Common stainless steel grades and properties for instruments

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1. 304 stainless steel is one of the austenitic stainless steels with the highest application volume and widest range of uses. It is suitable for manufacturing deep-drawn components, acid transport pipelines, containers, structural parts, and the bodies of various instruments; it can also be used to produce non-magnetic equipment and components for low-temperature applications. It possesses good corrosion resistance, heat resistance, low-temperature strength, and mechanical properties; it is suitable for hot working such as stamping and bending, does not experience hardening due to heat treatment, and is non-magnetic. It is widely used in household items, cabinets, indoor piping, water heaters, boilers, bathtubs, auto parts, medical equipment, building materials, the chemical industry, the food industry, agriculture, and ship components. Differences between 304 stainless steel and ordinary stainless steel: 1) High-temperature resistance. 2) Corrosion resistance. 3) High toughness. 4) Lead content. 2. 304L stainless steel is an ultra-low carbon austenitic stainless steel developed to address the severe intergranular corrosion tendency of 304 stainless steel under certain conditions, which is caused by the precipitation of Cr23C6; its resistance to intergranular corrosion in the sensitized state is significantly better than that of 304 stainless steel. Except for its slightly lower strength, its other properties are the same as those of 321 stainless steel. It is primarily used in corrosion-resistant equipment and components that require welding but cannot undergo solution treatment, and can be used to manufacture various instrument bodies. As a low-carbon version of 304 steel, 304L stainless steel has corrosion resistance similar to that of 304 steel under normal conditions; however, it exhibits excellent resistance to intergranular corrosion after welding or stress relief ； It maintains good corrosion resistance even without heat treatment, and can be used at temperatures ranging from -196°C to 800°C. Applied to field open-air machinery in the chemical, coal, and petroleum industries where high resistance to intergranular corrosion is required, as well as to heat-resistant building materials and parts for which heat treatment is difficult. Differences between 304 stainless steel and 304L stainless steel: 1) The main components of both 304 stainless steel and 304L stainless steel are 18% chromium (Cr) and 8% nickel (Ni) ； Their main difference lies in the fact that 304L stainless steel is a low-carbon version of 304 stainless steel. Under normal conditions, its corrosion resistance is similar to that of 304 stainless steel; however, after welding or stress relief, 304L stainless steel exhibits excellent resistance to intergranular corrosion. 2) In terms of price, 304L stainless steel is more expensive than 304 stainless steel. Being a low-carbon stainless steel, it is primarily suitable for welding processes. When welding, using 304L stainless steel can effectively reduce welding corrosion. 3) Based on hardness standards, 304 stainless steel is superior to 304L stainless steel, as the carbon content directly affects the hardness of stainless steel. There is also the 304H stainless steel series, where H indicates a high carbon content. 3. 316 Stainless Steel: Due to the addition of molybdenum, 316 stainless steel boasts excellent corrosion resistance, resistance to atmospheric corrosion, and high-temperature strength, allowing it to be used in harsh conditions ； Excellent work hardening property (non-magnetic). Equipment used in seawater, as well as production equipment for chemicals, dyes, papermaking, oxalic acid, fertilizers, etc ； Photography, food industry, facilities in coastal areas, ropes, CD rods, bolts, nuts. 4. 316L stainless steel is an ultra-low carbon steel that exhibits excellent resistance to intergranular corrosion in sensitized states; it is suitable for manufacturing welded components and equipment with thick cross-sectional dimensions, such as corrosion-resistant materials used in petrochemical equipment. Mo (2-3%) is added to the steel, resulting in excellent corrosion resistance and high-temperature strength ； 316L has a lower carbon content than 316 and higher high-temperature creep strength. It can be used under harsh conditions, has good work hardening properties, and is non-magnetic. Suitable for seawater equipment, the chemical industry, dyes, papermaking, oxalic acid, fertilizer production equipment, photography, the food industry, and coastal facilities. As the low-carbon version of the 316 steel grade, 316L stainless steel possesses the same properties as 316 steel, in addition to having an excellent resistance to intergranular corrosion. Applied to products with special requirements for resisting intergranular corrosion.