There is tungsten added in the grade to resist pitting corrosion and the molybdenum content resists other localized corrosion attacks. A very small quantity of vanadium is added to impart the required hardness. Other alloying elements make sure the grade is machinable and retains its mechanical properties at sufficient temperatures.
It is a solid-phase solution alloy, which naturally makes it durable. Being a nickel compound, the alloy generally resists various chemicals, promotes toughness and provides general corrosion resistance. Hastelloy C276 is one of the rare alloys that resists wet chloride gas, chlorine dioxide and, hypochlorite solutions. It gives great resistance to chloride stress corrosion cracking and other chloride solutions. When tested for cracking under 45% boiling magnesium chloride, the grade 316L took 2 hours to crack, the grade 254SMO took 24 hours to crack, whilst the Hastelloy C276 took 1000 hours to crack. The microstructure of the alloy gives it great welding, forming and machinability. The low carbon content makes the alloy resistant to inter-granular corrosion at the heat affected zones. The grade got into applications to ease the concerns over welding. The low carbon content restricts formation of carbides at the grain boundaries.
The alloy also has considerable impact strength -- a 10mm thickness plate could withstand 470J at room temperature under Charpy v-notch test. Hence, its uses in dynamic applications. The alloy can be conveniently extruded, hot worked and cold worked. The alloy might tend to work harden. At elevated temperatures - strain age cracking problem, common with other strengthened alloys is avoided in this alloy. Hot working can be suitably done around 880-1240°C while heavier sections can be heated to a minimum of 1100°C before forming. The alloy shows its versatility in various conditions and can be conveniently processed and used in many applications.
