MAT 21 is a nickel-20 chromium-20 molybdenum-2 tantalum alloy. The very high molybdenum and tantalum content gives excellent general, pitting, and crevice corrosion resistance. The alloy was developed to be resistant to sulfuric acid dew point corrosion. Applications include scrubbers for flue gas desulfurization and heat exchangers to recover waste heat at low temperatures in fossil fuel fired plants. The corrosion resistance of welded joints does not degrade in the as-welded condition. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fracture toughness. It also includes information on low and high temperature performance, and corrosion resistance. Filing Code: Ni-532. Producer or source: Mitsubishi Materials Corporation, Okegawa Plant.