高品质汽车安全带卷簧性能控制实验研究

发布时间：2018-05-28 03:44

  本文选题：汽车卷簧 + 脱碳　； 参考：《安徽工业大学》2014年硕士论文

【摘要】：弹簧钢是一种重要的机械设备基础零件制造材料,现已广泛应用于航空航天、汽车、铁路等诸多领域。由于弹簧钢的工作条件十分苛刻,对弹簧钢的性能要求就十分严格。其中,抗疲劳和抗弹减性减退是影响弹簧钢设计应力的主要因素,与其内在质量(化学成分、纯净度)、表面质量(裂纹、凹坑、脱碳)以及微观组织有密切关系。因此,要求弹簧钢不仅具有较高的强度、良好的塑韧性,而且还要有一定淬透性、较低的脱碳敏感性和良好的加工性能。本文以常用于生产汽车安全带卷簧用弹簧钢Super6和SK5为研究对象,首先研究了两种实验钢的表面脱碳规律,以避免在热轧过程中发生表面脱碳:实验室模拟两种弹簧钢的加热工艺,分析加热温度和保温时间对其脱碳层深度的影响。实验结果表明:弹簧钢Super6的脱碳敏感性要明显高于弹簧钢SK5的。对于弹簧钢Super6可在700℃以上尽量减少加热时间,950℃到1100℃内迅速升温,1100℃以上应尽量减少保温时间,且热卷温度应在700℃以下;对于弹簧钢SK5可在950℃以上尽量减少加热时间,1100℃以上快速升温,热卷温度控制在950℃以下即可。合理制定热处理工艺,以稳定提高两种实验钢的疲劳寿命。利用JMatPro软件模拟了弹簧钢Super6和SK5的CCT曲线。根据JMatPro软件预测结果,设计正交热处理实验方案,并运用极差分析进一步讨论不同热处理工艺对两种实验钢力学性能(屈服强度、抗拉强度和延伸率)的影响规律,以得出两种弹簧钢的最佳热处理工艺。两种实验钢的最佳热处理工艺为:弹簧钢Super6在880℃淬火,保温30 min后油淬,在430℃回火,保温60 min空冷;弹簧钢SK5在850℃淬火,保温30 min后油淬,在400℃回火,保温40 min后空冷。对比两种实验钢回火后的微观组织,分析导致两种弹簧钢疲劳寿命存在差异性的原因。通过对比发现:热处理后,两种实验钢的组织均是回火屈氏体,弹簧钢SK5较弹簧钢Super6的回火屈氏体更细小,碳化物分布更弥散,位错密度也更高;弹簧钢Super6中存在大尺寸的未溶碳氮化物颗粒;弹簧钢Super6中的形变织构和再结晶织构密度均大于弹簧钢SK5中的,特别是{113}110和{331}110织构明显增强。两种弹簧钢微观组织的不同,最终导致两者疲劳性能差异很大。结果表明:经过优化热处理工艺处理过的两种弹簧钢,机械性能均满足要求,其中弹簧钢SK5的疲劳寿命大于40万次,弹簧钢Super6的疲劳寿命大于10万次,均达到了高品质汽车安全带卷簧的疲劳寿命标准。
[Abstract]:Spring steel is an important manufacturing material for basic parts of machinery and equipment, which has been widely used in aerospace, automobile, railway and many other fields. Because the working condition of spring steel is very harsh, the performance requirement of spring steel is very strict. Among them, anti-fatigue and anti-elasticity decrease are the main factors that affect the design stress of spring steel, which is closely related to the internal quality (chemical composition, purity, surface quality (crack, pit, decarburization) and microstructure). Therefore, spring steel not only has high strength, good plastic toughness, but also has certain hardenability, low decarburization sensitivity and good processability. In this paper, the surface decarbonization of two kinds of experimental steels, Super6 and SK5, is studied. In order to avoid surface decarbonization during hot rolling, the heating process of two spring steels was simulated in laboratory, and the effects of heating temperature and holding time on the depth of decarburization layer were analyzed. The experimental results show that the decarburization sensitivity of spring steel Super6 is higher than that of spring steel SK5. For spring steel Super6, the heating time should be reduced as much as possible in the range of 700 鈩，

本文编号：1945150