302 Stainless Steel (UNS S30200) – Composition, Properties, and Uses
Stainless steel is a popular material for engineers and metalworkers because it has a low carbon content and excellent corrosion resistance. One of the most popular types of stainless steel industry professionals use is type 302, often called “austenitic” stainless steel. Let’s take a closer look at the properties and uses of this valuable alloy.
What is 302 Stainless Steel?
302 SS Alloy, also known as 18-8, gets its name from its chromium and nickel content. 302 is a Stainless Steel 300 Series member and belongs to the Stencil Grade Alloy family, known for being easily machinable and corrosion-resistant. This alloy is a one-of-a-kind compromise with deep drawability and sufficient stretch formability. 302 stainless steel is more stable than 301 stainless steel and exhibits a less noticeable, but still significant, work-hardening response.
What Forms is 302 Stainless Steel Available at Piping Mart?
- Pipes
- Tubes
- Bolts
- Bars
- Fasteners
- Nuts
- Washer
- Screw
- Plates
- Sheets
302 SS Chemical Composition
UNS S30200 contains 17–19% chromium, 8–13% nickel, and 0.15-0.30% carbon. This alloy also contains a small amount of manganese and silicon, which helps to strengthen the metal against corrosion. The chromium content in this alloy gives it excellent corrosion resistance compared to other grades of stainless steel. The nickel content enhances its formability while providing excellent strength against wear and tear.
Element | Content (%) |
Chromium, Cr | 17-19 |
Nickel, Ni | 8 – 10 |
Manganese, Mn | 2 |
Silicon, Si | 1.00 |
Carbon, C | 0.15 |
Sulfur, S | 0.03 |
Phosphorous, P | 0.045 |
302 Stainless Steel Physical Properties
302 Stainless Steel Pipe exhibits excellent toughness, ductility, and ability to retain strength despite exposure to elevated temperatures. Additionally, 302 SS has excellent forming and welding characteristics, making it ideal for complex shapes, deep drawing applications, and other machining requirements. UNS S30200 is also very resistant to stress-corrosion cracking in mildly corrosive environments, meaning it can be used in many different industries, including chemical processing plants and general marine services.
Physical Properties | Metric | English | Comments |
---|---|---|---|
Density | 7.86 g/cc | 0.284 lb/in³ |
UNS S30200 Stainless Steel Mechanical Properties
SS 302 is an austenitic chromium-nickel alloy that offers good corrosion resistance, strength and ductility. Its tensile strength ranges between 100–200 ksi. It offers good formability, weldability and ductility, making it ideal for numerous applications, from food processing equipment to architectural cladding. Its superior strength-to-weight ratio is desirable in high-end engineering applications requiring reliable long-term performance.
Properties | Metric | Imperial |
Tensile strength | 620 MPa | 89900 psi |
Yield strength (@strain 0.200%) | 275 MPa | 39900 psi |
Elastic modulus | 193 GPA | 28000 ksi |
Poisson’s ratio | 0.27-0.30 | 0.27-0.30 |
Elongation at break (in 50 mm) | 55% | 55% |
Hardness, Brinell (converted from Rockwell B hardness) | 147 | 147 |
Hardness, Knoop (converted from Rockwell B hardness) | 164 | 164 |
Hardness, Rockwell B | 85 | 85 |
Hardness, Vickers (converted from Rockwell B hardness) | 147 | 147 |
302 Stainless Steel Equivalent
AMS 5515 | AISI 302 | AMS 5516 | AMS 5636 | AMS 5637 |
AMS 5688 | ASME SA240 | ASTM A167 | ASTM A240 | ASTM A276 |
ASTM A313 | ASTM A314 | ASTM A368 | ASTM A473 | ASTM A478 |
ASTM A479 | ASTM A492 | ASTM A493 | ASTM A511 | ASTM A550 |
ASTM A554 | ASTM A666 | FED QQ-S-763 | FED QQ-S-766 | FED QQ-W-423 |
ASTM A580 | MIL-SPEC MIL-S-862 | SAE 30302 | SAE J230 | SAE J405 |
AMS 5788 | DIN 1.4319 | MIL S-7720 | QQ S763 | QQ S766 |
AISI 302 Stainless Steel Specifications
- AMS 5500 Laminated sheet
- AMS 5515 Sheet / strip Hi Ductility
- AMS 5516 Sheet / strip / plate
- AMS 5600 Laminated sheet
- AMS 5636 Bar Cold Drawn 100ksi
- AMS 5637 Bar Cold Drawn 125ksi
- MIL-S-5059
- MIL-S-22499
- ASTM A240 / ASME SA240
- AISI 302
- BS 970; 302S25 / 302S17
- EN58A / EN58E
- WS 1.4300
- WS 1.4301
- WS 1.4841
- AFNOR Z10CN18-09
- AFNOR Z6CN18-09
- UNS S30302
302 Stainless Steel Maintenance Requirements
Type 302 stainless steel requires minimal maintenance due to its strong corrosion resistance properties. However, it should still be regularly cleaned with a mild detergent or soap to prevent dirt or dust from building up on the surface and causing wear or damage over time. Additionally, suppose the surface becomes scratched or marred during use. In that case, cleaning the area thoroughly before attempting any repairs is important so that no dirt particles become trapped beneath the repair material.
AISI 302 Stainless Steel Uses
Due to its strength, formability, and corrosion resistance, type 302 SS can be used in many applications. It is commonly used in industrial equipment such as pumps, valves, conveyor belts, washers, fasteners, springs, gears, fittings, kitchen utensils, medical tools, automotive parts, etc. Alloy 302 can also be used in outdoor applications where exposure to moisture or other elements could cause other metals to corrode or rust over time. Here are a few examples:
- Spinning
- Stamping
- Wire bending
- Forming into various washers, springs, screens, and cables
- Applications involving pressure in the food and beverage industries
- Applications in sanitary or cryogenic environments
Grade 302 Stainless Steel Corrosion Resistance
AISI 302 is a high-strength, low-corrosion type of stainless steel alloy with excellent corrosion resistance when exposed to mild environmental conditions. It has good mechanical properties, formability, welding characteristics, and cryogenic toughness. It also provides superior resistance to general and localized corrosion in chloride environments, often used in marine applications. Additionally, you can use it for residential piping since its chromium content helps protect against rust damage from neutral water solutions and chlorides.
302 Stainless Steel Hardness
Grade 302 Stainless Steel has a Hardness of 32-38 HRC (Rockwell Hardness Scale). It is relatively soft and ductile for stainless steel but tougher than mild steel, with higher corrosion resistance due to the presence of chromium in its composition. Its mechanical properties can further be enhanced by cold working or heat treatment.
302 Stainless Steel Heat Resistance
302 SS has excellent heat resistance and is often employed for parts exposed to intermittent heating up to 815°C (1500°F). It is also used for cold heading, deep drawing, and applications involving extremely high temperatures and corrosive environments. Additionally, AISI 302 SS offers superior mechanical properties at room and elevated temperatures while offering good ductility in all conditions.
Conclusion:
302 Grade stainless steel is an austenitic chromium-nickel alloy with various uses. It is corrosion-resistant and offers good ductility, magnetism, tensile strength and stress corrosion cracking resistance. It is economical and tough, so it can be used in everything from buckets and tanks to wire mesh for high-temperature environments. As its small carbon content increases its ability to resist intergranular corrosion, technicians may use this material for cryogenic applications where thicker plates would otherwise be too brittle. This alloy’s excellent forming properties make it the ideal choice for fabrication in many industries due to its superior machinability properties. In short, 302 stainless steel’s composition and properties combine to form an alloy that can be widely applied.
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