A743 CF8M

ASTM A743 CF8M is an austenitic stainless steel casting alloy known for its excellent corrosion resistance and good mechanical properties. Designated CF8M in the ASTM alloy system, it is the cast equivalent of AISI 316 stainless steel, containing chromium, nickel, and molybdenum for enhanced corrosion resistance. CF8M is classified under ASTM A743 (for general corrosion-resistant castings) and is also covered by ASTM A351 (for pressure-containing castings) – both standards specify essentially the same chemistry and properties for CF8M. The “M” in CF8M indicates the addition of molybdenum (~2–3%), which boosts resistance to pitting and crevice corrosion compared to molybdenum-free grades like CF8 (cast 304). In the alloy designation “CF8M”, C denotes a corrosion-resistant steel, F indicates roughly an 18–20% Cr, 8–12% Ni iron-based alloy, 8 signifies a maximum carbon content of 0.08%, and M stands for molybdenum addition. The alloy solidifies as a predominantly austenitic matrix with a small fraction of delta ferrite (typically 5–20%) to improve castability (reducing hot-cracking). After proper heat treatment, CF8M castings have a fully austenitic microstructure with any ferrite finely dispersed. This grade is widely used for cast valves, pumps, flanges, and other components requiring high corrosion resistance in chemical, marine, and other corrosive environments. It offers a combination of good strength, ductility, and toughness, making it suitable for service in a range of temperatures and media.