316L stainless steel is a more corrosion-resistant stainless steel developed on the basis of 304 stainless steel. It adds 2% to 3% M element. The addition of potassium element makes 316L stainless steel resistant to dilute sulfuric acid, phosphoric acid, various organic acids, urea corrosion and chloride pitting corrosion. The performance is significantly improved, mainly used in the petroleum and chemical industries, and is widely used in pressure vessels, transportation, metal products, machinery manufacturing, decoration, welded pipes, etc. 231. The surface quality of 316L stainless steel cold-rolled plates is relatively high, and there must be no scratches, Defects such as roughness, pits, and streaks must undergo strict surface quality inspection before leaving the factory.

The production process of 316L stainless steel cold-rolled plate is EAF+AOD+LF+CC+slab grinding+hot rolling+cold rolling. The capacities of EAF, AOD and LF are all 180t, and the continuous casting slab size (thickness×width) is 200mm× Mainly 2040mm, the thickness range of hot-rolled plates is 2.5-14.0mm, and the thickness range of cold-rolled plates is 0.3-4.0mm. The type of defect rate on the surface of cold-rolled stainless steel plates with the highest defect rate is linear defects. This defect often causes the surface of cold-rolled stainless steel plates to be unqualified, which has a great impact on product quality and yield rate.

(1) Through the morphology and energy spectrum analysis of surface defects of 316L stainless steel continuous casting billet, hot-rolled black coil surface defects and surface linear defects of cold-rolled plates, it was found that the linear defects of cold-rolled plates originate from the continuous casting billet.

(2) The micro-cracks on the surface of the continuous caster are heated at high temperature for a long time in the heating furnace, forming a large area of ​​oxidation, which is inherited to the surface of the cold-rolled plate after rolling, resulting in linear defects on the surface of the cold-rolled plate.

(3) Defects such as slag pits and micro-cracks on the surface of the continuous casting billet can be ensured by fine grinding with a 20° grinding wheel to ensure the surface quality of the cold-rolled plate.

(4) By improving the continuous casting production process parameters, the surface quality of 316L stainless steel continuous casting has been greatly improved, and the surface quality of cold-rolled stainless steel plates has been greatly improved.