相变温度和奥氏体化温度对一种含Nb高碳钢相变动力学和组织的影响  

Effects of transformation temperature and austenitization temperature on the transformation kinetics and microstructure of a Nb microalloyed high-carbon steel

作　　者：周明星[1] 池亦骋 刘敬韬 李征乾 刘思华 张代琛 苏雪[1] 田俊羽 Zhou Mingxing;Chi Yicheng;Liu Jingtao;Li Zhengqian;Liu Sihua;Zhang Daichen;Su Xue;Tian Junyu(The State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China)

机构地区：[1]武汉科技大学耐火材料与冶金国家重点实验室,湖北武汉430081

出　　处：《钢铁钒钛》2024年第4期143-149,共7页Iron Steel Vanadium Titanium

基　　金：中信-CBMM铌钢研究与开发项目(2020-M836)。

摘　　要：为了优化一种含Nb高碳钢的热处理工艺,采用热膨胀法、OM、SEM、EBSD、硬度仪等研究了加热温度和相变温度对珠光体相变动力学和组织性能的影响。结果表明:升高加热温度将减慢珠光体相变动力学。原因:(1)奥氏体晶粒增大导致珠光体形核点数量降低;(2)奥氏体中固溶Nb含量增多,其对C扩散系数的减慢程度增强,从而降低珠光体长大速率。相变温度由625℃降低至575℃时,珠光体相变动力学同样减慢。此外,相变温度由625℃降低至575℃时,珠光体形核方式发生了变化,由主要在晶隅和晶棱处形核转变为主要在晶面和晶棱处形核。降低相变温度可以细化珠光体片层间距,提高珠光体钢的硬度,珠光体团簇尺寸同样随相变温度和加热温度的降低而显著细化。在试验所研究的三个工艺中,900℃加热+575℃相变工艺具有最高的硬度和最细的团簇尺寸。因此,为了获得最佳的强韧性匹配,建议降低加热温度和相变温度。In order to optimize the heat treatment process of a Nb microalloyed high-carbon steel,the effects of reheating temperature and transformation temperature on pearlite transformation kinetics and microstructure and properties were studied by dilatometry,optical microscope,scanning electron microscope,electron backscattering diffraction and hardness tests.The results show that the pearlite transformation kinetics is reduced by increasing the reheating temperature.One reason is that the number of pearlite nucleation sites decreases with the increase of prior austenite grain size.On the other hand,the solubility of Nb increases with the reheating temperature,which decreases the carbon diffusion coefficient and thus decreases the pearlite growth rate.The pearlite transformation kinetics decreases as the transformation temperature decreases from 625℃to 575℃.In addition,when the transformation temperature decreases from 625℃to 575℃,the pearlite nucleation mechanism changes from nucleation mainly at the corners and edges of prior austenite to nucleation mainly at the surfaces and edges.Moreover,the decrease in transformation temperature can refine the pearlite lamellar spacing and improve the hardness of the pearlitic steel.The pearlite nodule size is also significantly refined with the decrease of transformation temperature and reheating temperature.Among the three studied processes,900℃reheating with 575℃transformation technology provides the highest hardness and the smallest nodule size.Therefore,in order to obtain the best combination of strength and toughness,it is recommended to reduce the reheating temperature and transformation temperature.

关 键 词：高碳钢 珠光体 NB 加热温度 相变动力学 显微组织 

分 类 号：TF76[冶金工程—钢铁冶金] TG142[一般工业技术—材料科学与工程]