【作者】 钱华；

【导师】 陈明； 刘玉文；

【作者基本信息】 上海交通大学 ， 机械工程， 2012， 硕士

【摘要】 螺纹量规是油井管生产中必不可少的重要量具。为满足螺纹量规的使用要求，一般选用冷作模具钢或轴承钢等材料，通过淬火、回火和时效处理后采用磨削方法加工。由于热处理不当而造成后续加工磨削烧伤和磨削裂纹缺陷，以及使用中磨损严重，是螺纹量规生产中面临的两大难题，势必对油井管加工的质量和成本带来极大的威胁。因此，针对螺纹量规生产选择合理的热处理方法和工艺参数对降低钢管企业的制造成本和制造水平具有重大的现实意义。本文采用正交试验的方法，通过热处理工艺试验和磨削加工试验，分析了不同热处理工艺对螺纹量规耐磨性和冷作模具钢9Mn2V磨削加工性能的影响。9Mn2V冷作模具钢采用淬火+冷处理+回火+时效处理工艺后，得到针状马氏体+残余奥氏体+颗粒状碳化物的组织，可以满足螺纹量规的使用条件和加工性能要求。针对不同的热处理工艺，淬火温度对材料组织和性能影响最大，其次是回火时间和时效。由于残余奥氏体含量对硬度、尺寸稳定性和材料耐磨性影响较大，需通过增加冷处理或深冷处理等工艺加以控制或消除，但深冷处理对硬度影响不显著。通过磨削加工试验发现，淬火工件磨削表层的热影响区最深，回火后工件的热影响区明显减小。而增加回火次数，延长回火时间可促进过饱和马氏体析出ε-碳化物并改善正方度，起到第二相强化和提高马氏体稳定性的作用，可有效降低材料组织残余应力，减少和消除磨削裂纹的产生诱因，改善9Mn2V的磨削加工性能。根据热处理工艺和磨削加工试验分析，在现有装备的基础上，本文通过改进原有冷作模具钢9Mn2V热处理工艺路线，并通过宝钢自制螺纹量规的生产实践进行了检验，取得了较好的实际效果。更多还原

【Abstract】 Thread gauge is an indispensable measuring tool in the manufacturing of oilcountry tubular goods (OCTG). Generally, thread gauge is made by cold work diesteel and bearing steel to meet the use requirement, using the grinding method ofprocessing after heat treatment involved quenching, tempering and aging treatment.Due to improper heat treatment, grinding defects involved grinding burns and grindingcracks, and badly worn in using process, are two major problems in thread gaugeproducing and using, it would bring a great risk to the quality control and cost waste ofthe OCTG. Therefore, to improve the heat treatment process is of great practicalsignificance for the thread gauge manufacturing to reduce the manufacturing cost ofOCTG.Through orthogonal experiment and other studying methods, this paper uses heattreatment process test and grinding processing experiment for analysis of the influenceon the thread gauge wear resistance and cold work die steel9Mn2V grindingprocessing performance under different heat treatment processes. The cold work diesteel9Mn2V could get an organization of acicular martensite, residual austenite andgranular carbide after quenching, cold treatment, tempering and aging treatmentprocess, which meets the requirements of service conditions and processing propertiesof the thread gauge. For different heat treatment processes, the quenching temperaturemakes greatest impact on the material microstructure and properties, followed bytempering time and aging. The residual austenite content has a big influence onhardness, dimensional stability and material wear resistance, which can be controlledor eliminated by adding the cold treatment or cryogenic treatment process, but thedeep cryogenic treatment has no significant impact on the hardness.Through the grinding process tests, the results indicated that the heat affectedzone of the quenching workpiece grinding surface was deepest, but significantlyreduced after tempering. With the increase of the time of tempering and the extendedtempering time, supersaturated martensite could be promoted to separate out ε-carbide,which made the square degree improved. This change led to a second phase strengthening and better martensite stability, which could effectively reduce theresidual stress of the material organization and eliminate the grinding cracksincentives, and improved the9Mn2V grinding performance eventually.According to the analysis of heat treatment process and grinding test, this paperimproved the route of the original cold work die steel9Mn2V heat treatment process,and the practical results of the thread gauge indicated that the optimal heat treatmentprocess based on the the existing equipment in Baosteel was actually effective.更多还原