Influence of sulfide modification on inclusions and cutting properties of 20MnCr5 gear steel
YU Wen-chao1, ZHANG Xiao-lu1, JIN Guo-zhong2, HU Fang-zhong2, HE Xiao-fei1
1. Research Institute of Special Steels, Central Iron and Steel Research Institute, Beijing 100081, China; 2. Technology Center, Ma'anshan Iron and Steel Co., Ltd., Ma'anshan 243003, Anhui, China
Abstract:Gear steel is widely used in automobile, machinery and other drive systems. Free cutting is one of the main ways to improve gear processing efficiency and reduce manufacturing cost. Increasing sulfur content in steel is an effective way to improve the cutting performance of gear steel. However, excessive sulfur will form strip MnS during rolling, which will increase the anisotropy of steel. Therefore, it is necessary to modify the sulfide. 20MnCr5 gear steel was employed and modified with sulfide by Ca treatment and Mg treatment respectively. Through the characterization of mechanical properties, microstructure, inclusion distribution and cutting performance, the influence of different modification methods on the material was compared and analyzed. The results show that the strength and plasticity of steels treated by Ca and Mg are consistent, while the grain size of the sample treated by Mg is smaller, leading to a higher toughness. The amount of MnS inclusions in Ca-treated steel is larger, and the proportion of long strip inclusions is relatively higher by comparing with Mg-treated one. However, Mg treatment can effectively reduce the number of inclusions in steel, increase the average size of inclusions and the number of small aspect ratio inclusions at the same time, however, the number of composite oxide inclusions also increases. The dry cutting tests were carried out at speed range of 240-280 m/min. The results show that both steels appear the front tool surface wear, the flank wear and the boundary wear. The tool wear of the Ca-treated sample is more serious, and the built-up edge and edge breakage phenomenon occur at the higher cutting speed. On the contrary, the sample treated with Mg has a longer tool life and a lower sensitivity to cutting speed. Based on the results obtained, there are more large-size spherical sulfide inclusions in Mg-treated steel, which improves the stress concentration effect and is more conducive to improving the free cutting performance, so the sulfide modification effect is better.
尉文超, 张宵璐, 金国忠, 胡芳忠, 何肖飞. 硫化物改质对20MnCr5齿轮钢夹杂物和切削性能的影响[J]. 钢铁, 2022, 57(5): 99-106.
YU Wen-chao, ZHANG Xiao-lu, JIN Guo-zhong, HU Fang-zhong, HE Xiao-fei. Influence of sulfide modification on inclusions and cutting properties of 20MnCr5 gear steel[J]. Iron and Steel, 2022, 57(5): 99-106.
[1] 陈宣宇,曹建春,周晓龙,等. 国内外易切削钢的研究进展及展望[J]. 热加工工艺,2016,45(24):25. (CHEN Xuan-yu,CAO Jian-chun,ZHOU Xiao-long,et al. Research progress and prospects of free cutting steel in China and abroad[J]. Hot Working Technology,2016,45(24):25.) [2] 姜周华,孙萌,李阳,等. 汽车用特殊钢中夹杂物控制技术的研究进展[J]. 材料与冶金学报,2019,18(3):159.(JIANG Zhou-hua,SUN Meng,LI Yang,et al. State of the art in the control of inclusions in special steel for automobile-A review[J]. Journal of Materials and Metallurgy,2019,18(3):159.) [3] 张盼盼,王冬,沈平,等. 碲对易切削钢硫化物及切削性能的影响[J]. 炼钢,2021,37(3):66. (ZHANG Pan-pan,WANG Dong, SHEN Ping,et al. Effect of tellurium on the sulfide and machinability of free cutting steel[J]. Steelmaking,2021,37(3):66.) [4] 林腾昌,朱荣,姚柳洁,等. 氧含量、温度与铋对易切削钢中MnS形貌的影响[J]. 工程科学学报, 2018,40(增刊1):36.