速率下变形过程中动态再结晶组织演变,讨论动态再结晶动力学、形核率和晶粒尺寸的演变规律。结果表明,随高低应变速率不同,存在两种类型的动态再结晶现象:连续动态再结晶和不连续动态再结晶。动力学分析应变速率为0.01,0.1,1s-1时,对应的动态再结晶稳态应变分别为1.26,1.57,2.93,说明增大应变速率则相应地提高稳态应变,在高应变速率条件下,往往难于达到稳态阶段。高应变速率下的形核率明显高于低应变速率下的形核率,且低应变速率下,较小幅度的增大应变速率就能使晶粒尺寸较大幅度下降;而在较高应变速率下,晶粒尺寸变化随应变速率改变较小。采用高应变速率及大应变下发生的连续动态再结晶可实现组织明显细化。

Dynamic recrystallization microstructure evolution of titanium alloy TA15 was investigated during deformation at 1050 oC and different strain rates.The dynamic recrystallization kinetics,nucleation rate and grain size evolution were discussed.Results show that with different strain rates there are two types of dynamic recrystallization,i.e.the continuous and the discontinuous.According to the dynamic analysis,at the strain rates of 0.01,0.1 and 1 s-1,the corresponded dynamic recrystallization steady strains are 1.26,1.57 and 2.93,indicating higher strain rates lead to higher steady strain.It is hard to reach steady stage at higher strain rates while the nucleation is obviously higher than that at lower strain rates.At lower strain rate,a slight increment of strain rates can greatly decrease the grain size;however,at higher strain rates,the grain size is little dependent on the strain rates.Therefore,refinement of structure can be obtained by the continuous dynamic recrystallization at high strain rate and large strain.