【摘要】 发动机前安装支架是将发动机安装在整车上的连接件,为发动机安全件,材质为热轧钢板,在汽车行驶中承受较大正应力与切向应力,容易出现断裂现象。文章通过对化学成分、物理金相,几何尺寸及加工工艺几方面进行分析,认为焊接工艺对断裂影响最大。焊接时由于加热温度过高,奥氏体晶粒粗大,在冷却时产生粗大的魏氏组织,这些组织易产生裂源,形成裂纹并扩展。因此,要采用适当的焊接方法与焊接温度,减少或消除焊接热影响区,恢复材料原强度与韧性。更多还原

【Abstract】 Engine front mounting bracket is a connecting part which assembling engine on the vehicle. It is a part intended for safety. The material is hot-rolled steel plate which can bear powerful direct stress and tangential force during riding and is easier to be broken. This paper analyzes it in chemical composition, physical metallography, geometrical dimension and manufacturing process, etc. Analysis results show that the welding process is the largest influence factor to fracture. Due to temperature is too high during welding and austenite crystal is thick and big, Widmanstatten organization (thick and big) is produced while the part is cooling. These organizations are easier to form break source and to emerge fracture which will be extended. Therefore, we should take appropriate welding methods and welding temperature, reduce or eliminate area affected by welding heat and recover original strength and ductility.更多还原