工程科学学报，第41卷，第8期：1037-1044,2019年8月 Chinese Joural of Engineering,Vol.41,No.8:1037-1044,August 2019 DOI:10.13374/j.issn2095-9389.2019.08.009;http://journals.ustb.edu.cn 石墨化碳素钢室温压缩过程中的不均匀变形行为 张永军四，张鹏程，张波，王九花，于文杰，韩静涛 北京科技大学材料科学与工程学院，北京100083 ☒通信作者，E-mail:zhangyj@(mater..usth.cdu.cn 摘要将0.46%含碳量（质量分数）的石墨化碳素钢在万能材料试验机上进行室温压缩变形，试验钢表现出良好的压缩变 形性能.根据载荷-位移曲线的变化特点，试验钢的压缩变形过程以位移7.0mm(对应相对压下量为58.3%)为节点分为两个 阶段：在位移≤7.0mm的压缩阶段，载荷呈线性增加，压缩试样的鼓度值逐渐增加而达到一个极大值(14.6%)，压缩试样中心 位置的维氏硬度增幅最大，为38.1HV,至位移7.0mm时试样端面径向伸长率的增幅为34%：而在位移>7.0mm的压缩阶段， 载荷呈指数增加，压缩试样的鼓度值从极大值开始逐渐减小，至位移为10.72mm时（相对压下量为89.3%），试样端面的径向 伸长率相比于位移7.0mm时增加了83.1%，压缩试样的中心位置的维氏硬度增幅最小，为32.7HV.上述试验数据表明，在位 移≤7.0mm的压缩过程中，压缩试样内的三个不均匀变形区的位置与传统压缩模型一致，但是当压缩变形进入位移>7.0mm 的压缩过程中，试样中心位置已不再是传统压缩模中变形程度最大的变形区了，即在这个阶段试样中的3个不均匀变形区的 变形程度发生了改变.正因这种不均匀变形区变形程度的改变导致了变形过程中载荷的急剧增加和鼓度值的减低.另外，在 压缩变形过程中，三个不均匀变形区中石墨粒子的微观变形量总是高于铁素体基体，其原因之一可以归结为石墨粒子中层与 层之间容易于滑动的结果. 关键词石墨化碳素钢：室温压缩变形：载荷-位移曲线：鼓度值：微观变形量 分类号TG142.1:TH142.1 Inhomogeneous deformation behavior in compressive deformation process at room temperature of graphitized carbon steel ZHANG Yong-jun,ZHANG Peng-cheng,ZHANG Bo,WANG Jiu-hua,YU Wen-jie,HAN Jing-tao School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China Corresponding author,E-mail:zhangyj@mater.ustb.edu.cn ABSTRACT Based on the development trends,graphitized carbon steel has been proposed as a low-sulfur and Pb-free free-cutting steel.This steel has attracted considerable attention because of its excellent cutting performance and good cold forging performance. This study investigates graphitized carbon steel containing 0.46%C with ferrite and graphite.In particular,its compression deforma- tion at room temperature was studied using a universal testing machine.The load-displacement curve was fitted,the drum shape and radial elongation of the end face of the compression specimens were calculated,the surface quality and microstructure of the compres- sion specimens were observed using optical microscopy and field-emission scanning electron microscopy,and the micro-deformation of graphite particles and the ferritic matrix in the compression specimens was statistically analyzed using Image-Pro 6.0.The results show that the tested steel exhibits good compression deformation performance.According to the varying characteristics of the load with respect to displacement,the compression deformation process of the tested steel is divided into two stages with a displacement of 7 mm (corre- sponding to 58.3%reduction):at the compression stage with displacement s7.0 mm,the load increases linearly with displacement. The value of the drum shape increases with increasing displacement,reaching a maximum value of 14.6%,the radial elongation of the 收稿日期：2018-08-01 基金项目：北京市自然科学基金资助项目(2172035)工程科学学报,第 41 卷,第 8 期:1037鄄鄄1044,2019 年 8 月 Chinese Journal of Engineering, Vol. 41, No. 8: 1037鄄鄄1044, August 2019 DOI: 10. 