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采用完全淬火+两相区淬火+临界区淬火的三步热处理方式,利用SEM、EBSD、XRD、TEM和EPMA等手段研究了0.12C-3.0Mn低碳中锰钢组织演变规律和力学性能,并对0.12C-3.0Mn钢进行了-40~-196℃的系统低温冲击实验研究。结果表明,三步热处理后0.12C-3.0Mn钢的组织为临界铁素体、马氏体/贝氏体和残余奥氏体,残余奥氏体呈块状和条状分布在原奥氏体晶界上和马氏体/贝氏体板条界上,残余奥氏体主要通过临界淬火富集C和Mn元素达到稳定,室温下稳定的残余奥氏体含量最高可达到15%。由于残余奥氏体的应变诱导塑性(TRIP)效应,0.12C-3.0Mn钢具有良好的塑性和优异的低温韧性:断后总延伸率高于30%,均匀延伸率高于16%,-80℃下冲击功可达到200 J。
The microstructure evolution and mechanical properties of 0.12C-3.0Mn low carbon medium manganese steel were studied by means of SEM, EBSD, XRD, TEM and EPMA with three-step heat treatment method of complete quenching + two-phase quenching + critical quenching The 0.12C-3.0Mn steel was -40 ~ -196 ℃ system low temperature impact experimental study. The results show that the microstructures of 0.12C-3.0Mn steel after three-step heat treatment are critical ferrite, martensite / bainite and retained austenite. The residual austenite is massive and strip-like distributed in the original austenite Boundary and martensite / bainite slab boundaries, the residual austenite is mainly enriched by critical quenching of C and Mn elements to stabilize the room temperature stable retained austenite content up to 15%. Due to the strain-induced plasticity (TRIP) effect of retained austenite, 0.12C-3.0Mn steel has good ductility and excellent low temperature toughness: the total elongation at break is higher than 30% and the uniform elongation is higher than 16% at -80 ℃ Under impact energy can reach 200J.