【摘要】 为解决40CrNiMo钢在保持其良好淬透性的同时添加镍所带来的高成本问题，提出了通过钒(V)微合金化降低镍含量的技术方案，旨在保持优异淬透性的同时实现成本控制。采用扫描电镜(SEM)和透射电镜(TEM)等对试验钢的原奥氏体晶粒和微观组织进行表征，通过连续冷却转变(CCT)曲线测定和端淬试验分析了所开发的40CrNiMoV钢与40CrNiMo钢的淬透性差异，并探讨镍替代原理。结果表明：V微合金化降低了40CrNiMo钢获得全马氏体组织的临界冷却速度，当冷速为10℃/s时，40CrNiMoV钢组织为全马氏体，而40CrNiMo钢中仍存在部分贝氏体；V对淬透性的改善与奥氏体化温度有关，在850℃奥氏体化时，未溶MC型碳化物的存在及晶粒细化导致合金元素固溶量不足，淬透性提升有限；而奥氏体化温度为870和900℃时，40CrNiMoV钢组织中碳化物完全溶解且晶粒适度粗化，表现出了更好淬透性；定量分析表明，870℃奥氏体化时，质量分数为0.08%的V元素对理想临界直径(D_I)的增益效果达1.2%Ni(两钢Ni含量差值)的0.99倍，表现出优秀的淬透性改善效果。更多还原

【Abstract】 To address the high cost issue of adding nickel to 40CrNiMo steel while maintaining its good hardenability, a technical solution was proposed to reduce nickel content through vanadium(V) microalloying, aiming to achieve cost control while maintaining excellent hardenability. The original austenite grains and microstructure of the experimental steels were characterized using scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The difference in hardenability between the developed 40CrNiMoV steel and 40CrNiMo steel was analyzed by continuous cooling transformation(CCT) curve measurement and end-quenching test, and the principle of nickel substitution was explored. The results show that V microalloying reduces the critical cooling rate for obtaining a fully martensitic structure in the 40CrNiMo steel. When the cooling rate is 10 ℃/s, the microstructure of the 40CrNiMoV steel is fully martensite, while some bainite still exists in the 40CrNiMo steel. The improvement of hardenability by V is related to the austenitizing temperature. When the austenitizing temperature is 850 ℃, the presence of undissolved MC type carbides and grain refinement restrict solid solution of alloy elements, resulting in limited improvement of hardenability. When the austenitizing temperature is 870 ℃ and 900 ℃, the carbides in the microstructure of the 40CrNiMoV steel completely dissolve and the grains undergo moderate coarsening, exhibiting better hardenability. Quantitative analysis shows that when austenitized at 870 ℃, the enhancement effect of 0.08% V element on the ideal critical diameter(D_I) is 0.99 times that of 1.2% Ni(the difference in Ni content between the two steels), demonstrating excellent improvement in hardenability.更多还原