Fracture analysis for longitudinal weld of rear cross beam
LI Rong-feng 1，TAN Lu 2， MO Jia-hao 1， ZHANG Shu-yan 1，3
1.Center of Excellence for Advanced Materials， Dongguan 523808， China； 2. Gestamp Metal Forming（Wuhan） Ltd.， Wuhan 430073， China； 3.Songshan Lake Laboratory for Material Science， Dongguan 523808， China
Abstract： Aiming at the longitudinal cracking in the welded seam of rear cross beam of one car， the methods including macroscopic observation， metallographic examination and scanning electron microscope were employed. The causes for cracking of weld were analyzed using CP-800 high strength steel with thickness of 2 mm. SEM characterization results showed that the cracks originated from Cr oxide as well as its composite oxides with Al， Si， Ca and Mn. Moreover， the formation of fatigue striations was observed. It indicated that the cracking was formed due to the rapid expansion of fatigue cracks when they were expanded to critical dimensions under the action of external loads.
2020, Vol. 38 
