Alloy 304/304H has good resistance to atmospheric corrosion, foods and beverages and to many organic and inorganic chemicals in moderately oxidizing to moderately reducing environments. The high chromium content of the alloy provides resistance to oxidizing solutions such as nitric acid up to 55% weight and up to 176°F (80°C).
Alloy 304/304H also resists moderately aggressive organic acids such as acetic. The nickel present in the alloy provides resistance to moderately reducing solutions such as pure phosphoric acid, whatever the concentration, in cold solutions and up to 10% diluted hot solutions. The alloy can also operate successfully in caustic solutions free of chlorides or fluorides at moderate temperatures.
Alloy 304/304H does not perform well in more highly reducing environments such as those containing chlorides and sulfuric acid.
Alloy 304/304H performs well in fresh water service with low levels of chlorides (less than 100ppm). At higher chloride levels the grade is susceptible to crevice corrosion and pitting. For successful performance under these more severe conditions, higher molybdenum content is need such as 316/316L. Alloy 304/304H is not recommended for service in marine environments.
In most instances, the corrosion resistance of Alloys 304, 304L and 30H will be roughly equal in most corrosive environments. However, in environments that are sufficiently corrosive to cause intergranular corrosion of welds and heat-affected zones Alloy 304L should be used because of its low carbon content.
Weight % (all values are maximum unless a range is otherwise indicated)
|Chromium||18.0 min.-20.0 max.||18.0 min.-20.0 max.|
|Nickel||8.0 min.-10.5 max.||8.0 min.-10.5 max.|
|Carbon||0.08||0.04 min-0.10 max.|
|Typical*||Type 304||Type 304H|
|0.2% Offset Yield Strength, ksi||43||30 min.||30 min.|
|Ultimate Tensile Strength, ksi||91||75 min.||70 min.|
|Elongation in 2 inches, %||58||40 min.||140 min.|
|Reduction in Area, %||68||—||—|
|Hardness, Rockwell B||83||92 max.||92 max.|