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利用光学金相、电子金相、膨胀、磁性、X射线衍射、硬度等方法研究了18Cr_2Ni_4WA钢在连续冷却时粒状贝氏体的形成条件、组织形态及其影响因素,和回火转变的特点。结果表明,BF基体有二种形态-块状和条状。慢冷时为块状,快冷和提高奥氏体化温度有利于形成条状。M-A岛的随机分布和定向分布与此相对应。碳富集程度不同导致M-A岛的结构不同-碳偏低的、大而不规整的多为M岛,碳偏高的、小而规整的多为A岛。奥氏体成分的均匀化和冷却速度是影响粒贝组织形态和机械性能的二个最主要的因素,奥氏体成分的充分均匀化及随后快冷有利于粒贝组织和性能的改善。BF基体的回火抗力高于M-A中M的回火抗力。二次高温回火能有效地消除二次淬火M岛的脆化作用。与一次回火相比能显著改善强韧性、组织稳定性和软化效果。
The formation conditions, microstructure and influencing factors of the granular bainite and the characteristics of the tempering transformation of 18Cr_2Ni_4WA steel during continuous cooling were studied by means of optical metallography, electronic metallography, swelling, magnetism, X-ray diffraction and hardness test. The results show that there are two kinds of BF matrix - block and strip. Slow cooling when the block, rapid cooling and increase the austenitizing temperature is conducive to the formation of bar. M-A island random distribution and directional distribution corresponding to this. Different carbon enrichment leads to different structures of M-A islands - M is low in carbon, M isles in large irregularity, and carbon in high and small but regular A islands. The homogenization and cooling rate of austenite are the two most important factors that affect the morphology and mechanical properties of shellfish. The uniform homogenization of austenite and subsequent rapid cooling are good for the improvement of shell structure and properties. The tempering resistance of the BF substrate is higher than the tempering resistance of M in M-A. Secondary high temperature tempering can effectively eliminate the secondary quench island M embrittlement. Compared with a tempering can significantly improve the strength and toughness, tissue stability and softening effect.