316L stainless steel flat steel is a rectangular section strip made by rolling or forging process, and its material is ultra-low carbon molybdenum containing austenitic stainless steel. It reduces carbon content (C ≤ 0.03%) on the basis of 316, and combines the excellent chloride corrosion resistance endowed by molybdenum element with the welding intergranular corrosion resistance brought by ultra-low carbon. It is an ideal structural material for high demand corrosive environments in marine engineering, chemical equipment, medical devices, and high-end food industry.