20CrMnTi钢渗碳齿轮表面裂纹形成原因
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摘要
采用现代分析手段对20CrMnTi渗碳齿轮表面裂纹形成原因进行了分析。发现裂纹沿晶界分布,且裂纹两侧存在脱碳现象,裂纹内侧通过能谱分析存在大量氧、硫元素。裂纹两侧组织为呈网状条块铁素体+高碳细小回火组织,基体组织为回火马氏体组织,边缘渗碳处的组织为高碳细小回火组织。结果表明:20CrMnTi钢渗碳齿轮表面裂纹形成的主要原因是锻造过程中加热温度太高而过烧,由过烧形成的熔洞以及未熔化的低熔点化合物使晶粒与晶粒之间结合力降低,一经锻打便会碎裂。这种由过烧引起的熔洞与裂纹,再次淬火加热过程中,受到热应力的作用下,进一步扩展成断断续续的裂纹。
The causes of surface cracks in carburized gear of 20 CrMnTi were studied by modern analytical means. It is found that the cracks are distributed along the grain boundaries,and decarburization occurred on both sides of the crack. There are a large amount of oxygen and sulfur elements in the crack by energy spectrum analysis. The microstructure on both sides of the crack is networked ferrite and fine tempered structure with high carbon,the matrix structure is tempered martensite,and the microstructure at the edge carburizing was fine tempered structure with high carbon. The results show that the main reason for the formation of surface cracks is that the heating temperature is too high and overburnt during forging,melting holes and unmelted low-melting compounds formed by overburning reduce the bonding force between the grains and resulting to cracking as soon as it is forged. In reheating quenching,the holes and cracks caused by overburning would further expand into intermittent cracks under the action of thermal stress.
The causes of surface cracks in carburized gear of 20 CrMnTi were studied by modern analytical means. It is found that the cracks are distributed along the grain boundaries,and decarburization occurred on both sides of the crack. There are a large amount of oxygen and sulfur elements in the crack by energy spectrum analysis. The microstructure on both sides of the crack is networked ferrite and fine tempered structure with high carbon,the matrix structure is tempered martensite,and the microstructure at the edge carburizing was fine tempered structure with high carbon. The results show that the main reason for the formation of surface cracks is that the heating temperature is too high and overburnt during forging,melting holes and unmelted low-melting compounds formed by overburning reduce the bonding force between the grains and resulting to cracking as soon as it is forged. In reheating quenching,the holes and cracks caused by overburning would further expand into intermittent cracks under the action of thermal stress.
引文
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[14]杨梅,张春枝,李志军.45钢调质活塞杆裂纹分析[J].热加工工艺,2013,42(1):224-226.Yang Mei,Zhang Chunzhi,Li Zhijun.Crack analysis of 45 steel quenching and tempering piston rod[J].Hot Working Technology,2013,42(1):224-226.
[15]蔡晓文.S48C锻件开裂原因分析与研究[J].热加工工艺,2013,42(23):203-206.Cai Xiaowen.Analysis and study on cracking causes of S48C steel forgings[J].Hot Working Technology,2013,42(23):203-206.
[16]刘雅辉,刘淑梅,于秋华.精锻齿轮坯缺陷分析及工艺改进[J].热加工工艺,2014,43(11):109-111.Liu Yahui,Liu Shumei,Yu Qiuhua.Defect analysis and process improvement of precision forging gear billet[J].Hot Working Technology,2014,43(11):109-111.
[2]曹晶晶,赵文武,李阳.37Mn5热轧钢管内壁裂纹失效分析[J].金属热处理,2016,41(1):228-232.Cao Jingjing,Zhao Wenwu,Li Yang.Failure analysis on inner surface crack of 37Mn5 hot-rolled steel tube[J].Heat Treatment of Metals,2016,41(1):228-232.
[3]姚艳书,高见,金晶.铁路货车轴承裂纹分析[J].金属热处理,2001,26(3):40-42.Yao Yanshu,Gao Jian,Jin Jing.Crack analysis of goods train bearing[J].Heat Treatment of Metals,2001,26(3):40-42.
[4]温宏权,向顺华,张永杰.60Si2Mn弹簧钢加热温度对表面脱碳的影响[J].宝钢技术,2008,138(3):44-47.Wen Hongquan,Xiang Shunhua,Zhang Yongjie.Effect of heating temperature on surface decarburization of spring steel 60Si2Mn[J].Baosteel Technology,2008,138(3):44-47.
[5]孔祥华,唐晋,孙瑞虹.SCM440钢表面脱碳与开裂[J].材料热处理学报,2012,33(3):142-145.Kong Xianghua,Tang Jin,Sun Ruihong.Surface decarburization and cracking behavior of SCM440 steel[J].Transactions of Materials and Heat Treatment,2012,33(3):142-145.
[6]李红英,陈广,唐薇.汽车悬架用弹簧钢铁素体全脱碳行为研究[J].材料科学与工艺,2014,22(4):49-55.Li Hongying,Chen Guang,Tang Wei.Studies of ferrite decarburization behavior in spring steel for automotive suspensions[J].Material Science and Technology,2014,22(4):49-55.
[7]于俊.钢轨钢为什么用高碳钢[J].金属世界,1994(2):13.
[8]王文健,张向龙,张继旺,等.碳含量对车轮钢滚动摩擦磨损性能影响[J].铁道学报,2012,34(2):32-35.Wang Wenjian,Zhang Xianglong,Zhang Jiwang,et al.Effect of carbon content on rolling friction and wear behavior of wheel steel[J].Journal of the China Railway Society,2012,34(2):32-35.
[9]徐咏梅.锻造及热处理工艺对MC5冷轧辊坯缺陷与组织性能的影响[D].哈尔滨:哈尔滨工业大学,2014.
[10]罗怀晓,李云.ZG25铸钢件裂纹产生原因分析[J].铸造技术,2017,38(1):120-121.Luo Huaixiao,Li Yun.Cause analysis of cracks in ZG25 steel castings[J].Foundry Technology,2017,38(1):120-121.
[11]杨争,仵永刚,魏建文,等.轴承外圈缺陷分析[J].金属热处理,2014,39(9):154-157.Yang Zheng,Ni Yonggang,Wei Jianwen.Analysis of defect on bearing outer ring[J].Heat Treatment of Metals,2014,39(9):154-157.
[12]孙钦贺.轴承套圈锻造过程缺陷分析[J].金属加工(热加工),2015,732(9):77-78.
[13]张梅,冯继军,黄文长,等.曲轴连杆轴颈裂纹原因分析[J].汽车工艺与材料,2011,271(7):25-30.
[14]杨梅,张春枝,李志军.45钢调质活塞杆裂纹分析[J].热加工工艺,2013,42(1):224-226.Yang Mei,Zhang Chunzhi,Li Zhijun.Crack analysis of 45 steel quenching and tempering piston rod[J].Hot Working Technology,2013,42(1):224-226.
[15]蔡晓文.S48C锻件开裂原因分析与研究[J].热加工工艺,2013,42(23):203-206.Cai Xiaowen.Analysis and study on cracking causes of S48C steel forgings[J].Hot Working Technology,2013,42(23):203-206.
[16]刘雅辉,刘淑梅,于秋华.精锻齿轮坯缺陷分析及工艺改进[J].热加工工艺,2014,43(11):109-111.Liu Yahui,Liu Shumei,Yu Qiuhua.Defect analysis and process improvement of precision forging gear billet[J].Hot Working Technology,2014,43(11):109-111.