|
|
|
| Effect of Al and N contents on austenite grain size for high-temperature carburized gear steels |
| WEI Min1, DENG Wei2, TANG Hai-yan1, LI Hai-yang2, WANG De-jiong2, ZHANG Jia-quan1 |
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083,China;
2. Special Steel Department, Nanjing Iron and Steel Co., Ltd., Nanjing 210035, Jiangsu, China |
|
|
|
|
Abstract As high-end gear steels for rail transit need a long-time and high-temperature carburizing heat-treatment to improve their surface hardness and wear resistance,the key to ensure a fine microstructure and geometrical accuracy for the steels is to select appropriate Al and N contents to pin austenite grain boundary with their precipitated AlN particles. AlN particles have undergone partial solution at the usual carburizing temperature. In order to ensure a fine austenite grain size after high temperature carburizing,the content of acid-soluble aluminum in gear steel generally needs to be kept between 0.02% and 0.055%,and the content of N is required to be 0.01%-0.016% to ensure the precipitation of sufficient fine AlN second phase particles to pin grain boundaries. As the ranges of Al and N content are wide,the study of appropriate Al and N contents,the ratio of Al and N mass percents and the pinning effect of AlN particles on austenite during high temperature carburizing of steel is necessary. Pseudo carburizing experiments of the steels with various Al and N contents were conducted,and the ripening model of the second phase particle and its Gladman pinning model were studied. As a result,a quantitative expression for the non-uniformity factor Z and temperature T was revealed. Furthermore,the growth trends of austenite grain radius RA during high temperature carburizing process were observed,and the effect of different products and ratios of Al and N on austenite grain-coarsening behavior were analyzed accordingly. The results show that for carburizing temperature range of 1 173-1 273 K,the Z factor of austenite grains obeys a linear law of Z=3.742 97-0.001 76T. With a given holding time t,lnRA has a quadratic polynomial relationship with 1/T,but lnRA is linearly related to lnt while under a constant heating temperature T,and the time exponent of austenite grain growth is 0.33. When the product of w(Al) and w(N) exceeds 4.77×10-4,namely the austenite-grain coarsening temperature exceeds 1 263 K,the austenite grains can outnumber grade 7 even after 6 h holding at T=TC-10 K provided the ratios of w(Al) and w(N) of the steels are between 1.5-3.8. With a given product of w(Al) and w(N),the size of austenite grains after the same heating history shows a linear positive correlation with its ratio of w(Al) and w(N),and the size difference of the austenite grains is within grade 1 for steels with Al-N ratios ranged from 1.5 to 3.8.
|
|
Received: 16 June 2022
|
|
|
|
[1] 张国强,何肖飞,尉文超,等. 高温渗碳齿轮钢的晶粒粗化行为[J]. 钢铁,2019,54(5):68.(ZHANG Guo-qiang,HE Xiao-fei,YU Wen-chao,et al. Grain coarsening behavior of high temperature carburizing gear steels[J]. Iron and Steel,2019,54(5):68.)
[2] Wada T. Diffusion modeling of the carburization process[J]. Metallurgical and Materials Transactions,1980,11A:1076.
[3] 王远琦,陈小伟,李志华,等. Nb-Ti微合金钢中的奥氏体晶粒长大行为研究[J]. 钢铁,2010,45(4):72.(WANG Yuan-qi,CHEN Xiao-wei,LI Zhi-hua,et al. Austenite grain growth behavior in Nb-Ti microalloyed steel[J]. Iron and Steel,2010,45(4):72.)
[4] Fink W L. Precipitation hardening[J]. Journal of Applied Physics,1942,13:75.
[5] 郑丽丽,彭军,安胜利,等. Mo、Ce对贝氏体钢第二相及组织与硬度的影响[J]. 中国冶金,2021,31(7):50.(ZHENG Li-li,PENG Jun,AN Sheng-li,et al. Effect of Mo and Ce on the second phase,microstructure and hardness of bainite steel[J]. China Metallurgy,2021,31(7):50.)
