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采用连续式氮气保护热处理炉和实验室箱式热处理炉,研究了正火以及正火后加速冷却+回火工艺对电熔化焊管用C-Mn钢显微组织和抗氢致开裂(HIC)性能的影响。结果表明:试验钢采用正火虽然可以细化晶粒,但无法消除因连铸坯枝晶偏析造成的钢板带状组织,带状组织对试验钢的抗HIC性能有显著的劣化作用;采用正火后加速冷却工艺,带状组织完全消除,形成了铁素体和贝氏体的混合组织,板条状的贝氏体在原奥氏体晶内形核,有效地分割了原奥氏体晶粒,再通过后续合适的回火热处理,形成了热力学稳定的细晶组织,使得钢的抗HIC性能明显改善。
The continuous nitrogen protection heat treatment furnace and the laboratory box heat treatment furnace were used to study the microstructure and hydrogen cracking resistance (HIC) performance of C-Mn steel for electric fusion pipe by normalizing and post-normalizing accelerated cooling + tempering process Impact. The results show that although the normalized steel can refine the grain, it can not eliminate the strip-like structure and the banded structure of the steel strip caused by dendritic segregation of the continuous casting slab, which can significantly degrade the HIC resistance of the test steel. After the fire accelerated cooling process, the band structure completely eliminated, forming a mixed structure of ferrite and bainite, lath bainite nucleation in the original austenite, the effective division of the original austenite Grain, and then through the appropriate subsequent tempering heat treatment, the formation of a thermodynamically stable fine grain structure, making the steel HIC performance improved significantly.