对比新型淬火-分配-回火(Q-P-T)和传统淬火-回火(Q-T)处理对中、低碳钢力学性能的影响发现, 在提高材料的强塑积方面 Q-P-T处理远胜于Q--T处理, 特别是对中碳钢的效果更为显著. 在所研究的试样中, Fe-0.42C-1.46Mn-1.58Si-0.028Nb合金的强塑积经Q-P-T处理后高达31627 MPa?%, 且延伸率达20.3%, 不仅远高于传统Q-T处理的试样, 而且已满足新一代先进高强度钢预测的性能. 显微组织分析表明, Q-T和Q-P-T处理的差异在于残留奥氏体的量和尺寸分布以及马氏体板条的均匀程度. 前者含少量 (<3%) 较薄的“薄膜状”残留奥氏体, 且马氏体板条尺寸范围较宽; 而后者含较多较厚的“薄片状”残留奥氏体, 且马氏体板条尺寸分布较窄. 因此Q-P-T处理的先进高强度钢具有承受较强的塑性变形和阻止微裂纹扩展的能力.
Compared with traditional quenching and tempering (Q-T) treatment, the product of strength and elongation of the carbon steel can be enhanced significantly by novel quenching-partitioning-tempering (Q-P-T) treatment, especially for the medium carbon steel. Based on the tensile results, the product of strength and elongation of the Fe-0.42C-1.46Mn-1.58Si-0.028Nb specimen treated by Q-P-T, is up to 31627 MPa?% with elongation 20.3\%, which not only is higher than the specimen treated by Q-T process, but also meets the mechanical properties predicted of next generation advanced high strength steel. Microstructural analysis indicates the differences in Q-T and Q-P-T process lie on the amount of retained austenite and its size distribution as well as the size range of lath martensite. The former results in the low amount (<3%) of thin film-like austenite in addition to nonuniform martensite size, while the later results in the high amount of thick flake-like austenite accompanying uniform martensite size. Therefore, the higher barrier for micro-crack propagation and the better plastic deformation ability of advanced high strength steel (AHSS) can be obtained by Q-P-T treatment.
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