ASTM StandardsBarButt Weld FittingsForgingsPipe, Welded & SeamlessTube, WeldedTube, SeamlessPlateA 276, A479A403A182A312A249A213A240
Minimum Physical PropertiesTensile StrengthYield StrengthElongationHardness75 KSI / 515 MPA30 KSI / 205 MPA40% Min.RB 92 Max.
Chemical Composition (wt%)CMnPSSiNiCrFe0.04 – 0.102.00 Max0.045 Max0.03 Max1.00 Max8.0 – 11.018.0 – 20.0Balance
Properties
304L is probably the world’s most common stainless steel. The “L” stands for “Low” and refers to the carbon content. 0.035 percent is the maximum allowable carbon content in 304L grade. The “H” in 304H stands for “High” carbon content. 304H must contain not less than 0.04 percent carbon, nor more than 0.10 percent.
The higher carbon content of 304H increases its strength, so the ASTM tensile and yield strength of 304H is greater than 304L.
304H has greater short term and long term creep strength than 304L at temperatures up to 500 degrees C, and 304H is more resistant to sensitization than 304L.
In ASME pressure vessels for use above 525 degrees C, the carbon content of 304 stainless must be 4 percent or more. 304H is required in such applications.
Applications
304H is most commonly used in petroleum refineries. It is also found in boilers. Other applications include heat exchangers, condensers, pipelines, cooling towers, steam exhausts, and electric generation plants. On occasion it will also be found in fertilizer and chemical plants.
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