316 stainless steel is a premium material known for its exceptional corrosion resistance and strength in harsh environments. As an austenitic alloy, it offers reliable performance in marine, chemical, food processing, and pharmaceutical industries. In this article, we’ll explore what makes 316 stainless steel unique—its chemical composition, physical and thermal properties, applications, and how it compares to other grades like 304, 316L, and 316H.
What is 316 Stainless Steel
316 stainless steel is an iron alloy that contains a number of special elements that make it unique. It belongs to the austenitic stainless steel category, which means that it has a face-centered cubic crystal structure, is non-magnetic, and is highly resistant to corrosion.
In terms of chemical composition, it contains iron, chromium, nickel, molybdenum and carbon, as well as traces of other elements such as manganese, silicon, phosphorus, sulfur and nitrogen. The molybdenum element makes it different from the more familiar 304 stainless steel.
In terms of physical properties, it has a yield strength of 205 MPa, a hardness of 95 Rockwell B, and is non-magnetic. In terms of thermal properties, compared to ferritic steels, 316 stainless steel has a lower thermal conductivity of 16.3 watts per (meter-kelvin). It expands and contracts more significantly than some other materials during temperature changes, with a coefficient of thermal expansion of about 16.5 x 10-⁶/°C between 20°C and 200°C. However, it has a high melting point of 1,370°C to 1,400°C, and good creep resistance to maintain shape stability in high-temperature environments.
When to Use 316 Stainless Steel
316 stainless steel is often referred to as a marine grade alloy because of its excellent resistance to chloride corrosion. Sodium chloride in seawater erodes the iron molecules in the alloy in which it is submerged, triggering pitting corrosion, which is well countered by the molybdenum element contained in 316 stainless steel. It outperforms 304 stainless steel in coastal and marine applications, such as offshore construction and coastal building facades.
Initially, 316 stainless steel was developed for industrial processing in pulp and paper mills. The sulfur-containing compounds in the papermaking process are highly corrosive, and the moisture generated during fiber processing accelerates corrosion.316 stainless steel composite plate was created to solve these problems.
Today, it is used in many applications, like heat exchangers, pharmaceutical equipment, food contact and processing equipment, pasteurization and fermentation tanks. Generally speaking, it is more suitable for applications where there are large amounts of corrosive elements, or where parts have to be immersed in water for long periods of time. For example, in the food processing industry, it is used to make tanks, pipes and containers because it does not react chemically and is easy to clean. In the oil and gas industry, it is used to make pipes, valves, fittings, etc. given its resistance to corrosive fluids and gases.
Common Forms of 316 Stainless Steel
Sheet: Extremely versatile, sheet is cold rolled and can be cut to a variety of sizes in widths ranging from 0.5 mm to 6 mm. It is commonly used for kitchen appliances such as cookware, grills, sinks, countertops, and surface finishes for refrigerators, dishwashers and freezers.
Bar: Also known as round bar, it comes in shapes such as cylindrical or rectangular, and varies in diameter or width. It possesses similar properties to sheet metal but can withstand greater loads and is commonly used in the construction and marine industries.
Thick Plate: similar to thin plate, but 6mm and thicker. Ideal for chemical processing equipment, building structural components, and pressure vessels.
Hot Rolled: Made by heating the material to a temperature point above which its crystal structure changes, then reshaping and cooling. This material is easier to mold and weld, and is more widely used in the automotive, industrial equipment, and construction industries.
Cold drawn: is processed at around room temperature and is usually in the form of a bar with a small diameter. When the surface finish and hardness have high requirements, will choose this processing method, commonly used in the manufacture of precision parts, shafts and fasteners.
Annealed: undergoes an additional treatment process that maintains strength and workability, but also enhances corrosion resistance so that it will not crack or break when reworked and reshaped under pressure.
Advantages of 316 Stainless Steel
316 stainless steel composite plate has many advantages. Compared to 304 stainless steel composite plate, it can maintain higher strength for a longer period of time in a high temperature environment. It has excellent weldability and machinability, good corrosion resistance and outstanding pitting resistance. Its austenitic structure gives it excellent toughness even at low temperatures.
It is resistant to drinking water, has excellent resistance to chlorides and, thanks to the addition of molybdenum, is highly resistant to corrosive chemicals such as acetic, sulfuric and sulfite acids as well as numerous industrial chemicals and solvents. It also reduces the risk of stress corrosion cracking, improves creep resistance, and better resists pitting and crevice corrosion.
316L and 316H Stainless Steel
316L Stainless Steel Sheet is a lower carbon version of 316 Stainless Steel Sheet that minimizes carbide precipitation and is therefore widely used in welding applications. It is well suited for application scenarios in high-temperature, highly corrosive environments and is popular in construction and marine projects. Its low carbon content reduces sensitization effects and is suitable for welded parts of greater thickness (over about 6 mm), helping to maintain toughness and corrosion resistance after welding.
316H stainless steel is a high carbon modified version of 316 alloy plate, developed for high temperature service. It is stronger in high-temperature environments and is commonly used in application scenarios such as structures and pressure vessels in high-temperature environments. However, due to its high carbon content, it is prone to sensitization, resulting in welded joints that are susceptible to corrosion.
Conclusion
In summary, 316 stainless steel stands out as a versatile and durable alloy, ideal for use in corrosive, high-temperature, and high-moisture environments. Whether in offshore structures, industrial processing, or hygienic equipment, 316 offers long-term performance and reliability. By choosing the right grade—316, 316L, or 316H—you ensure optimal results for your specific application, balancing strength, corrosion resistance, and weldability.
