摘要
使用Gleeble热模拟机研究了V-N和V-N-Nb微合金钢的高温热塑性,利用SEM和金相显微镜对热拉伸试样断口形貌和组织进行分析,并通过TEM对析出相进行了表征。结果表明在V-N钢基础上添加质量分数为0.024%的Nb,总体上降低了在第Ⅲ脆性温度区(950~600℃)的热塑性,使塑性低谷区变宽、变深。断面收缩率Z值低于40%的临界温度区间,V-N钢为862~713℃,而V-N-Nb钢在903~700℃以下,塑性低谷区宽度增加了54℃以上。2种钢的Z最低值在750℃,V-N钢为24.5%,V-N-Nb钢为15.5%。A_(3)温度以上,V-N-Nb钢中更多细小的碳氮化物析出是它热塑性低于V-N钢主要原因;A_(3)温度以下,750℃时Z最低值是由薄膜铁素体和碳氮化物析出综合作用的结果,温度降至700℃时Z提高,较厚的晶界铁素体和晶内铁素体生成是Z升高的主要原因。
The hot ductility of V-N and V-N-Nb microalloyed steels was studied by using Gleeble thermal simulator. The fracture morphology and microstructure of hot tensile specimens of V-N and V-N-Nb microalloyed steels were analyzed by SEM and metallographic microscope, and the precipitates were characterized by TEM. The results show that the addition of 0.024%Nb to V-N steel reduces the hot ductility in the third brittle temperature zone(950-600 ℃), and makes the plastic trough zone wider and deeper. The critical temperature range of reduction of area(Z) below 40% for V-N steel is 862-713 ℃, and 903 ℃ to below 700 ℃ for V-N-Nb steel. The width of plastic trough zone for V-N-Nb steel is increased by more than 54 ℃. The lowest Z value occurs at 750 ℃ for both steels, which is 24.5% for V-N steel and 15.5% for V-N-Nb steel, respecitively. The main reason for lower hot ductility of V-N-Nb steel than V-N steel is that more and finer microalloy carbonitrides are precipitated in V-N-Nb steel, when the temperature is higher than A_(3). The lowest Z value at 750 ℃ below A_(3) temperature is the result of the synthesis of thin film ferrite and carbonitride precipitation, while the formation of thicker grain boundary ferrite and intragranular ferrite increases Z value when the temperature drops to 700 ℃.
作者
马壮
侯振伟
陈雪慧
连小金
刘静
MA Zhuang;HOU Zhenwei;CHEN Xuehui;LIAN Xiaojin;LIU Jing(State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China;Department of Structural Steels,Central Iron and Steel Research Institute,Beijing 100081,China;Suqian Jinxin Steel Rolling Co.,Ltd.,Suqian 223800,Jiangsu,China)
出处
《钢铁研究学报》
CAS
CSCD
北大核心
2022年第10期1177-1186,共10页
Journal of Iron and Steel Research
