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.