微合金化齿轮钢组织性能研究
发布时间：2018-12-10 07:06
【摘要】：20Cr2Ni4是一种常见的重载齿轮钢,虽然目前在工业系统中广泛应用,但是还存在生产加工性能较差和使用寿命较短等问题,不能满足我国现代工业产业的转型对重载齿轮钢的质量要求。本文在20Cr2Ni4钢的化学成分基础上,用元素V和Nb对20Cr2Ni4钢微合金化,制备了包括母合金(20Cr2Ni4)在内的四种试验钢,研究了微合金化对齿轮钢晶粒长大规律的影响。通过对比试验钢的整体强化后的组织与力学性能、淬透性和渗碳处理后的性能,研究了微合金元素对齿轮钢的强化作用。对试验钢显微组织的观察研究表明,由于V和Nb的微合金化,试验钢G1、G2、G3的显微组织中出现了它们的碳化物和氮化物。在奥氏体化的加热过程中,这些化合物并未完全溶解,它们阻碍奥氏体晶界迁移,细化了奥氏体晶粒。在加热温度为880℃～960℃,保温时间为10小时的实验条件下,试验钢G1、G2、G3显微组织中的奥氏体晶粒度随温度的升高变化不大,而未添加微合金元素的试验钢G4中奥氏体晶粒明显长大。同一温度下,G1、G2、G3钢的奥氏体晶粒度等级比G4钢高3～5级。其中添加了复合微合金元素Nb和V的G2钢晶粒度等级最高,晶粒尺寸最小。试验钢经900℃淬火和180℃回火2小时后的综合力学性能最好。对比发现,经微合金化的G1、G2、G3钢的抗拉强度明显高于G4钢,其中G2钢的强度最高,抗拉强度和屈服强度分别达到1567MPa和1325MPa。四种试验钢低温回火后的延伸率差别不大,均在10%左右。微合金化处理也提高了钢的冲击韧性和硬度。总体上说,V和Nb复合微合金化对提高合金综合力学性能的效果更显著。淬透性测试结果显示,添加微量V的G1钢与母合金G4钢的淬透性相当,而添加了 Nb的G2钢与G3钢的淬透性相当。作为微合金化元素,Nb对提高钢淬透性的作用比V更显著。渗碳处理后,四种试验钢表层碳浓度在0.7%～0.9%之间。添加微量V或Nb的试验钢表层碳浓度和渗碳后表面硬度均高于母合金。此外,微合金化也提高了试验钢的有效渗碳层厚度。四种试验钢的渗碳淬火组织都是由细小针状马氏体和少量的残余奥氏体组成,心部组织都为低碳板条马氏体。微合金化细化了试验钢淬火和回火组织中的马氏体。此外,表层组织中的残余奥氏体百分数也由于微合金化元素的加入而减少,这有利于抗疲劳和耐磨损性能的改善。磨损试验结果显示,V和Nb的微合金化还在一定程度上提高了齿轮钢的耐磨损性能。无论在干磨损还是油润滑磨损条件下,经微合金化处理的试验钢的耐磨损性能均好于母合金。
[Abstract]:20Cr2Ni4 is a kind of common heavy-duty gear steel. Although it is widely used in industrial system at present, it still has some problems, such as poor production and processing performance and short service life, etc. It can not meet the quality requirements of heavy duty gear steel in the transformation of modern industrial industry in China. Based on the chemical composition of 20Cr2Ni4 steel, four kinds of experimental steels, including master alloy (20Cr2Ni4), were prepared by microalloying 20Cr2Ni4 steel with elements V and Nb. The effect of microalloying on grain growth of gear steel was studied. By comparing the microstructure, mechanical properties, hardenability and Carburizing properties of the whole strengthened steel, the effect of microalloying elements on the strengthening of gear steel was studied. The observation of the microstructure of the test steel shows that due to the microalloying of V and Nb, the carbides and nitrides appear in the microstructure of the test steel G1G2G3. In the process of austenitizing, these compounds are not completely dissolved, and they hinder the migration of austenite grain boundaries and refine the austenite grains. Under the experimental conditions of heating temperature 880 鈩，
本文编号：2370172
[Abstract]:20Cr2Ni4 is a kind of common heavy-duty gear steel. Although it is widely used in industrial system at present, it still has some problems, such as poor production and processing performance and short service life, etc. It can not meet the quality requirements of heavy duty gear steel in the transformation of modern industrial industry in China. Based on the chemical composition of 20Cr2Ni4 steel, four kinds of experimental steels, including master alloy (20Cr2Ni4), were prepared by microalloying 20Cr2Ni4 steel with elements V and Nb. The effect of microalloying on grain growth of gear steel was studied. By comparing the microstructure, mechanical properties, hardenability and Carburizing properties of the whole strengthened steel, the effect of microalloying elements on the strengthening of gear steel was studied. The observation of the microstructure of the test steel shows that due to the microalloying of V and Nb, the carbides and nitrides appear in the microstructure of the test steel G1G2G3. In the process of austenitizing, these compounds are not completely dissolved, and they hinder the migration of austenite grain boundaries and refine the austenite grains. Under the experimental conditions of heating temperature 880 鈩，
本文编号：2370172
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