50CrVA-1弹簧扁钢所制成品板簧自然断裂原因分析

Cause Analysis of the Natural Fracture of Leaf Spring Made of 50CrVA-1 Flat Steel

对影响50CrVA-1弹簧扁钢所制成品板簧片自然断裂的化学成分、脱碳层深度、夹杂级别、硬度和显微组织原因进行了检验分析,综合分析认为造成50CrVA-1成品板簧片自然断裂的主要原因是板簧回火不完全,心部存在一定程度的马氏体组织,而马氏体组织为硬脆组织,在外力作用下极易自然断裂,使得板簧很容易自然断片。通过改进板簧热处理工艺,消除了板簧片心部非正常组织,公司再也没有收到板簧自然断片的质量反馈,取得了良好的经济效益和社会效益。

Factors such as the chemical composition, decarburization depth, inclusion class, hardness and micro- structure affecting the natural fracture of leaf spring made of 50CrVA-1 flat steel were inspected and analyzed. It was considered that the main cause of the fracture was insufficient tempering of the leaf spring, which led to certain amount of martensite staying at the core of the spring. Martensite is a hard brittle structure to break very easily under external impact, causing natural fracture of the leaf spring. After optimizing improvement of the heat treatment process for the leaf spring, the abnormal structure at the core of leaf spring was eliminated and no natural fracture of leaf spring has been reported in users＇ teedeack since, achieving good economic and social effect.