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320 mm厚度连铸坯采用控轧-控冷轧制成100 mm钢板,通过淬火-回火热处理制备690 MPa级特厚超高强海工钢,研究了表面和1/4厚度处的回火马氏体对系列低温冲击性能的影响。结果表明:特厚钢板表面奥氏体晶粒均匀细小,回火后获得几乎为全回火马氏体组织,其低温冲击韧性比较低。淬火过程中,过快的冷却速度提高了钢板表面马氏体转变的过冷度,引起马氏体转变的形核率降低,导致特厚板表面马氏体板条束、板条块等亚结构的相对粗大,造成冲击韧性低下,尤其降低-60℃和-80℃低温冲击韧性。
The 320 mm thick slab was rolled by controlled rolling-controlled cold rolling into 100 mm steel plates. The 690 MPa-class extra-thick super-high strength marine steel was prepared by quenching-tempering heat treatment. The effects of tempering on the surface and at ¼ thickness The Effect of Martensite on Series Low Temperature Impact Properties. The results show that the austenite grains on the surface of ultra-thick steel plate are uniform and fine, and almost tempered martensite is obtained after tempering. The impact toughness at low temperature is relatively low. Quenching process, the cooling rate is too fast to improve the martensitic transformation of the steel surface supercooling, causing the martensitic transformation of the nucleation rate decreased, resulting in super-thick plate surface martensite lath, lath block Asia Relatively large structure, resulting in low impact toughness, in particular, to reduce -60 ℃ and -80 ℃ low temperature impact toughness.