Stainless steel must have a minimum chromium content of 10.5% and a maximum carbon content of 1.2%, as defined by European Standard EN 10088-1.
The corrosion resistance of stainless steels can be improved by adding other alloying elements such as nickel, molybdenum, nitrogen and titanium (or niobium). This provides a range of corrosion-resistant stainless steels for a wide range of working conditions, in addition to enhancing other useful properties such as formability, strength and resistance to heat (fire).
Stainless steels cannot be considered corrosion resistant under all operating conditions. Depending on the type of stainless steel, in some cases the passive layer is lost and cannot be reconstructed. In this case, the surface becomes “active” and corrosion occurs.
Stainless steel must be cleaned in order to maintain its good appearance and preserve its corrosion resistance. Stainless steel parts do not corrode under domestic conditions as long as the correct type is selected and normal procedures are followed.
Because of its welding, forming and finishing properties, stainless steel meets the requirements for seamless (sanitary) design, non-stick surfaces, and long-term rigidity of kitchen appliances and cookware.
AISI 430：This is a general purpose steel because of its ductility and good ductility and corrosion resistance properties. It is ideal for furniture and upholstery, as well as for automotive trim and moldings, construction materials, building interiors and panels, kitchen equipment, and other household applications, in addition to a wide range of industrial applications.
304 stainless steel: It has the same range of applications as 430 stainless steel, but due to its chemical properties, when nickel is added, it allows for more complex products (either through forming or welding processes) and has a greater spectrum of resistance to certain agents than 430 stainless steel at certain temperature and pH conditions.
AISI 316. It has the same range of applications as AISI 304, but has better corrosion resistance than AISI 430 and AISI 304 due to the addition of molybdenum in its structure, which allows it to be used in more aggressive environments, such as acid and brine environments. It can be used in architectural decorations, food processing equipment, pharmaceuticals, photography, textiles, laboratories, etc.
Applications.
Type 304 stainless steel is one of the most commonly used grades. 304 and 316 stainless steel are both used in the food and beverage industry. Silos, vats, cheese and fruit cans and wine cans are often made of 304 or 316 stainless steel. type 316 stainless steel is often used in marine applications such as ship fittings. This type of stainless steel is also used to clad the exterior of the Petronas Towers in Malaysia and the Jin Mao Tower in China.
Similarities between 304 and 316.
Both Type 304 and 316 are austenitic stainless steels. This property contributes to their ductility and ability to be easily cast and welded. It also means that these steels are non-magnetic. The chromium in stainless steel also adds a degree of corrosion resistance to the metal. type 304 stainless steel contains 18% chromium, while grade 316 stainless steel contains 17% chromium.
The difference is this.
Molybdenum may also be added to the steel to increase corrosion and pitting resistance. The presence of molybdenum is perhaps the biggest difference between Type 304 and 316 stainless steels. Type 304 stainless steel does not contain trace amounts of molybdenum, while 316 stainless steel contains 2.1% molybdenum.
Type 304 vs. Type 201
When we talk about stainless steel, it is important to know the differences between the two most commonly used types 304 and 201, each has its own chemical composition, as well as advantages and disadvantages, along with specific characteristics such as hardness, corrosion resistance, welding, appearance, etc. Each of these characteristics is what makes each type ideal for a number of projects.
Type 201 is an economical alternative to traditional chromium-nickel stainless steels such as 304. the nickel content of the 201 alloy is very low and is replaced by manganese or nitrogen, which affects corrosion resistance because neither of these elements is as resistant to oxidation as nickel. both 304 and 201 are non-magnetic and their appearance is very similar, which is why many manufacturers use 201.