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一前言洛阳拖拉机厂试生产的越野汽车连杆是由45MnB钢制造的,试用中曾发生过连杆断裂事故,究其原因:有结构上的(如圆角半径的大小),有工艺上的(如砂轮磨痕)。有热处理的(如表面脱碳、氧化皮夹杂),也有材质上的(如表面微裂纹)等,它们都不同程度地降低了连杆的疲劳寿命,这方面的问题已有不少专著进行过论述。采用喷丸强化工艺,可在工件表层形成一强化层,消除或改善上述一些因素的影响,有效地提高连杆的疲劳强度,防止了连杆断裂事故的发生,保证了产品质量。本文利用透射电镜研究强化层中的应力状态和组织结构的变化及其对疲劳性能的影响,探索其强化机理,为连杆生产提供有力的依据。
A preface Luoyang tractor factory trial production of off-road car connecting rod is made of 45MnB steel, trial has occurred in the connecting rod rupture, the reason: a structural (such as the radius of the fillet), a process (Such as grinding wheel marks). There are heat treatment (such as surface decarburization, oxide inclusions), but also on the material (such as surface micro-cracks), they all reduce the fatigue life of the connecting rod to varying degrees, the problem has been a lot of monographs Discussion. By shot peening, a strengthening layer can be formed on the surface of the workpiece to eliminate or improve the influence of the above factors, effectively improve the fatigue strength of the connecting rod, prevent the occurrence of connecting rod fracture and ensure the product quality. In this paper, the transmission electron microscope (TEM) was used to study the changes of stress state and microstructure in the reinforced layer and its influence on the fatigue properties. The strengthening mechanism was explored to provide a strong basis for the production of the connecting rod.