Definition and characteristics of stainless steel

Stainless steel refers to a high-alloy steel that resists corrosion in air or chemically corrosive media. Stainless steel is used as a short for stainless acid-resistant steel in the professional field. In practical applications, steel that is resistant to weak corrosive media is often referred to as stainless steel, while steel that is resistant to chemical media is referred to as acid-resistant steel. Due to the difference in chemical composition between the two, the former is not necessarily resistant to chemical media corrosion, while the latter is generally rust-resistant. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel. The term [stainless steel" refers not only to a single type of stainless steel, but to more than one hundred industrial stainless steels, each of which has been developed for its specific application.

From the basic elements contained in stainless steel, the Cr content should exceed 10.5% wt (ie, weight ratio), the C content should be less than 1.2% wt, and the iron content should exceed any other elements. From the perspective of metallography, since the stainless steel contains chromium, a very thin chromium film (Cr2O3) is formed on the surface of the stainless steel, thereby isolating the oxygen in the air to achieve the purpose of not rusting. Therefore, chromium is the cornerstone of stainless steel because it forms a protective oxide film. Stainless steel is usually sold in the form of stainless steel hot rolling and cold rolling in the market circulation process. The hot-rolling of stainless steel is based on slabs (mainly continuous casting billets), which are heated to form strips from roughing mills and finishing mills. Cooled by laminar flow to set temperature, coiled into coiled steel coil by coiler, cooled steel coil, according to different needs of users, through different finishing lines (flattening, straightening, crosscutting or slitting) , inspection, weighing, packaging and marking, etc.) processing into steel, flat rolls and slitting steel strip products.

Cold rolling of stainless steel is based on hot-rolled steel coils, which are acid-washed to remove scale and then cold-rolled to obtain stainless steel cold-rolled products. Cold rolled products are hard, 1/4 hard, 1/8 hard, and annealed. Due to the cold rolling of hot rolling through continuous cold deformation, the mechanical properties are relatively poor and the hardness is too high. Usually, in order to meet the performance requirements, the steel coil is annealed after cold rolling, so that the grain structure of the steel is recovered and satisfied. Late user requirements for stretch stamping.