The present study aims to investigate the evolution of microstructure of 304 austenitic stainless steel (SS) due to reversion annealing of cold deformed samples under different schedules. Evolution of phases in selected samples was identified and quantified by X-ray diffraction analysis along with corresponding microstructural characterisation through optical, scanning and transmission electron microscopy. Mechanical properties of the samples were determined by carrying out tensile test. Electron microscopy of selected samples has revealed that, while strain induced martensite, deformation twins, ε-martensite and high dislocated structures are the dominant microstructural features of the cold deformed samples, reversion annealing of the same results into ultrafine-grained reverted austenite, cell type dislocation sub-structures with some amount of untransformed martensite. The maximum tensile strength of 1589 MPa with an elongation of 9% has been obtained after 20% deformation at −196 °C (20LND), whereas 40% deformation at 0 °C (40ZCD) results into a tensile strength of 1225 MPa with 13% elongation. Annealing of 40ZCD and 20LND specimens at 300 °C results in significant improvement in tensile strength, while annealing at 725 °C increases the elongation with a decrease in tensile strength. During reversion annealing, strain induced martensite transforms to austenite through shear and diffusional processes. However, the reversion is essentially diffusional in nature at a higher temperature.

本研究的目的是研究在不同的时间表下由于冷变形样品的反向退火而导致的304奥氏体不锈钢（SS）的微观组织的演变。通过X射线衍射分析以及通过光学，扫描和透射电子显微镜进行的相应微结构表征，鉴定并量化了所选样品中相的演变。通过进行拉伸试验来确定样品的机械性能。选定样品的电子显微镜显示，虽然应变诱发的马氏体，变形孪晶，ε-马氏体和高位错结构是冷变形样品的主要显微组织特征，但相同结果的回复退火为超细晶粒还原奥氏体，单元类型的位错亚结构，具有一定数量的未转变的马氏体。在-196°C（20LND）下变形20％之后，获得了最大拉伸强度为1589 MPa，伸长率为9％，而在0°C（40ZCD）下变形了40％，则拉伸强度为1225 MPa。伸长率％。40ZCD和20LND样品在300°C下退火可显着提高抗张强度，而在725°C下退火可提高伸长率，而抗张强度却降低。在回复退火过程中，应变诱发的马氏体通过剪切和扩散过程转变为奥氏体。然而，该回复本质上在较高温度下本质上是扩散的。在-196°C（20LND）下20％变形后，获得了最大拉伸强度为1589 MPa，伸长率为9％，而在0°C（40ZCD）下40％变形得到的拉伸强度为1225 MPa（13）伸长率％。40ZCD和20LND样品在300°C下退火可显着提高抗张强度，而在725°C下退火可提高伸长率，而抗张强度却降低。在回复退火过程中，应变诱发的马氏体通过剪切和扩散过程转变为奥氏体。然而，回复本质上在较高温度下本质上是扩散的。在-196°C（20LND）下变形20％之后，获得了最大拉伸强度为1589 MPa，伸长率为9％，而在0°C（40ZCD）下变形了40％，则拉伸强度为1225 MPa。伸长率％。40ZCD和20LND样品在300°C下退火可显着提高抗张强度，而在725°C下退火可提高伸长率，而抗张强度却降低。在回复退火过程中，应变诱发的马氏体通过剪切和扩散过程转变为奥氏体。然而，该回复本质上在较高温度下本质上是扩散的。而在725°C的退火温度下，伸长率增加，抗拉强度降低。在回复退火过程中，应变诱发的马氏体通过剪切和扩散过程转变为奥氏体。然而，该回复本质上在较高温度下本质上是扩散的。而在725°C的退火温度下，伸长率增加，抗拉强度降低。在回复退火过程中，应变诱发的马氏体通过剪切和扩散过程转变为奥氏体。然而，该回复本质上在较高温度下本质上是扩散的。