Dual certified 304/304H is used as a material of construction up to 1500°F. Slight scaling begins at about 1200°F. 304/304H meets a 0.04% minimum carbon content and has a grain size of ASTM 7 or coarser. It has general corrosion resistance similar to the low carbon 304/304L. However, it is subject to carbide precipitation in the heat affected zone (HAZ) of welds. Weldments may be sensitive to HAZ intergranular corrosion in oxidizing acid environments, and to polythionic acid stress corrosion cracking. The carbide precipitation is not harmful to high temperature mechanical properties.

304/304H is welded using the 22Cr 11Ni filler wire (ER308), or covered electrodes (E308). Post-weld heat treatment is not necessary for most high-temperature service.