[6] Zener C. Theory of growth of spherical precipitates from solid solution[J]. Journal of Applied Physics,1949,20:950.
[7] Hellman P,Hillert M. On the effect of second-phase particles on grain growth[J]. Scandinavian Journal of Metallurgy,1975,4:211.
[8] Wörner C H,Cabo A. On the grain growth inhibition by second phases particles[J]. Acta Metallurgica,1987,35:2801.
[9] Gladman T. On the theory of the effect of precipitate particles on grain growth in metals[J]. Proceedings of the Royal Society London,1966,294A:298.
[10] 侯雨阳,成国光. Nb对双稳定铁素体不锈钢晶粒的钉扎作用[J]. 连铸,2018,43(3):55.(HOU Yu-yang,CHENG Guo-guang. The pinning effect of Nb on the ferrite stainless steel grains[J]. Continuous Casting,2018,43(3):55.)
[11] 柳得橹,王元立,霍向东,等. CSP低碳钢的晶粒细化与强韧化[J]. 金属学报,2002,38(6):647.(LIU De-lu,WANG Yuan-li,HUO Xiang-dong,et al. Grain refinement and strengthening of low carbon steel by CSP technology[J]. Acta Metallurgica Sinica,2002,38(6):647.)
[12] 王学伦,宋介中,王巍. 二相粒子/析出相钉扎晶界模型研究进展[J]. 钢铁研究学报,2010,22(12):1.(WANG Xue-lun,SONG Jie-zhong,WANG Wei. Development of analytical model for grain boundary pinned by second-phase particle[J]. Journal of Iron and Steel Research,2010,22(12):1.)
[13] 戚正风,张从尧. 奥氏体起始晶粒的不均匀因子Z0[J]. 金属热处理学报,1990,11(3):24.(QI Zheng-feng,ZHANG Cong-yao. The nonuniform factor Z0 of initial austenite grain[J]. Transactions of Metal Heat Treatment,1990,11(3):24.)
[14] 李明贤,朱国军. 氮质量分数对铸坯角部裂纹的影响及控制[J]. 中国冶金,2017,27(6):54.(LI Ming-xian,ZHU Guo-jun. Effect and control of nitrogen mass fraction on slab corner crack[J]. China Metallurgy,2017,27(6):54.)
[15] Darken L S,Smith R P,Filer E W. Solubility of gaseous N in gamma iron and the effect of alloying constituents—Al nitride precipitation[J]. Journal of Metals Materials and Minerals,1951,3:1174.
[16] Zhang X G,Matsuura K,Ohno M. Abnormal grain growth in austenite structure reversely transformed from ferrite/pearlite-banded structure[J]. Metallurgical and Materials Transactions,2014,45A:4623.
[17] Boyer H E,Gall T L. Metals Handbook;Desk Edition Vol.1 Properties and Selection:Irons,Steels,and High-Performance Alloys[M]. Ohio:American Society for Metals,1985.
[18] Villars P,Calvert L D. Pearson's Handbook of Crystallographic Data for Intermediate Phases[M]. Ohio:American Society for Metals,1985.
[19] Ardell A J. The effect of volume fraction on particle coarsening:Theoretical considerations[J]. Acta Metallurgica,1972,20:61.
[20] KANG Y L,YU H,FU J,et al. Morphology and precipitation kinetics of AlN in hot strip of low carbon steel produced by compact strip production[J]. Materials Science Engineering,2003,A351:265.
[21] 刘华松,董延楠,郑宏光,等. Nb微合金化对齿轮钢高温渗碳奥氏体晶粒度的影响[J]. 钢铁研究学报,2021,33(8):11.(LIU Hua-song,DONG Yan-nan,ZHENG Hong-guang,et al. Influence of Nb microalloying on grain size of austenite in high-temperature carburized gear steel[J]. Journal of Iron and Steel Research,2021,33(8):11.)
