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.
作者
杨金艳
赵灵杰
成亚维
Yang Jinyan;Zhao Lingjie;Cheng Yawei(Nantong Products Quality Supervision and Inspection Institute,Nantong Jiangsu 226011,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2019年第6期215-219,共5页
Heat Treatment of Metals
基金
江苏省质量技术监督局科技项目(KJ185644)
