The specific meaning of H in 304H
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May I ask, in 304H, does the ‘H’ refer to high carbon content or heat resistance?
It refers to the 304 series designation, which indicates the level of carbon content; 304H has a higher carbon content. Specifically, 304 has a carbon content of 0.08%, 304L has 0.030%, while 304H has a carbon content of 0.04–0.10%. :lol
There seems to be some issue upstairs; I remember that for 304, it’s 0.06–7%, for 304L it’s 0.030%, and for 304H it’s >0.04%.
It’s probably because different standards are used. But from an English perspective, “h” means high. Many standards have to be memorized through English.
The guy on the 2nd floor is right. Carbon content: Reduce or increase the carbon content. 304L is an ultra-low carbon version of 304 steel. Reducing the carbon content can improve corrosion resistance, particularly the intergranular corrosion susceptibility of 304 steel after welding; under conditions that meet the requirements for mechanical strength, it can be used to manufacture welded components with large cross-sectional dimensions. 304H increases the carbon content to 0.10%, enhancing the strength of 304 steel and making the austenite more stable; it is therefore more suitable for use in low-temperature environments and in components that require non-magnetic properties.
It seems this grade is not available in the domestic market; it mainly refers to those with a high carbon content
304H should refer to 304 heat-resistant steel, with a carbon content of 0.04–0.1； Ni: 8-11 ； The other nominal contents are the same as those of 304. 304H exhibits good formability and weldability, corrosion resistance, high permanent strength and structural stability, as well as excellent cold formability. The maximum operating temperature can reach 650°C, while the maximum oxidation resistance temperature can reach 850°C. Applications: Used to manufacture superheater tubes, reheater tubes, steam pipes for large-scale generator sets, as well as heat exchange tubes in the petrochemical industry. The allowable oxidation resistance temperature for boiler tubes is 705°C. However, L was right – it refers to low-carbon 304 stainless steel, with a carbon content of 0.03% and Ni content of 9–13%. Its strength is slightly lower than that of 304, but its corrosion resistance is better; it is more resistant to corrosion than 304.
I only knew about 304L; I had never heard of 304H. Thank you, OP – it’s great to learn something new!