激光微造型球墨铸铁表面干摩擦性能研究

发布时间：2018-11-12 18:13

【摘要】：基于激光喷丸的力学效应在材料表面制备具有一定形貌参数的微造型阵列,能够改善其摩擦磨损性能,因此在摩擦磨损领域得到了广泛的研究与应用。本文以球墨铸铁材料为研究对象,利用激光喷丸加工技术,在试样表面制备具有一定几何参数和形貌的微造型阵列,并对微造型后的试样表面进行相应的力学性能测试,最后通过干摩擦磨损试验和往复滑动磨损过程数值模拟,综合分析了微造型几何参数和形貌对球墨铸铁表面减摩耐磨性能的影响机理。主要工作包括:(1)基于激光喷丸技术相关理论,探讨了激光喷丸处理对球墨铸铁表面微观组织及其力学性能的影响机理;通过调节激光喷丸过程中的激光能量和控制平台运动速度,加工出具有不同深径比和中心距的微凹坑阵列,同时根据力学性能测试结果,得到了激光喷丸能量与微造型表面显微硬度和残余应力之间的对应关系。(2)通过开展干摩擦磨损试验,分析了不同微造型参数(深径比、凹坑中心距)对球墨铸铁试样表面摩擦磨损特性的影响规律,研究发现:微凹坑深径比0.052、中心距2 mm的微造型试样表面具有最佳的干摩擦磨损性能;最后根据干摩擦磨损理论以及磨痕形貌观测图,进一步分析了微造型试样表面的减摩耐磨机理。(3)通过对比分析未造型与微造型接触表面在往复滑动磨损过程中的等效应力分布和温度分布的数值模拟,结果发现未造型模型接触面的应力集中区域显著大于微造型模型接触表面,微造型模型接触表面平均等效应力值明显小于未造型表面,应力集中程度得到明显改善;未造型模型接触区的温升最大值高于微造型表面,且未造型模型在滑动磨损过程中,接触面的温升区域较大,微造型模型接触表面的温度要普遍低于未造型接触表面,且不会出现大面积温升区域,表面温度分布状况得以改善。
[Abstract]:Based on the mechanical effect of laser shot peening, micro-molding arrays with certain morphologic parameters can improve the friction and wear properties of the materials, so they have been widely studied and applied in the field of friction and wear. In this paper, the nodular cast iron was used as the research object, and the micro-molding array with certain geometric parameters and morphologies was prepared on the surface of the sample by laser shot peening technology, and the corresponding mechanical properties of the micro-moulded sample surface were tested. Finally, through dry friction and wear test and numerical simulation of reciprocating sliding wear process, the influence mechanism of geometric parameters and morphology of micro-molding on friction and wear resistance of nodular cast iron surface is analyzed synthetically. The main works are as follows: (1) based on the theory of laser shot peening, the influence mechanism of laser shot peening on the microstructure and mechanical properties of nodular cast iron surface is discussed. By adjusting the laser energy during shot peening and controlling the moving speed of the platform, the microcrater array with different aspect ratio and center distance is fabricated. The relationship between laser shot peening energy and microhardness and residual stress of micro-moulding surface is obtained. (2) through dry friction and wear test, different parameters of micro-molding (ratio of depth to diameter) are analyzed. The effect of pit center distance on the surface friction and wear characteristics of ductile iron samples was studied. It was found that the surface of micro shaped specimens with the ratio of depth to diameter of micropits 0.052 and center distance of 2 mm had the best dry friction and wear properties. Finally, according to the dry friction and wear theory and wear trace morphology observation, The mechanism of friction reduction and wear resistance on the surface of micro-molding sample is further analyzed. (3) the numerical simulation of equivalent stress distribution and temperature distribution of unmolded and micro-molded contact surfaces during reciprocating sliding wear is analyzed. The results show that the stress concentration area of the contact surface of the unmolded model is significantly larger than that of the contact surface of the micro-modeling model, and the average equal-effect force value of the contact surface of the micro-modeling model is obviously lower than that of the unmolded surface, and the degree of stress concentration is obviously improved. The maximum temperature rise in the contact area of the unmolded model is higher than that of the micro-modeling surface, and the temperature rise area of the contact surface is larger in the sliding wear process of the unmolded model, and the temperature of the contact surface of the micro-modeling model is generally lower than that of the unmolded contact surface. And there will be no large area of temperature rise, surface temperature distribution can be improved.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG143.5;TG668

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