超级贝氏体组织中的应力诱发相变研究

Stress-induced phase transformation of super bainite microstructure

为了研究钢中超级贝氏体产生应力诱发相变对其组织和力学性能的影响,将60Mn2SiCr钢经完全奥氏体化后,在250℃~270℃盐浴炉中等温处理获得超级贝氏体,并通过在疲劳试验机上施加不同的拉-拉交变载荷来探讨其对实验钢力学性能的影响。使用SEM、TEM和XRD对样品分别进行组织形貌观察和相组成的确定。显微组织中部分残余奥氏体发生应力诱发相变,转变为孪晶马氏体,致使钢的强塑积提高近32.4%。结果表明:超级贝氏体中的部分残余奥氏体能够通过产生应力诱发相变改善钢的强韧性。

The effect of stress-induced transformation of super bainite on its structure and mechanical properties in steel was investigated.A typical super bainite microstructure was obtained in experimental steel 60Mn2SiCr through a full austenitization process and subsequent isothermal treatment at250 ℃~270 ℃ in a salt bath furnace.The effect of super bainite on the mechanical properties of experimental steel was discussed by applying different tension-tension alternating loads with a fatigue-testing machine.The microstructural morphology of the sample was observed,and the phase composition of the sample was ascertained through SEM,TEM,and XRD analysis.A portion of the residual austenite in the microstructure was transformed into twin martensite through stress-induced transformation under loading.Tensile strength and ductility increased by nearly 32.4%.Results showed that austenite retained in the super bainite can improve steel toughness by generating stress-induced phase transformation.