[22] 雍岐龙. 钢铁材料中的第二相[M]. 北京:冶金工业出版社,2006.(YONG Qi-long. Second Phase in Structural Steels[M]. Beijing:Metallurgical Industry Press,2006.)
[23] Okaguchi S,Hashimoto T. Computer model for prediction of carbonitride precipitation during hot working in Nb-Ti bearing HSLA steels[J]. ISIJ International,1992,32:283.
[24] 张壮,李海洋,周蕾,等. 齿轮钢铸态点状偏析及其在热轧棒材中的演变[J]. 金属学报,2021,57(10):1281.(ZHANG Zhuang,LI Hai-yang,ZHOU Lei,et al. As-cast spot segregation of gear steel and its evolution in the rolled products[J]. Acta Metallurgica Sinica,2021,57(10):1281.)
[25] Wilson F G,Gladman T. Aluminium nitride in steel[J]. International Materials Review,1988,33:221.
[26] 洪钢,刘华松,董延楠,等. 微合金包晶钢高温奥氏体晶粒生长动力学研究[J]. 钢铁研究学报,2021,33(12):1270.(HONG Gang,LIU Hua-song,DONG Yan-nan,et al. Study on kinetics of austenite grain growth of micro-alloyed peritectic steels under high temperatures[J]. Journal of Iron and Steel Research,2021,33(12):1270.)
[27] 党淑娥,宿展宁,刘志龙,等. 30Cr2Ni4MoV钢铸态加热过程中奥氏体晶粒的长大行为[J]. 材料研究学报,2014,28(9):675.(DANG Shu-e,SU Zhan-ning,LIU Zhi-long,et al. Austenite grain growth behavior during heating process of as-cast 30Cr2 Ni4MoV steel[J]. Chinese Journal of Materials Research,2014,28(9):675.) |
| [1] |
XING Jun, ZHU Guo-hui, DING Han-lin, PU Chun-lei, WANG Yong-qiang, LIU Shu-lan. Microalloying design for microstructure refinement in hot rolled H-beam steels based on specifications[J]. Iron and Steel, 2023, 58(3): 144-150. |
| [2] |
ZHANG Shao-long, ZHOU Wen, HU Feng, WU Kai-ming, PAN Xian-ming. Effect of Mn on tempering stability of retained austenite in bainite steel[J]. Iron and Steel, 2023, 58(2): 113-125. |
| [3] |
WANG Zhuo1,2，ZHU Hong2，XU Bin3,4，SONG Danrong3,4，WANG Liubing3,4，ZHANG Hongliang3,4. Prediction of mechanical properties of austenitic stainless steel for nuclear power based on machine learning algorithm[J]. JOURNAL OF IRON AND STEEL RESEARCH , 2023, 35(2): 201-209. |
| [4] |
FAN Bin, LIU Li, ZHANG Shi-yu, LIU Ning-ning, LIU Xiao-ming, WANG Qiang. Gear steel 20CrMnTiH hardenability/macro segregation control[J]. CONTINUOUS CASTING, 2023, 42(1): 47-54. |
| [5] |
ZHAO Jie1,2，WAN Xiangliang1，KE Rui2，HU Feng2，WU Kaiming2. Effect of grain refinement on mechanical properties of austenitic stainless steels at high temperature[J]. JOURNAL OF IRON AND STEEL RESEARCH , 2023, 35(1): 88-97. |
| [6] |
WANG Jun-cai, CAO Jian-chun, ZENG Min, LUO Han-yu, WANG Chuang-wei, YE Xiao-yu. Effect of Zr content on austenite microstructure of high-strength and high-toughness Ti-Zr microalloyed steel[J]. Iron and Steel, 2023, 58(1): 133-140. |
|
|
|
|
2022, Vol. 57 
