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为了提高高强厚钢板低温韧性,对550 MPa级厚钢板进行了730-910℃淬火和600℃回火的热处理,研究不同淬火温度对其组织及力学性能的影响.实验结果表明:在亚温区淬火后回火,随淬火温度升高,试样强度和韧性均表现为先降低后升高,淬火温度升高到完全奥氏体区,试样强度进一步升高,但韧性降低.760℃亚温淬火后回火,试样组织为粗大的多边形铁素体,大量呈长条状、针状M/A组元断续分布在铁素体基体和晶界上,严重恶化韧性,力学性能最差.相比完全奥氏体化淬火后回火,850℃亚温淬火后回火,试样具有最佳强韧配合,这是由于组织细化,铁素体的出现增加了大角晶界比例,以及存在大量均匀位错胞状亚结构和稳定薄膜状残余奥氏体引起的.
In order to improve the low temperature toughness of high strength steel plate, the 550 MPa grade steel plate was subjected to heat treatment of 730-910 ℃ and 600 ℃ tempering to study the effect of different quenching temperature on its microstructure and mechanical properties.The experimental results show that in the sub-temperature zone After quenching and tempering, with the increase of quenching temperature, the strength and toughness of the sample showed the first decrease and then the increase, the quenching temperature increased to the complete austenite region, the sample strength further increased, but the toughness decreased .760 ℃ Asia Temperatures after quenching and tempering, the sample was coarse polygonal ferrite, a large number of strip-shaped, acicular M / A component intermittently distributed in the ferrite matrix and grain boundaries, severe deterioration of toughness, the most mechanical properties Worse than the complete austenitizing quenching after tempering, 850 ℃ sub-tempered quenching after tempering, the sample has the best tough match, which is due to refinement of the organization, the emergence of ferrite increases the proportion of large-angle grain boundaries , As well as the existence of a large number of uniformly dislocated cellular sub-structures and stable film-like retained austenite.