Stainless steel is an alloy containing at least 10% chromium, which provides its signature corrosion resistance. The chromium reacts with oxygen to form a protective oxide layer on the metal’s surface, safeguarding it against rust and degradation. Among the various grades, 316 stainless steel stands out for its excellent resistance to corrosion, making it ideal for industries like chemical plants, refineries, and marine. Types 1.4401 and 1.4404, also known as grades 316 and 316L, are widely used variations.
This blog explores the grades of 316 stainless steel in detail, covering its types, key properties, and industrial applications.
What is 316 stainless steel?
316 stainless steel is a premium alloy known for its exceptional corrosion resistance, durability,. It belongs to the austenitic family of stainless steels. SS 316 material contains molybdenum, which significantly enhances its resistance to pitting and crevice corrosion, especially in chloride-rich environments.
Grades of Stainless Steel 316
- 316L Stainless Steel (Low Carbon)
316L is a low-carbon version of 316 stainless steel, designed to minimize carbide precipitation during welding. This property makes it ideal for heavy-gauge welded components over 6mm thick. It provides the same corrosion resistance as standard 316 while reducing the risk of sensitization. - 316H Stainless Steel (High Carbon)
316H is the high-carbon variant of 316, developed for applications requiring enhanced thermal stability and resistance to creep at elevated temperatures. It is commonly used in high-temperature environments like boilers, heat exchangers, and pressure vessels. - 316Ti Stainless Steel (Stabilized with Titanium)
316Ti is stabilized with a small addition of titanium (approximately 0.5%) to improve resistance to intergranular corrosion. This grade performs exceptionally well in high-temperature environments above 800°C and is widely used in heat exchangers, furnace parts, and exhaust systems.
Corrosion Resistance of Stainless Steel 316
Stainless steel 316 offers excellent corrosion resistance and is known as “marine grade” stainless steel, outperforming grade 304. However, it is not fully resistant to warm seawater, where chloride-rich conditions can cause pitting and crevice corrosion. It tolerates chlorides up to 1000 mg/L in potable water at ambient temperatures, reducing to 500 mg/L at 60°C. Despite susceptibility to stress corrosion cracking above 60°C and surface staining in crevices.
Heat Resistance of 316 Stainless Steel
316 stainless steel doesn’t harden through heat treatment but is enhanced through annealing at 1010°C to 1120°C, followed by rapid cooling. This process relieves stresses and restores corrosion resistance. For resistance to intergranular corrosion, grade 316L is used, while grade 316H, with higher carbon content, is preferred for high-strength, elevated-temperature applications. While 316 offers excellent oxidation resistance up to 925°C, prolonged use between 425°C to 860°C is not recommended for water-corrosion resistance.
Welding of Stainless Steel 316
SS 316 stainless steel offers excellent weldability through various fusion welding methods, both with and without filler metals. The recommended filler rods and electrodes for welding SS 316 and 316L are identical to the base metal, ensuring strong and durable joints. While welding heavy sections of SS 316 may require post-weld annealing to maintain optimal corrosion resistance, this is not necessary for SS 316L due to its low carbon content. For heavy section welds, SS 316Ti, which contains titanium for stabilization, can be used as an alternative to SS 316. However, oxyacetylene welding is not suitable for joining SS 316 stainless steel. The material is pre-qualified for welding under standards like AS 1554.6 when using appropriate rods or electrodes.
Cold Working of 316 Stainless Steel
Stainless steel 316 is easy to shape into different parts using brake or roll forming. It’s also good for processes like stamping, heading, and drawing. However, after these processes, annealing (heating and cooling) is recommended to reduce internal stresses in the material. Cold working, which involves shaping the steel at room temperature, makes 316 stainless steel stronger and harder.
Hot Working of Stainless Steel 316
Stainless steel 316 can be easily shaped using all common hot working methods. However, it should not be worked below 927°C. The best temperature range for hot working is between 1149°C and 1260°C. After hot working, it’s recommended to anneal the steel to restore its corrosion resistance.
316 Stainless Steel Heat Treatment
316 stainless steel cannot be hardened by heat treatment. Instead, it can undergo a process called solution annealing, where the material is heated to a temperature between 1010°C and 1120°C, then rapidly cooled to prevent the formation of chromium carbides.
Machinability of 316 Stainless Steel
316 stainless steel is easy to machine with the right techniques. Keep cutting tools sharp to avoid hardening the material. Make light cuts, deep enough to prevent the tool from just skimming the surface. Use chip breakers to clear debris, and always apply plenty of coolants and lubricants since the material can heat up quickly during machining.
