新型贝氏体钢的连续冷却曲线和接触疲劳性能分析-analysis of continuous cooling curve and contact fatigue performance of new bainitic steel.docx

摘要随着我国铁路提速、重载的发展，轮轨接触应力越来越大，钢轨伤损越来越严重， 影响了行车的平稳性和安全性。开展高强钢轨的研究，对于预防和减缓伤损的出现，延 长钢轨的使用寿命，具有重要意义。贝氏体钢材料具有低碳、高强、高韧的良好综合机 械性能。在许多领域得到了较好的运用。而在钢轨方面的运用研究目前还进行的不够， 为此有必要系统的开展贝氏体材料在钢轨中的运用研究工作，对于我国铁路重载运输的 发展具有很重要的意义。采用膨胀法，结合金相法和硬度法测定了自行研制的新型贝氏体钢的连续冷却曲 线，观察了不同冷速下的室温组织，分析了显微硬度，同时讨论了不同合金元素在连续 冷却过程中的作用。试验结果表明，新型贝氏体钢的贝氏体转变起始温度明显降低，冷 速在 0.011℃/S~0.03℃/S 时出现铁素体组织，冷速在 0.011℃/S~1℃/S 时出现贝氏体组织， 冷速在 0.3℃/S~70℃/S 时出现马氏体组织。由于合金元素的作用，新型贝氏体钢具有良 好的淬透性,其在空冷状态下即可获得贝氏体组织，贝氏体转变区变得扁平。为研究新型贝氏体钢的抗疲劳性能，对普通工艺冶炼和电渣重熔工艺冶炼的新型贝 氏体钢进行了接触疲劳试验。对剥落凹坑进行了金相分析和 SEM 分析。试验结果表明， 试验载荷为 918kg 时，普通工艺冶炼的接触疲劳寿命优于电渣重熔工艺。试验载荷为 1000kg、1183kg、1265kg 时，电渣重熔工艺冶炼的疲劳寿命优于普通工艺。两种工艺的 疲劳破坏形式都有“点蚀”和“剥落”，具体形式与工艺并无明显关系。但电渣重熔工 艺的剥落凹坑要比普通工艺的小而浅。关键词：贝氏体钢；CCT 曲线；接触疲劳;淬透性；电渣重熔工艺AbstractWith the development of the railway’s speed-up and overloading of our country, the railway contact stress become bigger and bigger,the condition of railway became progressively worse,the working stability and security of railway was influenced. It has a great significance to research the high strength steel in preventing and slowing down damage, and prolonging the period of railway. The bainite steel material has good comprehensive mechanical properties as it has low carbon ,high strength and high toughness. It was widely used in many fields. Nowadays the applied research of the railway is not enough yet, it is necessary to systematically carry out the research of bainite materials applied in railway and it is significant to the development of railway heavy-load transportation in China.By the method of dilatometric change , combining with expansion method and hardness method，the CCT curve of the new type of self-manufactured bainitic steel is determed,themicrostructures in different cooling rates are observed and the microhardness and the effect of alloy elements are analysed.The starting temperature of bainite transformation of the new type of bainitic steel are obviously reduced, Ferrite is obtained when the cooling rate ranges between0.011℃/S and 0.03℃/