新型起重机制动轮的组织性能及表面应力研究

发布时间：2018-06-07 07:41

  本文选题：制动轮 + 裂纹　； 参考：《大连理工大学》2014年硕士论文

【摘要】：制动轮是起重机类产品的重要零部件。大吨位起重机服役一段时间后,常会在制动轮表面出现裂纹,裂纹的出现会导致制动轮的破坏,使起重机产生安全隐患。研究新型起重机制动轮材料的组织性能及制动轮表面应力状态,对分析制动轮表面裂纹缺陷的产生,有效提高制动轮的使用寿命具有重要的意义。 本文以研制新型高性能起重机用制动轮为目标,主要开展了三方面的研究内容：1.在原制动轮材料的基础上,通过添加合金元素,提高材料的热疲劳性能和综合力学性能指标；2.通过三种新型合金试样在不同热处理工艺条件下的金相组织和力学性能分析,初步确定新型制动轮合金的化学成份和热处理工艺；3.通过制动轮表面残余应力的测试,分析和探讨残余应力对制动轮表面发生裂纹缺陷的影响。研究结果表明： 对于ZG340A、ZG340B和ZG35CrMnSi,通过优化热处理工艺可以得到满足制动轮服役要求的使用性能。由于ZG340A和ZG35CrMnSi合金均具有良好的综合使用性能,应优先考虑选择。这两种合金比较合理的热处理工艺分别为ZG340A:870℃正火+550℃回火；ZG35CrMnSi:860℃淬火+600℃回火。 ZG340A合金(正火十回火)具有良好的综合性能,降低了其对表面缺陷、夹杂以及氧化物等潜在疲劳裂纹源的敏感性,同时其微观组织特性有利于缓解裂纹尖端处的应力集中,阻止疲劳裂纹的扩展；ZG340A合金在高温下(500℃)的磨损表面没有发生严重的氧化现象,由于迁移的Ni、r等元素以氧化物的形式残留在磨损表面,使磨损很快进入稳态阶段；ZG340A合金的基体,易于形成磨屑迁移,而迁移磨屑滞留在磨损表面,起到一定的承载和稳定磨损的作用,因此具有较好的抗磨损性能。 35CrMnSi合金具有较高的断裂韧性和高温强度,其磨损机制主要为显微剥落。其高温磨损的显微剥落呈现比较均匀的状态,几乎没有出现局部的宏观剥落深坑,35CrMnSi合金也同样具有良好的抗磨损性能。 制动轮表面残余应力不大,实测的最大应力值小于62.2MPa,而且分布比较均匀。在进行粗加工和精加工后,表面残余应力还会进一步降低；制动轮服役时,由于表面的反复挤压,而使表面应力得到进一步释放,残余应力会降到更低值。因此,残余应力对制动轮服役时表面裂纹的产生不会起主要的作用,合金成分、冶金质量、热处理工艺和服役时周期变化的接触力作用是导致制动轮表面产生裂纹的主要原因。
[Abstract]:Brake wheel is an important part of crane products. After the large tonnage crane has been in service for a period of time, cracks often appear on the surface of the brake wheel, which will lead to the failure of the brake wheel and make the crane have a hidden danger of safety. The study of the structure and properties of the brake wheel material and the stress state on the surface of the brake wheel is of great significance to the analysis of the surface crack defects of the brake wheel and the effective improvement of the service life of the brake wheel. Aiming at the development of a new type of brake wheel for high performance crane, this paper mainly develops three aspects of research contents: 1. On the basis of the original brake wheel material, the thermal fatigue properties and the comprehensive mechanical properties of the material were improved by adding alloying elements. Based on the analysis of metallographic structure and mechanical properties of three new alloy samples under different heat treatment conditions, the chemical composition and heat treatment process of the new type brake wheel alloy are preliminarily determined. By measuring the residual stress on the surface of the brake wheel, the influence of the residual stress on the crack on the surface of the brake wheel is analyzed and discussed. The results show that: For ZG340A, ZG340B and ZG35CrMnSi, the service performance of brake wheel can be obtained by optimizing heat treatment process. As both ZG340A and ZG35CrMnSi alloys have good comprehensive performance, preference should be given to their selection. The reasonable heat treatment process of the two alloys is ZG340A:870 鈩，

本文编号：1990390