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研究了不同回火温度和循环回火次数对40Cr Ni2Si2Mo VA(300M)超高强度钢的显微组织和性能的影响。结果表明,300M钢经860℃油淬,在250~400℃回火后,材料内部显微组织均由板条马氏体、下贝氏体和少量的奥氏体组成,但在回火温度升高的过程中,材料内部的板条状马氏体的宽度逐渐增大,下贝氏体的含量也在增多。相比之下,当回火温度为300℃,循环回火次数为2次时,硬度最低,塑性和韧性达到一个最佳匹配,使得该材料具有最佳强韧化特性。
The effects of different tempering temperatures and cycles on the microstructure and properties of 40Cr Ni2Si2Mo VA (300M) ultra-high strength steel were studied. The results show that the microstructure of 300M steel is quenched at 860 ℃ and tempered at 250-400 ℃. The microstructure of the material consists of lath martensite, lower bainite and a small amount of austenite. However, In the process of raising, the width of lath martensite in the material gradually increases and the content of lower bainite also increases. In contrast, when the tempering temperature of 300 ℃, the number of cycles of tempering 2 times, the lowest hardness, plasticity and toughness to achieve a best match, making the material has the best toughening properties.