Hastelloy C-4 (Alloy C-4) is a nickel-chromium-molybdenum alloy with outstanding high temperature stability. It has high ductility and corrosion resistance. It is high temperature resistance up to 1900(1038) makes it suitable for most chemical process application in the as welded condition. Hastelloy C4 is a nickel-chromium-molybdenum alloy which has improved thermal stability. In this alloy, the tungsten was totally omitted and the iron content was reduced to approximately 1%. The alloy also contains approximately 0.3% Ti.

Outstanding high-temperature stability; exhibits good ductility and corrosion resistance after long-time aging at 650 to 1040 (1200-1900 ). Resists formation of grain-boundary precipitates in weld heat-affected zones, and is suitable for most chemical process applications in the as-welded condition. Has excellent resistance to stress-corrosion cracking and to oxidizing atmospheres up to 1040  (1900 ).

Hastelloy C4 has exceptional resistance to a variety of chemical process environments, including hot contaminated mineral acids, solvents, chlorine, and chlorine-contaminated media (organic and inorganic, dry chlorine, formic and acetic acids, acetic anhydride, seawater, and brine). The general corrosion resistance of Alloy C276 and Alloy C4 was essentially the same in many corrosive environments, except that in strongly reducing media like hydrochloric acid, Alloy C276 was better; but in highly oxidizing media, the opposite was true, that is, Alloy C4 was better. Alloy C4 offers good corrosion resistance to a wide variety of media including organic acids and acid chloride solutions.