风电内齿圈感应淬火裂纹形成原因及改进方法

Causes and improvement methods of induction quenching cracks in wind power inner gear ring

从宏观形貌、显微组织、脱碳层和偏析等方面分析了风电内齿圈感应淬火开裂问题。分析表明,锻件的碳偏析、脱碳是导致内齿圈感应淬火开裂的重要原因,内齿圈的碳偏析程度达到0.04%以上时,增加了感应淬火开裂的风险,同时齿顶脱碳加剧了感应淬火开裂的风险。实际工艺改进表明,采用三向锻造的方式获得锻造比大于7的坯料,内齿圈碳偏析差可降低至0.02%,能有效改善碳偏析。在冲孔工艺设计时,可以通过控制冲孔质量来实现连铸坯中心部位偏析的消除,当下料系数大于0.019时,可避免齿部显微缺陷和淬火开裂的产生。

Induction hardening cracking of the inner gear ring of wind power was analyzed from the aspects of macro morphology,microstructure,decarburization layer and segregation.The analysis results show that carbon segregation and decarburization of forgings are important reasons for induction hardening cracking of the inner gear ring.When the carbon segregation degree of inner gear ring reaches above 0.04%,the risk of induction hardening cracking increases,and decarburization of tooth tip intensifies the risk of induction hardening cracking.The actual process improvement shows that the carbon segregation difference of the inner gear ring can be reduced to 0.02% by obtaining the blank with forging ratio greater than 7 by three-way forging,which can effectively avoid the carbon segregation.In the design of punching process,the segregation in the center of continuous casting slab can be eliminated by controlling the punching quality.When the blanking coefficient is greater than 0.019,the generation of micro defects and quenching cracks in the teeth can be avoided.