Question: What is 304H material? What is the difference between it and 304L?

304H is just 304; it’s the case that, on top of the properties of 304, higher requirements are placed on the hardenability of the material. 304L has a lower carbon content than 304. Please correct me if I’m wrong; feedback is welcome!!!

304H is the 304 high version with a higher carbon content; 304 is the standard version. 304L is the 304 low version with a lower carbon content

Oh, thanks for the advice from the expert. :victory:

The equivalent Chinese steel grades are 304H 0Cr19Ni9 (0Cr18Ni9), 304L 00Cr19Ni10 (00Cr18Ni10)

Compared to 304 and 304L, 304H differs mainly in its carbon content. 304H (0.04–0.10), 304 (0.08), 304L (0.030); the values in parentheses represent the carbon content. 304 corresponds to China’s 0Cr18Ni9 stainless steel, while 304L corresponds to China’s 0Cr18Ni10. There is little difference in the content of other elements. Features of 304H: It is a stainless heat-resistant steel with good formability and weldability, corrosion resistance, high permanent strength and structural stability, as well as excellent cold deformation capacity. It can be used at temperatures up to 650°C, with an oxidation resistance up to 850°C. 304 is a general-purpose stainless steel that is widely used in the manufacture of equipment and components that require good overall properties such as corrosion resistance and formability. The 304L variant has better weldability and formability due to its lower carbon content. Mechanical properties of 304, 304L, and 304H: Type, tensile strength, yield strength, elongation at 50 mm, hardness, cold bending – (MPa), (MPa), %, Brinell, Rockwell. 304: ≥515, ≥205, ≥40, ≥201, ≥92; no requirement specified. 304L: ≥485, ≥170, ≥40, ≥201, ≥92; no requirement specified. 304H: ≥515, ≥205, ≥40, ≥201, ≥92; no requirement specified. The values above are experimental data. 　　Note: The yield strength is the 0.2% yield strength. Furthermore, clause 4.1.6 of China’s pressure vessel standard GB150-1998 stipulates that when austenitic stainless steel is used at temperatures above 525°C, its carbon content must be at least 0.04%. Therefore, the steel commonly used for low-temperature pressure vessels (LNG, O2, N2) is generally 304.

304H has a higher carbon content, while 304L has a lower carbon content. 304H exhibits better performance, particularly in terms of the operating temperature; it can reach up to 850 degrees.

xThank you, all the seniors :lol

Haha, thank you all; it’s very detailed, many thanks.