关键词: 316L不锈钢, 连铸板坯, 线状缺陷, 冷轧板, 表面裂纹, 工艺改进

Abstract: The metallurgical production flowsheet for 0.3〜4.0 mm cold-rolled sheet of 316L stainless steel is 180t EAF-AOD-LF-200 mm casting slab-hot-rolled 2.5~14.0 mm plate-cold rolling process. The analysis on line scale defects occurred on surface of 316L stainless steel cold-rolled sheet has been carried out by chemical composition analysis, metallography ,scanning microscope and energy spectrum examination on casting slab, hot-rolled coil and cold-rolled sheet. Results show that the surface oscillation mark of casting slab is deeper with depressions and there are depth ≤300 μm micro crack defects ； the surface of hot-rolled plate has line defect and there is larger oxidation area around the line defect ； no large size inclusion is found at the defects of cold-rolled sheet (S content 0.001% and Cr_eq(/Ni_eq = 1.58) , it is obtained that the line scale defects of cold-rolled sheet come from casting stab defects, which are seriously oxidized in heating furnace finally to form the cold-rolled sheet surface line defect. With using the process measures including decreasing slab casting speed from 1. 1 m/min to 1. 0 m/min, reducing overheating extent of liquid from 45℃ to 40℃ , decreasing secondary cooling water rate from 1.0 kg/t to 0.9 kg/t and changing slab grinding wheel from 16# to 20#, the surface defects of cold-rolled sheet decrease markedly.

Key words: 316L Stainless Steel, Casting Slab, Line Defect, Cold-Rolled Sheet, Surface Crack, Process Improvement