等径角挤压道次对纯锡显微组织与力学性能的影响

Effect of Equal Channel Angular Pressing Pass on Microstructure and Mechanical Properties of Pure Tin

在室温下对纯度为99.99%的锻态纯锡板进行不同道次(0~20道次)的等径角挤压(ECAP),研究ECAP道次对纯锡显微组织和力学性能的影响。结果表明:在ECAP的剧烈剪切作用下纯锡晶粒中产生孪晶,并发生孪晶诱导再结晶,晶粒显著细化,当ECAP道次超过12道次时,晶粒细化效果减弱;随着ECAP道次的增加,纯锡的织构强度和最大取向密度降低,硬度、强度和断后伸长率均增大;与锻态纯锡相比,经20道次ECAP后的硬度、屈服强度、抗拉强度和断后伸长率分别提高了9.09%,5.14%,32.08%,144.19%;当ECAP道次数少于8道次时,纯锡的主要强化机制为加工硬化,而当ECAP道次数多于8道次时,主要强化机制为细晶强化。

The forged pure tin plate with purity of 99.99%was treated by equal channel angular pressing(ECAP)for different passes(0-20 passes)at room temperature.The effect of ECAP pass on the microstructure and mechanical properties of the pure tin was studied.The results show that under the severe shear of ECAP,twinning and twin-induced recrystallization occurred in pure tin grains,and the grains were significantly refined.After ECAP for more than 12 passes,the grain refinement effect was weakened.With increasing ECAP pass,the texture strength and maximum orientation density of the pure tin decreased,while the hardness,strength and percentage elongation after fracture increased.Compared with those of the forged pure tin,the hardness,yield strength,tensile strength and percentage elongation after fracture after 20 passes of ECAP increased by 9.09%,5.14%,32.08%and 144.19%,respectively.The main strengthening mechanism of the pure tin was work hardening with ECAP pass of less than 8,and was fine grain strengthening with ECAP pass of more than 8.