Commonly used 400 series stainless steel varieties include type 430, which contains 18% chromium, and type 410 and 420 stainless steel, which contain 13% chromium. Among them, type 430 stainless steel is the most used. The characteristics of the 430 type stainless steel model are that it is cheap, has a small thermal expansion coefficient, and has better chloride stress corrosion resistance than the 300 series stainless steel model; however, its disadvantage is that its formability, weldability and tensile strength are lower than those of the 300 series stainless steel model. , therefore, its field of use is limited. Under the same chromium content, the corrosion resistance of 400 series stainless steel varieties is the same as that of 300 series stainless steel varieties in oxidizing media such as atmosphere, fresh water and nitric acid, and generally the corrosion resistance of 400 series stainless steel varieties is better than that of 200 series stainless steel varieties. . The 400 series stainless steel varieties are currently added with trace amounts of niobium, titanium, copper and aluminum elements to improve their deep drawing performance, weldability, corrosion resistance and high temperature resistance, and can partially replace the 300 series stainless steel models. At present, the 400 series stainless steel models after adding the above trace elements include SUS430LX, 430JIL, 444, 445M2, NSS447M1, etc. The United States and Japan widely use these models in automobile exhaust pipes (type 409 and 410L), washing machine inner barrels (type 430), tableware, household appliances, medical equipment, water heaters, roof panels, curtain walls and power plant equipment.