46MnVS6非调质钢的过冷奥氏体连续冷却相变

Continuous Cooling Transformation of Supercooled Austenite of 46MnVS6 Non-quenched and Tempered Steel

采用淬火膨胀仪、光学显微镜、维氏硬度计等研究了完全奥氏体化46MnVS6非调质钢经不同冷却速率冷却至室温后的显微组织和显微硬度,测定了其过冷奥氏体连续冷却转变(CCT)曲线,探讨了合金元素及冷却速率对过冷奥氏体连续冷却相变的影响。结果表明:46MnVS6钢的CCT曲线可分为高温转变区域、中温转变区域和低温转变区域,且中、低温转变区域互相分离;当冷却速率小于2℃·s^(-1)时,组织主要为铁素体和珠光体,随着冷却速率的增大,铁素体和珠光体含量减少,平均晶粒尺寸减小,马氏体含量增加,当冷却速率大于5℃·s^(-1)时,组织主要为马氏体;随着冷却速率从0.5℃·s^(-1)增大至60℃·s^(-1),46MnVS6钢的显微硬度由285HV1增至683HV1。

The microstructure and micro-hardness of complete austenitization 46MnVS6 non-quenched and tempered steel were analyzed after cooling to room temperature at different cooling rates by using thermal dilatometer, optical microscope and Vickers hardness tester. The continuous cooling transformation （CCT） curves of supercooled austenite were tested. The influence of alloying element and cooling rate on the continuous cooling transformation of supercooled austenite was discussed. The results show that the CCT curve could be divided into high temperature transition region, middle temperature transition region and low termperature transition region, and the middle temperature transition region and low temperature transition region were separated. The microstructure was mainly ferrite and pearlite when the cooling rate was below 2 ℃ s-1. With the increase of cooling rate, the content and average grain size of ferrite and pearlite decreased, and the content of martensite increased. The main mierostructure was martensite when the cooling rate was over 5℃ s-1. With the increase of cooling rate from 0.5 ℃ s-1 to 60 ℃ s-1 , the micro-hardness of 46MnVN6 steel increased from 285 HV1 to 683 HV1.