应变对β固溶Ti-55531合金室温压缩变形机制的影响

Effect of Strain on Compression Mechanism of Ti-55531 Alloy at Room Temperature

研究应变对β固溶处理后Ti-55531合金室温压缩变形机制的影响,相变点以上固溶水淬处理后得到全β组织,使用Gleeble3800热模拟试验机和6.3MN锻造模拟试验机完成室温压缩。运用OM, XRD和TEM对不同应变后的组织进行观察,结果表明:应变速率为0.0005 s^-1,工程应变量为30%室温压缩真应力-真应变有明显的应变硬化阶段,应变速率为0.1 s^-1,工程应变量为30%室温压缩真应力-真应变曲线无明显的应变硬化阶段,而出现了流变软化现象;室温压缩真应力-真应变曲线均无双屈服现象,不同应变速率条件下,相同应变量的变形组织特征差异较小,室温压缩变形机制以滑移为主,随着应变量的增大,位错密度逐渐增大,出现了位错塞积、位错缠结和剪切;工程应变量为30%出现了应变诱发α"马氏体转变;应变速率为10 s^-1,工程应变量为50%和60%也出现了应变诱发α"马氏体转变。

Based on metastable β titanium alloy Ti-55531,the structure of the sample was obtained by solution quenching above the β phase.Room temperature compression was performed using a Gleeble3800 thermal simulation test machine and a 6.3 MN forging simulator.OM,XRD and TEM were used to observe the deformed structures after different strains.The results show that the maximum compression of 30% room temperature true-stress and true-strain curve at the strain rate of 0.0005 s^-1 is mainly divided into two stages that are elastic deformation stage and plastic deformation stage with obvious strain hardening stage.However,the maximum compression of 30% room temperature true-stress and true-strain curve at the strain rate of 0.1 s^-1 is mainly divided into two stages that are elastic deformation stage and plastic deformation stage with flow softening instead of obvious strain hardening.Both of them do not have double yield phenomenon.The deformation structures have few differences at different strain rates of the same reduction.The deformation mechanism is dominated by slip.With the strain increasing,the dislocation density increases gradually and the dislocation tangles and shears appear.Strain induced martensite transformation occurs at the compression of 30% and the strain rate of 0.0005 and 0.1 s^-1.Strain induced martensite transformation is also found at the strain rate of 10 s^-1 when the compression is 50% and 60%.