What is the composition of Hastelloy C4?
Alloy C4, 2.4610, Hastelloy C-4 – Description
Alloy C4 is a tungsten-free, low-carbon, low-silicon ternary alloy of nickel, chromium, molybdenum with titanium added to stabilize residual carbon. It has excellent high temperature stability, excellent corrosion resistance and good weldability. It can be considered as a more stable and better weldable variant of Alloy C-276.
Thermal Stability and Weldability - Alloy C4 exhibits good ductility and corrosion resistance after long-term aging at 650 to 1040°C. It is able to suppress the formation of grain boundary precipitates in the weld heat affected zone and is suitable for most chemical process applications without any additional post weld heat treatment. It has excellent resistance to stress corrosion cracking and resistance to oxidizing atmospheres up to 1040°C.
Applications
Alloy C-4 is mainly used in chemical processing.
Heat Treatment, Processing and Machining
Recommended Processing and Heat Treatment Parameters:
Forging: 1177-954°C
Soft Annealing: 1065±14°C; 30 minutes; WQ
Forging - The alloy can be hot forged within a narrow temperature range, starting at 1177°C and finishing at 954°C. Moderate reduction and frequent reheating are recommended for best results. The alloy is strain sensitive.
Cold working does not reduce its general corrosion resistance, but it will affect its resistance to stress corrosion cracking. Annealing after processing is essential to obtain the best corrosion performance.
Annealing consists of heating to 1066°C and water quenching. A hold at the annealing temperature of 10 to 30 minutes is recommended, with thicker structures requiring 30 minutes. Annealing is essential after hot forming operations and any cold forming that results in an outer fiber elongation of 7% or more.
Post weld heat treatment for basic service - Heat the material to 705 °C and hold at that temperature for at least 0.5 hour per 25 mm thickness. Determine the heating and cooling rates based on the part shape. For complex shapes with non-uniform thickness, the heating and cooling rates should be 111 °C per hour. Shapes with uniform thickness may use faster heating and air cooling rates.
