Stainless steel is a corrosion-resistant alloy consisting of chromium and carbon and other alloying elements in its composition. It is classified into different families according to its microstructure. Based on the configuration of the alloys and usage, Austenitic stainless steel is considered the largest stainless-steel family. Grade 316 is one of the widely used grades in this stainless steel family. It is of high commercial importance. 316-grade stainless steel is known for its 2-3% molybdenum content. It is second in importance to grade 304 in the austenitic stainless steel family.
Type 316 is also known as marine-grade stainless steel. It is because of its ability to resist pitting corrosion. There are various types of 316 stainless steel. Common types include the L, F, N, and H variants. Each of these has slightly different properties and components and is applicable for different purposes. In 316L, the alphabet “L” designates that it has less carbon than 316. Thus, 316L is immune to grain boundary carbide precipitation or sensitization. It is suitable for use in heavy gauge welded components. Grade 316H has a higher carbon content as compared to 316L. It helps increase the strength (especially at temperatures above about 500°C).
You can buy 316 stainless steel tubes if you desire remarkable corrosion resistance and high-temperature strength. The austenitic structure provides it with excellent toughness, even at cryogenic temperatures. The composition of type 316 includes 16% chromium, 10% nickel, and 2% molybdenum. The presence of 2% molybdenum in the alloy provides it with greater resistance to acids and localized corrosion triggered by chloride ions. Hence, it can resist chlorides and other processing chemicals.
Detailed composition of Type 316 (%)
- Carbon: 08 max
- Manganese: 2.00 max
- Phosphorus: 0.045 max.
- Sulfur: 0.03 max
- Silicon: 75 max.
- Chromium: 16.00-18.00
- Nickel: 10.00-14.00
- Molybdenum: 2.00-3.00
- Nitrogen: 0.10 max.
- Iron: Balance
Physical Properties of 316
- Electrical resistivity: 74 microhm-centimeters (20° Celsius)
- Density: 0.799g/cubic centimeter
- Specific Heat: 0.50 kiloJoules/kilogram-Kelvin (0–100° Celsius)
- Thermal conductivity: 16.2 Watts/meter-Kelvin (100° Celsius)
- Modulus of Elasticity (MPa): 193 x 103 in tension
- Melting Range: 2,500–2,550° Fahrenheit (1,371–1,399° Celsius)
Applications of Stainless steel 316
Grade 316 is durable, easy to fabricate, clean, weld friendly, has excellent finish, and offers greater protection from salt spray and brine. Type 316 stainless steel finds use across a wide range of industries for different applications, including
- Food processing equipment
- Chemical and petrochemical equipment
- Laboratory benches & equipment
- Brewery, dairy, and pharmaceutical production equipment
- Coastal architectural panelling
- Boat fittings
- Coastal balustrading
- Heat exchangers
- Chemical transportation containers
- Nuts and bolts
- Mining screens
- Medical implants
- Springs, nuts, bolts, and screws
- Sinks and splashbacks
- Sanitaryware and troughs
- Cutlery and flatware
Three Benefits of Using 316 Stainless Steel
- Marine Applications: Metals can suffer immense damage due to seawater and salt air. Moreover, chlorides like salt can eat away even the toughest metals. Salt can even affect the protective oxide layer formed by chromium in grade 304 stainless steel, which can cause it to rust. Thus, for marine applications or environments in which the metal faces exposure to chlorides, grade 316 stainless steel is ideal. It can remarkably resist salt and chloride pitting corrosion. Pitting corrosionmay occur in grade 304 stainless steel when it is in contact with salt-rich sea breezes and seawater. Grade 316 thus finds extensive use in naval applications and chloride-rich environments.
- Corrosion Resistant Properties: The addition of 2-3% molybdenum in grade 316 stainless steel improves its corrosion-resistant capabilities against similar alloys like 304 stainless-steel. Mo helps reduce pitting from chemical environments and facilitates the use of grade 316 in highly acidic and caustic environments. Grade 316 stainless steel can endure corrosive applications like vapour degreasing. Besides marine applications, it is also suitable for use in pharmaceutical and medical applications.
- Lasting Durability: The toughness and versatility of grade 316 stainless steel make it a valuable metal. It is ideal for custom wire baskets that require long-term durability. Grade 316 enables the baskets to survive continuous exposure to high-impact processes.
Other properties of Grade 316
- Heat Resistance: Type 316 finds use in applications that requires high-temperature oxidation resistance. It can also effectively resist carbide precipitation.
- Hot Working: Almost all types of hot working processes can be performed on grade 316. For hot working, the favorable temperature range is 1149-1260°C. Post-work annealing is recommended to maximize its corrosion resistance.
- Cold Working: Cold working helps increase the strength and hardness of grade 316. It is useful for stamping, heading, and drawing purposes. Post-work annealing helps in bringing down internal stress.
- Fabrication and Welding: Grade 316 is easy to fabricate. Thus, one can easily manufacture drawn stainless parts, such as sinks and saucepans. Manufacturers can use all standard welding techniques on Grade 316. If forging or hammer welding, it is recommended to apply post-work annealing processes to avoid unwarranted corrosion.
Grade 316 stainless steel is highly versatile. It not only shows strong forming and welding characteristics, but manufacturers can easily transform it for use in a wide range of applications. The molybdenum-bearing grade makes grade 316 highly resilient to corrosive abuse, which helps increase its value.