铝合金左悬置支架断裂失效分析

通过金相显微镜、扫描电子显微镜、能谱仪、布氏硬度计和直读光谱仪对某车型坏路试验过程中断裂的铝合金左悬置支架进行失效分析。结果表明,零件的失效模式为疲劳断裂,试验过程中以夹杂物为主的铸造缺陷作为裂纹源发生疲劳开裂并扩展,裂纹扩展至零件剩余截面使其不能承受试验过程中的载荷,进而发生瞬时过载断裂。测试显示,铝合金左悬置支架的化学成分与布氏硬度检验结果均符合设计标准要求。

Effects of Rolling Parameters on Texture and Formability of High Strength Ultra-Low Carbon BH Steel

The effects of hot rolling and cold rolling parameters on texture and r （ plastic strain ratio ） value of high strength ultra low carbon bake hardening （ ULC-BH ） steels are studied with orientation distribution function （ ODF ） structural analysis method.After hot rolling , the high strength ULC-BH steel sheet has weakγ-fiber with uniform orientation distributions , and weakα-fiber , of which { 445 } component forms a high intensity peak at coiling temperature of 750℃.After cold rolling , both { 111 } -{ 111 } intensity on theγ-fiber and{ 111 -}{ 112 } intensity on theα-fiber enhanced.As a result of substitutional solute elements Mn and P being added to the steel , strong { 112 } deformation texture component is observed onα-fiber , especially at 80%cold rolling reduction , and this leads to the strong { 111 } recrystallization texture after annealing.The increase of cold rolling reduction shifts the maximum intensity on theγ-fiber from { 111 } to { 111 } .After annea-ling , a very strongγ-fiber is obtained , with intensity peak at { 111 } component when cold rolling reduction reaches 80%.Increasing coiling temperature and cold rolling reduction improveγ-fiber intensity and r value , resulting in good deep drawability.

悬置双头螺柱失效分析

某车型的左悬置与支架连接的双头螺柱在试验过程中发生断裂,其材料是42Cr Mo,强度等级为10.9级,依次对其进行宏观形貌分析、微观形貌分析、金相检查、化学成分分析和力学性能检查。结果显示,双头螺柱在长期交变应力作用下产生了微裂纹,最终发生疲劳断裂。断裂原因是螺柱生产工艺顺序不当,先加工螺纹后进行调质处理使牙底的疲劳强度不足。