【摘要】 针对开裂的汽车发电机带轮支架，采取宏观微观断口观察、化学成分检测、金相组织分析及显微硬度检测等方式进行分析研究。结果表明：支架断裂位置位于焊点附近，该处焊接质量不良，焊缝处的组织不均，焊点分布不合理，引起应力集中，加上带轮运转过程中对支架施加复杂挤拉交变应力，导致支架端部焊接位置先发生开裂，随后支架中部开裂，断裂机理均属于疲劳断裂。通过优化焊接工艺、调整焊点位置、焊后进行适当回火、减少焊接应力等措施，有效提高支架抗疲劳断裂能力，延长支架的使用寿命。更多还原

【Abstract】 Aiming at the cracked automobile alternator pulley bracket,the macroscopic and microscopic fracture observation,chemical composition detection,metallographic structure analysis and microhardness test were carried out. The results show that the fracture position of the support is near the welding spot. The welding quality in this area is poor. The microstructure of the weld is uneven,and the distribution of the welding spot is unreasonable,which causes stress concentration. In addition,the complex extrusion alternating stress is applied to the support during the operation of the pulley,which leads to the cracking of the welding position at the end of the support first,and then the cracking in the middle of the support. The fracture mechanism is fatigue fracture. By optimizing the welding process,adjusting the position of the welding spot,proper tempering after welding,reducing the welding stress and other measures,the fatigue fracture resistance of the bracket is effectively improved and the service life of the bracket is prolonged.更多还原