SS 316 Chemical Composition
|
Element |
316 |
316L |
316H |
316Ti |
|
Carbon (C) |
0.0–0.07 |
0.0–0.03 |
0.04–0.08 |
0.0–0.08 |
|
Manganese (Mn) |
0.0–2.0 |
0.0–2.0 |
0.0–2.0 |
0.0–2.0 |
|
Silicon (Si) |
0.0–1.0 |
0.0–1.0 |
0.0–1.0 |
0.0–1.0 |
|
Phosphorus (P) |
0.0–0.05 |
0.0–0.05 |
0.0–0.04 |
0.0–0.05 |
|
Sulfur (S) |
0.0–0.02 |
0.0–0.02 |
0.0–0.02 |
0.0–0.03 |
|
Chromium (Cr) |
16.50–18.50 |
16.50–18.50 |
16.50–18.50 |
16.50–18.50 |
|
Molybdenum (Mo) |
2.00–2.50 |
2.00–2.50 |
2.00–2.50 |
2.00–2.50 |
|
Nickel (Ni) |
10.00–13.00 |
10.00–13.00 |
10.00–13.00 |
10.50–14.00 |
|
Titanium (Ti) |
– |
– |
– |
0.40–0.70 |
|
Iron (Fe) |
Balance |
Balance |
Balance |
Balance |
Stainless 316 Material Properties
Stainless steel 316 offers excellent mechanical and physical properties, including high tensile and yield strength, excellent corrosion resistance, and good machinability. These properties are primarily specified for flat-rolled products like plate, sheet, and coil under ASTM A240/A240M. Similar specifications apply to other forms, such as pipes and bars, under their respective standards, with minor variations in property details.
Mechanical Properties
| Grade | Tensile Str (MPa) min | Yield Str 0.2% Proof (MPa) min | Elong (% in 50 mm) min | Hardness | |
| Rockwell B (HR B) max | Brinell (HB) max | ||||
| 316 | 515 | 205 | 40 | 95 | 217 |
| 316L | 485 | 170 | 40 | 95 | 217 |
| 316H | 515 | 205 | 40 | 95 | 217 |
Physical Properties
|
Property |
Value |
|
Density |
8.00 g/cm3 |
|
Melting Point |
1375-1400°C |
|
Modulus of Elasticity |
193 GPa |
|
Electrical Resistivity |
0.074×10-6 Ω.m |
|
Thermal Conductivity |
16.3 W/m.K at 100°C |
|
Thermal Expansion |
15.9×10-6 /K at 100°C |
Applications of 316 Stainless Steel Grades
|
Grade |
Applications |
|
316 Stainless Steel |
– Marine: Boat fittings, underwater pipelines. |
|
– Chemical: Tanks, heat exchangers. |
|
|
– Food & Beverage: Processing and storage equipment. |
|
|
– Medical: Surgical tools and medical devices. |
|
|
316L Stainless Steel |
– Welding: Oil pipelines, storage tanks. |
|
– Pharmaceutical: Corrosion-resistant equipment. |
|
|
– Cryogenic: Vessels and piping for low-temperature applications. |
|
|
316Ti Stainless Steel |
– Heat-Intensive: Chemical reactors and kilns. |
|
– Exhaust Systems: Automotive and industrial exhaust components. |
|
|
– Aerospace: Heat-resistant parts for aircraft. |
Conclusion
In conclusion, Kalpataru Piping Solutions is a trusted supplier of high-quality 316, 316L, and 316Ti stainless steel products, catering to various industrial needs. As reliable 316 stainless steel suppliers, we ensure superior materials that meet the highest standards for performance and durability. Whether you’re looking for stainless steel 316 for specific applications or require expert guidance, we are here to guide you.
Contact us today to learn more about our range of stainless steel 316 products to meet your requirements.
FAQs
What is the cost of 316 stainless steel?
The cost of 316 stainless steel depends on various factors such as the supplier, quantity, and specific requirements like size and grade. It’s best to request a quote from suppliers for accurate pricing.
Does grade 316 stainless steel rust?
While highly resistant to rust due to molybdenum, grade 316 stainless steel can still show signs of corrosion in harsh marine conditions.
Which grade is better, 304 or 316 stainless steel?
Grade 316 is better for highly corrosive environments due to its added molybdenum, offering superior resistance compared to grade 304.
Is 316 stainless steel worth the extra cost over 304?
Yes, for environments with high acidity or salinity, the enhanced corrosion resistance of 316 justifies its higher cost.
What is the grade of ASTM 316?
ASTM A240 Type 316 is a stainless steel alloy containing chromium, nickel, molybdenum, and trace elements, designed for superior corrosion resistance.
What is 316 stainless steel grade?
Grade 316 is an austenitic stainless steel with molybdenum, offering better corrosion resistance than 304, especially in marine and chemical environments.
What is the grade of 316 steel?
316 and 316L (1.4401 and 1.4404) are austenitic stainless steels with molybdenum, providing excellent corrosion resistance, second only to 304 in commercial usage.