(LIN Teng-chang,ZHU Rong,YAO Liu-jie,et al. Influence of temperature, oxygen and Bi on the morphology of MnS in free-cutting steel[J]. Chinese Journal of Engineering,2018,40(s1):36.) [5] WANG F, GUO H, LIU W, et al. Control of MnS inclusions in high-and low-sulfur steel by tellurium treatment[J]. Materials, 2019, 12: 1034. [6] 谢啸宇,顾超,王敏,等. 中高硫钢中硫化锰夹杂物控制技术[J]. 钢铁, 2021,56(12):52.(XIE Xiao-yu,GU Chao,WANG Min,et al. Manganese sulfide inclusion control technology in medium and high sulfur steel[J]. Iron and Steel,2021,56(12):52.) [7] 张宏艳,田志红,邵肖静,等. 改质工艺对高强度低合金钢夹杂物特性的影响[J]. 中国冶金, 2021,31(2):31.(ZHANG Hong-yan,TIAN Zhi-hong,SHAO Xiao-jing,et al. Influence of modification processes on inclusion properties of high strength low alloy steel[J]. China Metallurgy,2021,31(2):31.) [8] 李超,李建新,姜静宇,等. 钢液成分对钙处理夹杂物改性效果的影响[J]. 中国冶金, 2020,30(10):65.(LI Chao,LI Jian-xin,JIANG Jing-yu,et al. Influence of molten steel composition on modification effect of inclusions during calsium treatment[J]. China Metallurgy,2020,30(10):65.) [9] ZHANG T, LIU C, MU H, et al. Inclusion evolution after calcium addition in Al-killed steel with different sulphur content[J]. Ironmaking and Steelmaking, 2017,45:1. [10] 储晓明,刘全保,王俊超. 含硫易切削钢可浇性的工艺优化[J]. 特钢技术, 2015,21(1):29. (CHU Xiao-ming, LIU Quan-bao, WANG Jun-chao. Optimization of process of castability of free cutting steel with S[J]. Special Steel Technology,2015,21(1):29.) [11] 杨光维,陈兆平,柳向椿. 非钙处理对高等级齿轮钢夹杂物的影响[J]. 钢铁, 2020,55(4):40. (YANG Guang-wei,CHEN Zhao-ping,LIU Xiang-chun. Effect of non-calcium treatment on inclusions in high grade case hardening steel[J]. Iron and Steel,2020,55(4):40.) [12] 艾克南,谢剑波,曾志崎,等. 镁对非调质钢中组织及硫化物的影响[J]. 钢铁研究学报, 2019,31(4):361. (AI Ke-nan,XIE Jian-bo,ZENG Zhi-qi,et al. Effect of Mg on microstructure and sulfide in non-quenched and tempered steel[J]. Journal of Iron and Steel Research, 2019,31(4):361.) [13] 张浩,刘年富, 胡芳忠, 等. 镁对20MnCr5齿轮钢中夹杂物的改质研究[J]. 钢铁研究学报, 2021,33(8):775. (ZHANG Hao,LIU Nian-fu,HU Fang-zhong,et al. Study on modification of inclusions by Mg in 20MnCr5 gear steel[J]. Journal of Iron and Steel Research,2021,33(8):775.) [14] 杨健,蔡文菁. 镁处理对钢中夹杂物以及HAZ组织和性能的影响[J]. 钢铁, 2021,56(7):13.(YANG Jian,CAI Wen-jing. Effect of magnesium treatment on inclusions and HAZ microstructure and properties of steel plate[J]. Iron and Steel,2021,56(7):13.) [15] 艾兴. 高速切削加工技术[M]. 北京:国防工业出版社,2003. (AI Xing. High Speed Cutting Technology[M]. Beijing: National Defense Industry Press,2003.) [16] 于骏一. 机械制造基础[M]. 北京:机械工业出版社,2009. (YU Jun-yi. Fundamentals of Machinery Manufacturing[M]. Beijing: China Machine Press,2009.) [17] 杨海东,邹玉明,张俊生. 切削2种易切钢刀具磨损机理研究[J]. 合肥工业大学学报(自然科学版), 2015,38(7):883. (YANG Hai-dong,ZOU Yu-ming,ZHANG Jun-sheng. Study of wear mechanism of tools by cutting two kinds of free cutting steel[J]. Journal of Hefei University of Technology(Natural Science),2015,38(7):883.) [18] 姚登元,吴华杰,陆鹏雁,等. 钙处理对含硫非调质钢中硫化物形态的影响[J]. 中国冶金, 2017,27(4):11. (YAO Deng-yuan, WU Hua-jie, LU Peng-yan, et al. Effect of Ca treatment on sulfides morphology in S-bearing non-quenched and tempered steel[J]. China Metallurgy,2017,27(4):11.) [19] 林振铭,季清清,朱源,等. 正火温度对 20CrNiMo 齿轮钢显微组织和切削性能的影响[J]. 上海金属, 2016,38(5):43. (LIN Zhen-ming, JI Qing-qing, ZHU Yuan, et al. Influence of normalization temperature on microstructure and cutting property of 20CrNiMo gear steel[J]. Shanghai Metals,2016,38(5):43.) [20] SUN H, WU L P, XIE J B, et al. Inclusions modification and improvement of machinability in a non-quenched and tempered steel with Mg treatment[J]. Journal of Metallurgical Research, 2020,117(2):208.