钒微合金化低碳贝氏体钢的连续冷却相变特性

Phase Transformation Characteristics of Vanadium Microalloying Low Carbon Bainitic Steel in Continuous Cooling Process

采用热膨胀法测定6种不同成分低碳贝氏体钢的连续冷却转变(CCT)曲线。CCT曲线表明,加入微量硼能使含钒低碳贝氏体钢在大于0.3℃/s的冷速下获得贝氏体组织,而V-N微合金化的低碳贝氏体获得全贝氏体的临界冷速要高于V-B钢,且贝氏体转变的开始温度也要较V-B钢高20℃左右。在含钒、氮低碳贝氏体钢中加入钼、铬将会促进钢的贝氏体相变,但钼的作用要优于铬;钼、铬的加入可使含钒、氮低碳贝氏体钢的贝氏体转变温度降低至少30℃,且贝氏体组织得到了细化,钢的维氏硬度也提高了HV 10～30。

The continuous cooling transformation（CCT） curves of experimental steels were tested with heat dilatometer.The results show that the low carbon steel containing V and B can obtain fully bainitic microstructures more than 0.3℃/s of cooling rate.Compared to V-B steel,low carbon steels microalloying with V-N have higher critical cooling rate to achieve fully bainite,also bainite start temperature is about 20℃ higher than V-B steel.The element of Mo and Cr additions to V-N microalloyed low carbon steels can promote bainite transformation and Mo is more effective than Cr.Adding Mo and Cr into V-N microalloyed low carbon bainitic steels can lower bainite transformation temperature at least 30℃ and refine bainitic microstructures,thus increase the Vickers hardenss HV10-30.