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采用SEM和TEM分析了等通道挤压奥氏体不锈钢中孪晶的细化过程。结果表明,一道次变形后,原退火孪晶受剪切断裂,并在一些区域形成小的形变孪晶;随着挤压道次增加,孪晶通过孪生和滑移的方式进一步变形,滑移由晶界开始并向晶粒内部扩展,最后将大的孪晶破碎,在孪晶层状结构内部通过孪生方式形成二次孪晶,在随后的变形过程中,逐渐形成微米级孪晶组织。八道次挤压后形成纳米级的晶粒和细小的微孪晶组织。
SEM and TEM were used to analyze the thinning process of twin in austenitic stainless steel. The results show that after a single deformation, the primary annealed twin undergoes shear fracture and forms small deformation twins in some areas. As the extrusion pass increases, the twin strands further deform through twinning and slippage, sliding Starting from the grain boundaries and expanding into the grains, the large twins are finally crushed to form secondary twins through twinning in the twinned layered structure. Micrometric twins are gradually formed during the subsequent deformation. After eight times the formation of nano-scale grains and micro-twinned microstructure.