低碳中锰Q690F高强韧中厚板生产技术

对低碳中锰Q690F高强韧中厚板进行了控扎控冷和热处理工艺试验，观察了显微组织，测定了拉伸和冲击性能，并阐述了其强韧化机制.结果表明:中锰钢的显微组织为亚微米尺度的回火马氏体+逆转变奥氏体的复合层状组织.中锰中厚板1/4厚度位置的屈服强度、抗拉强度、延伸率、-60℃冲击功分别为725MPa，840MPa，27.7%，130J.逆转变奥氏体发生相变诱导塑性(TRIP)效应产生的应变硬化是中锰钢主要的强化机制;TRIP效应吸收大量的应变能，推迟颈缩，增加均匀延伸率，是中锰钢主要的增塑机制;TRIP效应有效地提高了裂纹形成功和裂纹扩展功，是中锰钢主要的韧化机制.

Production Technology of Low-C Medium-Mn Q690F High Strength and Toughness Mid-Thick Steel Plate

The thermomechanical control process(TMCP) and heat treatment test were conducted on low-C medium-Mn Q690F high strength and toughness mid-thick steel plate. The microstructure of the tested steel was analyzed and the tensile and impact properties were measured. The strengthening and toughening mechanisms were discussed. The results showed that the microstructure of the tested steel is a layered structure composed by sub-micrometer tempered martensite and reverse transformation austenite.The yield strength， tensile strength，elongation， and-60℃ impact energy of the tested plate at 1/4 thickness are 725MPa， 840MPa， 27.7%， 130J， respectively. The strain hardening caused by transformation induced plasticity(TRIP)from the reversed austenite is the main strengthening mechanism. The TRIP effect which absorbs a large amount of strain energy， delays the necking and increases the uniform elongation is considered as the main mechanism for plasticizing. Furthermore， the TRIP effect can increase the energy of the crack initiation and propagation effectively， it is also regraded as the main toughening mechanism.