Nb对高碳钢珠光体球化的影响  

Effect of Nb on spheroidization of pearlitic for high carbon steel

作　　者：冯路路 吴开明[1] 乔文玮 谢兴 张国宏[5] FENG Lu-lu;WU Kai-ming;QIAO Wen-wei;XIE Xing;ZHANG Guo-hong(The State Key Laboratory of Refractories and Metallurgy,Collaborative Innovation Center for Advanced Steels,International Research Institute for Steel Technology,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China;School of Mechanical Engineering,Jing Chu University of Technology,Jingmen 448000,Hubei,China;Jiangsu Huaneng Cable Co.,Ltd.,Gaoyou 225613,Jiangsu,China;Wuhan Second Ship Design and Research Institute,Wuhan 430064,Hubei,China;Analytical and Testing Centre,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China)

机构地区：[1]武汉科技大学省部共建耐火材料与冶金国家重点实验室,高性能钢铁材料及其应用省部共建协同创新中心,国际钢铁研究院,湖北武汉430081 [2]荆楚理工学院机械工程学院,湖北荆门448000 [3]江苏华能电缆股份有限公司,江苏高邮225613 [4]中国船舶重工集团公司第七一九研究所,湖北武汉430064 [5]武汉科技大学分析测试中心,湖北武汉430081

出　　处：《钢铁研究学报》2020年第8期734-739,共6页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(U1532268,51671149);荆楚理工学院校级科研项目(PY202004);武汉科技大学重大项目(2018TDX07);国家外专局高等学校学科创新引智111计划资助项目(2019BJH026)。

摘　　要：设计了2种不同Nb含量的高碳珠光体钢(0.025Nb和Free-Nb),采用光学显微镜、扫描显微镜、透射电镜和硬度测试仪对两种试验钢珠光体球化前后的显微组织进行了观察和球化后的硬度进行了测量。结果表明:Nb元素可以细化高碳珠光体钢的片层间距,相同条件下具有更多的铁素体-渗碳体界面,在球化退火的第一阶段提供大量的位错和亚晶界使片状珠光体快速熔断,同时也给第二阶段碳的扩散提供高速扩散通道;细小的片层间距缩短了碳和合金元素的扩散距离,使球化转变速度加快,促进了高碳珠光体的球化。Nb元素的添加获得了细小片层间距以及更多的合金碳化物使试验钢的初始硬度偏高,球化退火前4 h硬度值下降幅度较大,球化退火4 h后对试验钢硬度的影响不大。Two kinds of high-carbon pearlitic steel(0.025 Nb and free-Nb)with different Nb contents were designed.The microstructures of the pearlite before and after spheroidization were observed by optical microscope,scanning microscope,transmission electron microscope and the hardness of test steel after spheroidization was measured by hardness tester.The results show that Nb can refine the interlamellar spacing of high-carbon pearlitic steel,and have more ferrite-cementite interfaces under the same conditions.In the first stage of spheroidal annealing,a large number of dislocations and sub-boundaries are provided to make the lamellat pearlite broken-up rapidly,and meanwhile,high-speed diffusion channel is provided for the carbon diffusion in the second stage of spheroidal annealing.The fine interlamellar spacing shortens the diffusion distance of carbon and alloy elements,the spheroidization transformation of pearlite was accelerated by the separation.With the addition of Nb element,the initial hardness of the test steel was relatively high due to the fine interlamellar spacing and more alloy carbide.Nb microalloying makes the hardness of test steel decrease rapidly 4 hours before spheroidizing annealing,but has little effect on hardness after 4 hours.

关 键 词：NB 高碳珠光体钢 球化退火 片层间距 位错 亚晶界 

分 类 号：TG142.1[一般工业技术—材料科学与工程]