13374 / j. issn2095鄄鄄9389. 2019. 08. 009; http: / / journals. ustb. edu. cn 石墨化碳素钢室温压缩过程中的不均匀变形行为 张永军苣 , 张鹏程, 张 波, 王九花, 于文杰, 韩静涛 北京科技大学材料科学与工程学院, 北京 100083 苣通信作者, E鄄mail: zhangyj@ mater. ustb. edu. cn 摘 要 将 0郾 46% 含碳量(质量分数)的石墨化碳素钢在万能材料试验机上进行室温压缩变形,试验钢表现出良好的压缩变 形性能. 根据载荷鄄鄄位移曲线的变化特点,试验钢的压缩变形过程以位移 7郾 0 mm(对应相对压下量为 58郾 3% )为节点分为两个 阶段:在位移臆7郾 0 mm 的压缩阶段,载荷呈线性增加,压缩试样的鼓度值逐渐增加而达到一个极大值(14郾 6% ),压缩试样中心 位置的维氏硬度增幅最大,为38郾 1 HV,至位移7郾 0 mm 时试样端面径向伸长率的增幅为34% ;而在位移 > 7郾 0 mm 的压缩阶段, 载荷呈指数增加,压缩试样的鼓度值从极大值开始逐渐减小,至位移为 10郾 72 mm 时(相对压下量为 89郾 3% ),试样端面的径向 伸长率相比于位移7郾 0 mm 时增加了83郾 1% ,压缩试样的中心位置的维氏硬度增幅最小,为32郾 7 HV. 上述试验数据表明,在位 移臆7郾 0 mm 的压缩过程中,压缩试样内的三个不均匀变形区的位置与传统压缩模型一致,但是当压缩变形进入位移 > 7郾 0 mm 的压缩过程中,试样中心位置已不再是传统压缩模中变形程度最大的变形区了,即在这个阶段试样中的 3 个不均匀变形区的 变形程度发生了改变. 正因这种不均匀变形区变形程度的改变导致了变形过程中载荷的急剧增加和鼓度值的减低. 另外,在 压缩变形过程中,三个不均匀变形区中石墨粒子的微观变形量总是高于铁素体基体,其原因之一可以归结为石墨粒子中层与 层之间容易于滑动的结果. 关键词 石墨化碳素钢; 室温压缩变形; 载荷鄄鄄位移曲线; 鼓度值; 微观变形量 分类号 TG142郾 1; TH142郾 1 收稿日期: 2018鄄鄄08鄄鄄01 基金项目: 北京市自然科学基金资助项目(2172035) Inhomogeneous deformation behavior in compressive deformation process at room temperature of graphitized carbon steel ZHANG Yong鄄jun 苣 , ZHANG Peng鄄cheng, ZHANG Bo, WANG Jiu鄄hua, YU Wen鄄jie, HAN Jing鄄tao School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China 苣Corresponding author, E鄄mail: zhangyj@ mater. ustb. edu. cn ABSTRACT Based on the development trends, graphitized carbon steel has been proposed as a low鄄sulfur and Pb鄄free free鄄cutting steel. This steel has attracted considerable attention because of its excellent cutting performance and good cold forging performance. This study investigates graphitized carbon steel containing 0郾 46% C with ferrite and graphite. In particular, its compression deforma鄄 tion at room temperature was studied using a universal testing machine. The load鄄鄄 displacement curve was fitted, the drum shape and radial elongation of the end face of the compression specimens were calculated, the surface quality and microstructure of the compres鄄 sion specimens were observed using optical microscopy and field鄄emission scanning electron microscopy, and the micro鄄deformation of graphite particles and the ferritic matrix in the compression specimens was statistically analyzed using Image鄄Pro 6郾 0. The results show that the tested steel exhibits good compression deformation performance. According to the varying characteristics of the load with respect to displacement, the compression deformation process of the tested steel is divided into two stages with a displacement of 7 mm (corre鄄 sponding to 58郾 3% reduction): at the compression stage with displacement 臆7郾 0 mm, the load increases linearly with displacement. The value of the drum shape increases with increasing displacement, reaching a maximum value of 14郾 6% , the radial elongation of the