Strip Breakage Analysis on Flash Welding Joints of Pickling Line-tandem Cold Rolling Mill

Frequent strip breakage reasons for soft Stb35L thin steel strip flash welding joints of pickling line-tandem cold rolling mill was investigated by macro analysis, mechanical properties test, metallographic examination and fracture analysis. The results show that the head and end sheet shape of the hot rolling material strip was bad, and it wasn’t leveled or cut before welding, which caused lap weld at part zone of the flash welding joints. Then in the cold rolling process, folds and cracks formed at the lap weld position, and the strip breakage happened with the constant extension of the folds and cracks. The other reason for the strip cracking and breakage was that there were chains oxide in the flash weld.