HASTELLOY C-4 alloy is a nickel-chromium-molybdenum alloy with outstanding
high-temperature stability as evidenced by high ductility and corrosion resistance even
after aging in the 1200 to 1900°F (649 to 1038°C) range. This alloy resists the formation
of grain-boundary precipitates in the weld heat-affected zone, thus making it suitable
for most chemical process applications in the as-welded condition. C-4 alloy also
has excellent resistance to stress-corrosion cracking and to oxidizing atmospheres up to
1900°F (1038°C).

HASTELLOY C-4 alloy has exceptional resistance to wide variety of chemical process
environments. These include hot contaminated mineral acids, solvents, chlorine
and chlorine contaminated media (organic and inorganic), dry chlorine, formic and
acetic acids, acetic anhydride, and seawater and brine solutions.
HASTELLOY C-4 alloy can be forged, hot-upset, and impact extruded. Although the
alloy tends to work-harden, it can be successfully deep-drawn, spun, press formed or
punched. All of the common methods of welding can be used to weld HASTELLOY C-4
alloy, although the oxy-acetylene and submerged arc processes are not recommended
when the fabricated item is intended for use in corrosion service. Special precautions
should be taken to avoid excessive heat input.