C5191磷青铜高应变速率条件下的拉伸性能和变形机制

Tensile Properties and Deformational Mechanism of C5191 Phosphor

摘要:

为了探讨C5191磷青铜在高应变速率条件下的动态响应,解决高速冲压工艺问题,本文利用电子万能试验机和分离式Hopkinson拉杆装置对C5191磷青铜分别进行应变速率为0.001S-1和500S-1、1000S-1、1500S-1的准静态和动态拉伸试验,结合SEM和TEM等手段,研究了C5191磷青铜的动态拉伸性能及其变形机制。结果表明：C5191磷青铜高应变速率动态拉伸与准静态条件相比较,其屈服强度和抗拉强度分别提升了32.77%和11.07%；应变硬化指数由0.075增加到0.251；材料强度应变速率敏感指数由0.005变化到0.022,呈现出明显的应变速率敏感性；高应变速率动态拉伸过程中,位错运动速度加快,导致位错“近程阻力”加大,使C5191磷青铜的变形抗力随着应变速率的增加而增大。可动位错数量的显著增多,多系滑移的开启,以及绝热温升软化效应一定程度上提高了C5191磷青铜高应变速率动态拉伸时的塑性。

Abstract:

To observe the dynamic mechanical response and investigate the processes of high speed stamping for C5191 phosphorus bronze, tensile properties and deformation behaviour of C5191 phosphor bronze under quasi-static tensile condition at a strain rate of 0.001 s_-1 by electronic universal testing machine, and dynamic tensile condition at strain rate of 500, 1000 and 1500 s_-1 by split Hopkinson tensile bar (SHTB) apparatus were studied. The effects of strain rate and the mechanism were investigated by means of SEM and TEM. The results showed that the yield strength and tensile strength of C5191 phosphor bronze under high strain rates deformation increased by 32.77% and 32.77% respectively compared with quasi-static condition, the strain hardeningSindexSincreases from 0.075 toS0.251, andSthe strength of the materialSstrain rateSsensitivity indexSchange from 0.005 toS0.022, which presented a clear sensitive to strain rates. The deformation resistance increased with increasing the strain rate due to the stronger short range resistance induced by the acceleration of dislocation motion. The ability of plastic deformation of C5191 phosphor bronze increased due to the number of movable dislocations increased significantly, started multi-line slip, and the soft effect of adiabatic temperature rise at the strain rate ranging from 500 to 1500 s_-1.