摘要
为了突破单一激光淬火硬化层深度较浅的局限性,采用激光和电磁感应双热源耦合方法进行复合淬火,以提高重载工况下42CrMo钢的硬化层深度。设计了滚动体-圆盘线接触滚动疲劳试验装置,分析了硬化层深度对42CrMo钢滚动接触疲劳性能的影响。使用扫描电镜、显微硬度计、激光共聚焦等设备分析了不同深度硬化层在模拟风电主轴轴承套圈与滚动体配合使用下的滚动疲劳损伤机理。结果表明:在相同的疲劳试验条件下,当硬化层深度达到6.3mm时,磨损表面损伤程度有所减轻,磨痕深度降低到23.61μm,表层裂纹扩展角度下降到15°,裂纹长度减小到400μm,同时扩展受到阻碍。硬化层深度为6.3 mm的试样沿X和Y方向的最大压应力分别达440.3MPa和395.3MPa,并且一定的残余压应力可以提高材料的接触疲劳性能。该研究结果可为重载轴承的深层强化提供参考。
Objective The rapid development in the field of wind power presents high requirements on the surface contact fatigue performance of the raceways of wind-power main-shaft bearing rings.The commonly used material for the raceway of wind-turbine main-shaft bearing ring is 42CrMo steel.Therefore,to overcome the limitation of the hardened layer depth through laser quenching,dual heat sources coupled with electromagnetic induction and laser are used for hybrid quenching to increase the hardened layer depth on 42CrMo steel,obtain excellent rolling contact fatigue performance for the bearing ring under heavy load conditions,and prolong its service life.This study also provides a reference for the deep strengthening of heavy-duty bearings.Methods To simulate the use of wind-turbine main-shaft bearing rings and rolling elements,the fixture of a MUG-5Ztesting machine was modified and designed.The contact form of a rolling wear test device was rolling element-disc type(Fig.5).The test force was set to 3646N;therefore,the average load Fapplied to the specimen was 1215.3N,whereas the maximum contact stress calculated using formula(3)was 2.5GPa.To analyze the effect of different hardened layer depths on the rolling contact fatigue performance of laser-induction hybrid quenched 42CrMo steel,three groups of specimens with the hardened layer depths of 3.5,4.5,and 6.3mm were prepared for a rolling wear test(Fig.3).The contact forms were all line contact.Moreover,the rotation speed was set to 2500r/min,whereas the test period was 1.08×10~7.According to GB/T 10510—2005,N32oil was used for lubrication,and the test was repeated three times on each specimen under each set of test conditions.To evaluate the fatigue performance of the laser-induction hybrid quenched specimen,the surface morphology,three-dimensional morphology,and twodimensional profile of the rolling contact fatigue specimen were observed using EVO18scanning electron microscope(SEM)and DSX1000ultra-depth-of-field microscope.Furthermore,the X-ray energy dispersive spectrometer(EDS)was used to scan the cracking area to analyze the element distribution and explore the fatigue damage mechanism.Results and Discussions Herein,the deep hardening of a heavy-duty bearing material is realized using the laserinduction hybrid quenching process(Fig.2).With an increase in the hardened layer depth,the residual compressive stress near the corresponding surface layer increases significantly(Fig.7),and the paired position of the main and companion specimens corresponds to the maximum residual compressive stress region.The residual compressive stress can offset the tensile stress caused by the microplastic deformation of the specimen in rolling contact motion,increasing its ability to inhibit crack propagation,preventing effectively crack initiation and propagation to a certain extent,and improving the fatigue life of the material.When the hardened layer depth increases to 6.3mm,the surface damage of the specimen is further alleviated,and the phenomena of cracking and shallow spalling occur on the surface.Further,the surface wear scar depth reduces to 23.61μm(Fig.8,Fig.9).Simultaneously,there are no large spalling pits in the section,the crack propagation angle is approximately 15°,and the cross-sectional crack length is the shortest(Fig.12).The experimental results show that when the hardened layer depth increases,the crack propagation angle and crack length become smaller and the surface damage shows a decreasing trend,which indicates that the laser-induction hybrid quenching can effectively improve the rolling contact fatigue performance of the material.The rolling fatigue failure mechanism of the laser-induction hybrid quenched on 42CrMo steel under heavy load conditions is obtained by analyzing the surface damage and cross-sectional crack propagation.The fatigue failure mainly results from the surface and internal spalling(Fig.13,Fig.14).Conclusions The maximum-hardened layer depth of 6.3 mm can be obtained from the laser-induction hybrid quenched process on 42CrMo steel.The results show that the specimen with the hardened layer depth of 6.3mm has the lowest surface damage,shallowest surface wear scar depth,shortest cross-sectional crack length,and best rolling contact fatigue performance among three specimens.After laser-induction hybrid quenching,a certain residual compressive stress exists on the specimen surface,which can improve the rolling contact fatigue performance of the material.As the depth of the hardened layer increases,the fatigue failure type of laser-induction hybrid quenched42CrMo steel under heavy load conditions changes from external cracking to internal cracking and spalling.The angle between the cracks and surface decreases from 90°to 15°.While the crack propagation angle reduces,the crack extension becomes smoother and the rolling wear and fatigue damage of the specimen are alleviated.
作者
张群莉
黄华
唐泽浩
李国昌
牛庆安
陈智君
杜杨琼
姚建华
Zhang Qunli;Huang Hua;Tang Zehao;Li Guochang;Niu Qing’an;Chen Zhijun;Du Yangqiong;Yao Jianhua(Institute of Laser Advanced Manufacturing,Zhejiang University of Technology,Hangzhou,Zhejiang 310023,China;Collaborative Innovation Center of High-End Laser Manufacturing Equipment(National“2011 Plan”),Zhejiang University of Technology,Hangzhou,Zhejiang 310023,China;Zhongzhe High-Speed Railway Bearing Co.,Ltd.,Quzhou,Zhejiang 324407,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第8期244-255,共12页
Chinese Journal of Lasers
基金
国家重点研发计划(2018YFB0407301)
浙江省“尖兵”“领雁”研发攻关计划(2022C03021)
浙江省属高校基本科研业务费项目(RF-C2019003)。
