Cause Analysis of Fine Longitudinal Stripe Defect on Ferritic Rolled IF Steel

In the development of IF steel in ferrite rolling process,the fine longitudinal stripe defects had been observed on the surface of cold rolled product,and the defect is different from the conventional rolling process.In order to find the reason of causing this kind of defects and thereby solve the problem,extensive experimental analysis had been done,focusing on the microstructure and mechanical properties of the product,at the same time surface roughness measurement had been carried out on a TR200 roughness tester.Microstructural observation show there is no obvious differences in grain size of hot rolled plate,implies that fine longitudinal stripe defects of IF ferrite rolling products should be formed during cold rolling and annealing process,and might be due to the low yield strength of the finished coil. Therefore,the annealing temperature has been reduced by 20 ℃,while the hot rolling process had been optimized.The mechanics properties and microstructure of resulted IF steel coil had been improved accordingly,while the fine longitudinal stripe defects had been eliminated.