Cracking Analysis of Automobile Rim Butt Welding

The crack of automobile roll forming rim was analyzed by means of the chemical composition analysis,macrocosmic and microcosmic examination,the experimental results show that the oxide inclusion in fusion areas,widmanstatten structure,and free cementite producing along the grain edge are weak mechanical property in joint. The micro-crack initiated near the beat-affective zone. Under the above factors,the rim was cracking during the expansion.