Stainless Steel - Grade 308 (UNS S30800)
Stainless Steel is one of the most prominent materials used in various industries. Its increasing popularity and reliable usage across various industries have resulted in a sudden increase in its demand. Owing to different requirements of different industries various variations were done in terms of stainless steel chemical composition, resulting in different grades of stainless steel.
In this article below, we will be reading about one such unique stainless steel; Grade 308.
About Grade 308 Stainless Steel
Stainless Steel Grade 308 or UNS S30800 is austenitic steel composed of a good amount of chromium, nickel and manganese along with other metals. The rich constitute of Grade 308 provides it with high corrosion resistance, good weldability and formability. It also has high mechanical properties at varied temperatures. It is largely used in metalworking applications like kitchenware, medical equipment, etc.
AISI 308 Chemical Composition
It is the chemical composition of stainless steel that provides it with its unique characteristics. With a good amount of chromium and nickel, SS Grade 308 is highly corrosion-resistant. Let us have a detailed look at the chemical composition of Grade 308 stainless steel before moving on to its other properties.
| Element | Percentage |
| Iron, Fe | 66% |
| Chromium, Cr | 20% |
| Nickel, Ni | 11% |
| Manganese, Mn | 2.0% |
| Silicon, Si | 1.0% |
| Carbon, C | 0.080% |
| Phosphorous, P | 0.045% |
| Sulfur, S | 0.030% |
Physical Properties of Stainless Steel Grade 308
Density affects the properties of steel, such as strength, durability, malleability, ductility, electrical conductivity, heat capacity, thermal expansion rate, etc. Hence it becomes crucial to understand its physical properties including density, before finalizing it for your application. Here is the physical property of stainless steel grade 308 to help you make a wise decision.
| Property | Value |
| Density | 8 g/cm³ |
Mechanical Properties of Stainless Steel Grade 308
Like the physical properties, the mechanical properties of stainless steel also play a crucial role in establishing its suitability for various applications. Here is a sneak peek into the mechanical properties of stainless steel.
| Property | Value |
| Tensile strength | 585 MPa |
| Yield strength (@ strain 0.200%) | 240 MPa |
| Izod impact | 135–165 J |
| Charpy impact | 135 J |
| Elastic modulus | 193 GPa |
| Poisson's ratio | 0.27–0.30 |
| Elongation at break (in 50 mm) | 50% |
| Hardness, Brinell | 139 |
| Hardness, Knoop (converted from Rockwell B) | 155 |
| Hardness, Rockwell B (converted) | 80 |
| Hardness, Vickers (converted from Rockwell B) | 153 |
Thermal Properties of Stainless Steel Grade 308
The thermal properties of stainless steel determine its nature during extreme temperatures. Let us have a quick look at the thermal properties of Grade 308.
| Property | Value |
| Thermal expansion coefficient (@ 0–100°C/32–212°F) | 17.3 µm/m°C |
| Thermal conductivity (@ 0–100°C/32–212°F) | 15.2 W/mK |
Applications of Stainless Steel Grade 308
Grade 308 finds its extensive usage in applications where corrosion resistance is critical. Also being highly weldable, it is commonly used for welding to ensure a strong, durable weld.
- Kitchen appliances,
- structural supports,
- Chemical processing equipment,
- Food processing,
- Medical equipment manufacturing industry
Frequently Asked Questions
Q1. What is 308 stainless steel used for?
308 stainless steel is mainly used as a welding filler metal for joining 304-series stainless steels, and in kitchenware, structural supports, chemical processing equipment, food processing units, and medical equipment manufacturing.
Q2. What is the difference between 308 and 304 stainless steel?
308 stainless steel has a slightly higher chromium and nickel content than 304, which improves its performance as a welding filler and gives it marginally better corrosion resistance. 304 is more commonly used as the base material itself, while 308 is typically chosen for welding 304 components.
Q3. Is 308 stainless steel magnetic?
No. Like other austenitic stainless steels, 308 is non-magnetic in its annealed condition due to its face-centered cubic crystal structure.
Q4. What is the UNS number for 308 stainless steel?
The UNS designation for 308 stainless steel is S30800.