V和Ti元素对耐候钢过冷奥氏体连续冷却相变行为的影响研究

Investigation on the effects of V and Ti on continuous cooling transformation behaviour of weathering steel

进行了V、Ti元素含量不同的耐候钢的过冷奥氏体连续冷却转变热模拟试验并绘制了CCT曲线,研究了不同冷却速度以及V、Ti元素对耐候钢组织转变以及性能的影响。当V含量由0.03%提高至0.07%,马氏体转变开始温度Ms提高25℃,促进了马氏体相变。当Ti含量由0.03%提高至0.10%,扩大了贝氏体相变区、降低了贝氏体开始转变冷速,促进了贝氏体转变;同时,马氏体转变开始温度Ms降低22℃、马氏体转变终了温度Mf升高18℃,马氏体转变区域变窄,抑制了马氏体转变。随着冷却速率的提高,HV0.2硬度值逐渐增加。HV0.2硬度值主要受金相组织的尺寸和形貌影响,V、Ti的第二相析出物对HV0.2硬度值的影响不大。

Continuous cooling transformation thermal simulation experiment of weathering steel with various V or Ti contents was conducted, and effects of cooling rate and V or Ti element on microstructure transformation and property of weathering steel were investigated. When V content increases from0.03% to 0.07%, the martensite-start temperature increases 25 ℃, thereby promoting martensitic phase transformation. When Ti content increases from 0.03% to 0.10%, the bainitic phase transformation region expands, and the cooling rate with which bainite transformation starts decreases, thereby promoting bainitic phase transformation;meanwhile, martensite-start temperature decreases 22 ℃, and martensite-finish temperature increases 18 ℃, inducing martensitic phase transformation region shrinks,thereby restraining martensitic phase transformation. With the cooling rate increasing, HV0.2 hardness increases. HV0.2 hardness is mainly affected by the size and morphology of metallographic structure but fewer affected by second phase precipitates of V or Ti.