GCr15钢中的离异共析转变
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摘要
利用Gleeble 3500型热模拟实验机,测定了GCr15钢共析转变温度区间。通过扫描电镜和硬度测试,研究了奥氏体化温度和时间对碳化物颗粒形态及分布的影响,分析了GCr15钢共析转变过程中的显微组织变化及其影响因素。结果表明:GCr15钢不完全奥氏体化,有助于离异共析转变的发生。在共析转变温度区间存在一临界点,从共析转变开始点到该临界点,GCr15钢共析转变的主要方式为离异共析转变,直接形成球状珠光体组织;从临界点到共析转变结束点,共析转变过程中出现片状珠光体,在此区间内,随温度的下降,片状珠光体转变逐渐趋于主导。利用离异共析转变,GCr15钢可直接获得完全的球状珠光体组织,碳化物平均尺寸为1. 35μm,布氏硬度为181 HBW左右,球化时间可缩短到6.5 h。
Eutectoid transformation temperature interval of GCr15 steel was determined by the Gleeble 3500 heat simulation experiment machine. The effects of austenitizing temperature and time on the morphology of particles of GCr15 steel heating in the box-type furnace were investigated by means of SEM and hardness testing,and the microstructure change and its influence factors in the process of eutectoid transformation of GCr15 steel were analyzed. The results show that it is helpful for the divorced eutectic transformation of GCr15 steel when it is incompletely austenitized. There is a critical point between eutectoid transformation temperature ranges. From the eutectoid transformation staring point to the critical one as cooling,the divorced eutectoid transformation of GCr15 steel is dominant,which produces the spheroidal pearlite directly during the transformation. From the critical point to the end one of eutectoid transformation finishing,the laminar pearlite can be observed during the eutectoid transformation process. And with the decrease of temperature,the transformation of the laminar pearlite gradually tended to dominate. GCr15 steel can directly obtain the complete spherical pearlitic microstructure by using the divorce eutectoid transformation. The average size of the spherical carbide is about 1. 35 μm,the hardness is about 181 HBW. As well as the spherification time can be shortened to 6.5 h.
Eutectoid transformation temperature interval of GCr15 steel was determined by the Gleeble 3500 heat simulation experiment machine. The effects of austenitizing temperature and time on the morphology of particles of GCr15 steel heating in the box-type furnace were investigated by means of SEM and hardness testing,and the microstructure change and its influence factors in the process of eutectoid transformation of GCr15 steel were analyzed. The results show that it is helpful for the divorced eutectic transformation of GCr15 steel when it is incompletely austenitized. There is a critical point between eutectoid transformation temperature ranges. From the eutectoid transformation staring point to the critical one as cooling,the divorced eutectoid transformation of GCr15 steel is dominant,which produces the spheroidal pearlite directly during the transformation. From the critical point to the end one of eutectoid transformation finishing,the laminar pearlite can be observed during the eutectoid transformation process. And with the decrease of temperature,the transformation of the laminar pearlite gradually tended to dominate. GCr15 steel can directly obtain the complete spherical pearlitic microstructure by using the divorce eutectoid transformation. The average size of the spherical carbide is about 1. 35 μm,the hardness is about 181 HBW. As well as the spherification time can be shortened to 6.5 h.
引文
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[13]《钢铁材料手册》总委员会.钢铁材料手册.第9卷,轴承钢[M].北京:中国标准出版社,2004.
[2]Zaretsky E V.Rolling bearing steels-a technical and historical perspective[J].Materials Science and Technology,2013,28(1):58-69.
[3]闫文凯,杨卯生,杜景红,等.高纯净GCr15轴承钢组织演变与快速球化工艺的研究[J].钢铁,2010,45(12):63-67.Yan Wengang,Yang Maosheng,Du Jinghong,et al.Microstructure evolution and rapid spheroidizing technology of high-purity of GCr15bearing steel[J].Iron and Steel,2010,45(12):63-67.
[4]Kamyabi-Gol A,Sheikh-Amiri M.Spheroidizing kinetics and optimization of heat treatment parameters in CK60 steel using taguchi robust design[J].Journal of Iron and Steel Research International,2010,17(4):45-52.
[5]Bhadeshia H K D H.Steels for bearings[J].Progress in Materials Science,2012,57(2):268-435.
[6]Zhu G H,Zheng G.Directly spheroidizing during hot deformation in GCr15steels[J].Frontiers of Materials Science in China,2008,2(1):72-75.
[7]Verhoeven J D.The role of the divorced eutectoid transformation in the spheroidization of 52100 steel[J].Metallurgical and Materials Transactions A,2000,31(10):2431-2438.
[8]穆志勇,王毓德.GCr15钢在离异共析转变过程中临界过冷度的物理模型推导及验证[J].铸造技术,2015(1):43-45.Mu Zhiyong,Wang Yude.Derivation and validation of physical model on critical undercooling of steel GCr15 during divorced eutectoid transformation[J].Foundry Technology,2015(1):43-45.
[9]丁美良,关建辉.GCr15钢离异共析转变前沿生长速度的计算[J].热处理技术与装备,2013,34(5):8-11.Ding Meiliang,Guan Jianhui.Calculation for growth rate of divorced eutectoid transformation front in GCr15 steel[J].Heat Treatment Technology and Equipment,2013,34(5):8-11.
[10]Verhoeven J D,Gibson E D.The divorced eutectoid transformation in steel[J].Metallurgical and Materials Transactions A,1998,29(4):1181-1189.
[11]Oyama T,Sherby O D,Wadsworth J,et al.Application of the divorced eutectoid transformation to the development of fine-grained,spheroidized structures in ultrahigh carbon steels[J].Scripta Metallurgica,1984,18(8):799-804.
[12]陈其伟,关建辉,朱国辉,等.GCr15钢快速球化中离异共析转变临界过冷度的物理模型[J].材料热处理学报,2013,34(4):182-186.Chen Qiwei,Guan Jianhui,Zhu Guohui,et al.Physical model for critical undercooling of divorced eutectoid transformation in fast spheroidization annealing of GCr15 steel[J].Transactions of Materials and Heat Treatment,2013,34(4):182-186.
[13]《钢铁材料手册》总委员会.钢铁材料手册.第9卷,轴承钢[M].北京:中国标准出版社,2004.