含Nb微合金钢Q345和管线钢X70临界点的测定  

Determination of Critical Point of Nb-Microalloyed Steel Q345 and Pipeline Steel X70

作　　者：王生朝[1] 欧玲[1] 孙斌[1] 

机构地区：[1]湖南工业大学冶金工程学院,湖南株洲412007

出　　处：《湖南工业大学学报》2015年第5期88-91,共4页Journal of Hunan University of Technology

基　　金：湖南省科学技术厅科技计划基金资助项目(2014GK3169)

摘　　要：利用PCY热膨胀仪(热膨胀系数仪),以2℃/min的加热/冷却速率,测定了含Nb微合金钢Q345B,Q345C和管线钢X70的临界点温度Ac1,Ac3,Ar1和Ar3,并依据膨胀曲线图计算出它们的热膨胀系数。试验结果表明,对Q345B和Q345C进行加热时,它们的临界点Ac1和Ac3大致相同,分别相差8℃和3℃;而冷却时的临界点Ar1和Ar3,分别相差23℃和25℃。由于在X70钢中,含有更多的微合金元素Nb,V,Ti等,它们的碳氮化物的溶解和析出会对钢材的相变带来较大的影响,所以X70钢的各个临界点温度比Q345B和Q345C高出许多。但所测试的3个钢种的热膨胀系数没有太大的差别。The critical points of Ac1, Ac3, Ar3 and Ar1 of Nb-microalloyed steel Q345B, Q345C and pipeline steel X70 were studied by PCY thermal expansion instrument （thermal expansion coefficient apparatus） with 2℃ / min heating/cooling rate, and the thermal expansion coefficients were calculated according to the expansion curves of the experimental steel. The results showed that the difference values of critical points of Ac1 and Ac3 of Q345B and Q345C steel were not large in heating process, which were 8℃ and 3℃, but in cooling process the temperature differences of Ar1 and Ar3 were 20℃ and 25℃ respectively. As there was more microalloyed elements of Nb, V, Ti, etc. containing in X70, the dissolution and precipitation of carbon nitride brought about greater impact on the phase transformation of steel, the critical point of X70 is much higher than that of Q345B and Q345C. There is no much difference in the expansion coefficients of the three tested steel .

关 键 词：微合金钢 临界点 相变 热膨胀系数 

分 类 号：TG335.5[金属学及工艺—金属压力加工]