What is the difference between stainless steel 304,304L,304H material?
The stainless steel material 304 is the most common grade in industry field.In steel piping systems,there are pipes,fittings,flanges and other products are made from 304 stainless steels.
Grade 304 is an austenitic steel with chromium and nickel as the key elements.Based on these elements 304 steel is very corrosion resistant as well as easy to weld and form.The austenitic structure of the steel means that it can be drawn deeply without intermediate annealing or annealing is not required following the welding of thin sections.
ASTM A403 WP304L Pipe Fitting
They come from different material standards such as ASTM A213, A312, A182 and A403, etc.There are three grade 304 materials in these standards :304, 304L, and 304H. They look similar, but their carbon content is different in chemical composition. (ASTM A403 WP304H pipe fitting)
Among the three, the highest carbon content is 304H, the lowest is 304L, 304 stainless steel carbon content between the two. The higher the carbon content, the worse the corrosion resistance of stainless steel, the more easy to rust.Differences in carbon content can also lead to changes in prices. As we always say, different applications have different requirements.
304, 304L, 304H chemical composition (%):
| Type | C | Mn | P | S | Si | Cr | Ni | N |
| 304 | 0.08 | 2 | 0.045 | 0.03 | 0.75 | 18.00-20.00 | 8.00-10.50 | 0.1 |
| 304L | 0.03 | 2 | 0.045 | 0.03 | 0.75 | 18.00-20.00 | 8.00-12.00 | 0.10 |
| 304H | 0.04-0.10 | 2 | 0.045 | 0.03 | 0.75 | 18.00-20.00 | 8.00-10.50 |
304L is ultra low carbon stainless steel, its carbon content is reduced to less than 0.03%, can avoid intergranular corrosion, theoretically has better stress corrosion resistance than 304, but the effect is not obvious in practical application. Carbon reduction and titanium addition can achieve the same effect, but titanium addition makes 321 stainless steel smelting cost higher, the price is more expensive.
ANSI ASME B16.5 304 RF plain flanges
304H , the H refers to the high temperature, high carbon content makes sure it can meet the high temperature requirements, GB150 (A Chinese standard)requires austenitic steel with 525 degrees or higher, the carbon content of austenitic steel should not be less than 0.04%, its high temperature strength than pure austenite.
304, 304L, 304H mechanical performance:
| Type | T.S（MPa） | Y.S（MPa） | Elongation | Hardness | |
| % | HB | HR | |||
| 304 | ≥515 | ≥205 | ≥40 | ≥201 | ≥92 |
| 304L | ≥485 | ≥170 | ≥40 | ≥201 | ≥92 |
| 304H | ≥515 | ≥205 | ≥40 | ≥201 | ≥92 |
This is the most important difference between the three grades.
We can produce general purpose 304, 304L seamless stainless steel tubes, which is widely used in the oil pipeline, heat exchanger, hydraulic tubing etc, also we produce 304H and 321 seamless stainless steel tubes, which is widely used for boiler tubes.If you want to know more about our products,please feel free to contact us.Email:sales@haihaogroup.com