What is stainless steel?
Stainless steel refers to steel that is resistant to weak corrosive media such as air, steam, and water, and chemically corrosive media such as acid, alkali, and salt, also known as stainless acid-resistant steel. In practical applications, the steel that is resistant to weak corrosive media is often called stainless steel, and the steel that is resistant to chemical media corrosion is called 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 stainless. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel. The basic alloying elements of stainless steel include nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the requirements for the structure and properties of stainless steel for various purposes. Stainless steel is easily corroded by chloride ions, because chromium, nickel, and chlorine are isotopes, and the isotopes will exchange and assimilate to form stainless steel corrosion.
Stainless steel is not prone to corrosion, pitting, rusting or wear. Stainless steel is also one of the strongest materials in construction metal materials. Because stainless steel has good corrosion resistance, it can permanently maintain the engineering integrity of structural components. Chromium-containing stainless steel also combines mechanical strength and high elongation, and is easy to process and manufacture components to meet the needs of architects and structural designers.
Common stainless steel grades
Precipitation hardening stainless steel. It has good formability and good weldability, and can be used as an ultra-high-strength material in the nuclear industry, aviation and aerospace industries.
According to the composition, it can be divided into Cr series (400 series), Cr-Ni series (300 series), Cr-Mn-Ni (200 series) 200 series: chromium-manganese-nickel austenitic stainless steel (with 201/202 (202 market) do less))
300 Series: Chromium-Nickel Austenitic Stainless Steels
301: Good ductility, used for molded products. It can also be hardened by mechanical processing. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel.
303: It is easier to cut than 304 by adding a small amount of sulfur and phosphorus.
304: The current commonly used model, namely 18/8 stainless steel. The GB grade is 06Cr19Ni10.
304L: It is a low carbon steel, and the carbon content cannot exceed 0.03%. 00Cr19Ni10 (0Cr18Ni10),
316: After 304, the second most widely used steel grade, mainly used in the food industry, pharmaceutical industry and surgical equipment, adding molybdenum to obtain a special structure that is resistant to corrosion. Because of its better resistance to chloride corrosion than 304, it is also used as “marine steel”. SS316 is usually used in nuclear fuel recovery units. Grade 18/10 stainless steels generally also meet this application level.
316L: Also known as titanium steel, 316L stainless steel. Titanium steel Material grade: 00Cr17Ni14Mo2 with Mo (2~3%) added, excellent pitting corrosion resistance, high temperature resistance and excellent creep resistance.
321: Similar to 304, except that the risk of corrosion of material welds is reduced due to the addition of titanium.
400 Series: Ferritic and martensitic stainless steels.
409: The cheapest model (UK and US), usually used as a car exhaust pipe, is a ferritic stainless steel (chromium steel).
410 420: “Cutter-grade” martensitic steels, the earliest stainless steels similar to Brinell high-chromium steels. Also used in surgical knives, can do very bright.
430: Ferritic stainless steel, decorative, eg for car accessories. Good formability, but poor temperature and corrosion resistance.
Will stainless steel rust?
Stainless steel is not absolutely rust-free, and under certain conditions, stainless steel will still rust. For example, if stainless steel is placed in a humid environment for a long time, it is very easy to rust. In addition, if the stainless steel is stained with vegetable juice, the surface of the stainless steel is also prone to rust. For this reason, in order to keep stainless steel from rusting, it must be cleaned frequently and the surface of stainless steel must be kept dry.