Research on the Causes and Treatment of Weld Zone Fracture in Cold Rolled High Strength Steel Rolling Process

Abstract

In response to the poor quality of laser welding of cold-rolled advanced high-strength steel and the problem of easy fracture at the weld seam during the rolling process, the reasons for the fracture at the weld seam were first analysed using scanning electron microscopy and other equipment, to clarify the fracture characteristics and organizational distribution. Combined with the characterization results of mechanical properties, the reasons for the fracture at the weld seam during the rolling process were elucidated; Then, the influence of welding process on weld quality is studied from four aspects: laser power, welding speed, pre heat power, and post heat power; Based on the above analysis, a typical cold rolled advanced high-strength steel laser welding technology has been developed. By optimizing welding parameters such as welding power, speed, and preheating before and after, the quality of the weld seam and the cup protrusion effect have been ensured. At the same time, a reasonable rolling process optimization plan has been proposed; After applying the research results to the site, the quality of the weld seam has been significantly improved, and the occurrence rate of band breakage at the high-strength steel weld seam has decreased from an average of 3.6% per month to 0.13%. The band breakage defect at the weld seam has been effectively treated.