Type 304 is:
- Austenitic. Type 304 is the most versatile and frequently used chromium nickel stainless steel. It is an all-purpose alloy with a multitude of benefits. It has good corrosion and oxidation resistance, performs well in terms of formability and weldability and is easy to clean. Because this material offers a superb combination of high strength and light weight, about half of the stainless produced in the United States is type 304.
- Used in a variety of applications: Some of the typical uses of grade 304 include appliances, cladding, consumer and industrial products, flanges and valves, handrails, hardware and fasteners, HVAC, kitchen, food and beverage equipment, medical equipment, oil and gas parts, pipes and tubes, plumbing supplies, storage tanks and window frames.
- Able to be processed in many ways: Metal processors and fabricators stamp, form, draw, bend, cut and weld alloy 304 to produce various parts. Cold working will increase strength and hardness.
- Available in many variants: Different levels of carbon and nickel primarily define the different variants of this alloy. Type 304L is a lower carbon variant to type 304 that offers excellent welding characteristics. Type 304H is the higher carbon variant to type 304 and is generally specified when increased mechanical properties are desired. Type 304 is also available with increased levels of nickel, which makes the alloy softer and easier to form often times beneficial for deep drawn processes. Each variant may offer benefits or drawbacks depending on the specific application.
The Chemical Composition and Mechanical Properties of the most common variants of Type 304 are as follows:
| Type 304 | Type 304L | Type 304H | |
|---|---|---|---|
| ASTM A240/A240M (UNS Designation) | S30400 | S30403 | S30409 |
| Chemical Composition | |||
| Chromium | 18.0-20.0% | 18.0-20.0% | 18.0-20.0% |
| Nickel | 8.0-11.0% | 8.0-12.0% | 8.0-10.5% |
| Carbon (max.) | 0.080% | 0.030% | .040-.100% |
| Manganese (max.) | 2.000% | 2.000% | 2.000% |
| Silicon (max.) | 0.750% | 0.750% | 0.750% |
| Sulfur (max.) | 0.030% | 0.030% | 0.030% |
| Phosphorus (max.) | 0.045% | 0.045% | 0.045% |
| Nitrogen (max.) | 0.100% | 0.100% | |
| Mechanical Properties (annealed) | |||
| Tensile (min. psi) | 75,000 | 70,000 | 75,000 |
| Yield (min. psi) | 30,000 | 25,000 | 30,000 |
| Elongation (in 2″, min %) | 40 | 40 | 40 |
| Hardness (max Rb) | 92 | 92 | 92 |
T304, type 304 and grade 304 are interchangeable terms for 304 stainless steel.
T304L, type 304L and grade 304L are interchangeable terms for 304L stainless steel.
T304H, type 304H and grade 304H are interchangeable terms for 304H stainless steel.
