GRADE GUIDE · HASTELLOY C-276
Hastelloy C-276 (UNS N10276) is the benchmark corrosion alloy for severe chemical service: a nickel-molybdenum-chromium-tungsten chemistry that survives wet chlorine, hot mixed acids and oxidising-plus-reducing conditions that destroy everything else. When a process stream is genuinely nasty, C-276 is the default answer.
Also listed as: UNS N10276 · EN 2.4819 · NiMo16Cr15W · Alloy C-276
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C-276's trick is covering both corrosion regimes at once — 16% molybdenum handles reducing acids while 16% chromium handles oxidising ones, so upset conditions and contaminated streams don't catch it out. Its ultra-low carbon (≤ 0.01%) means welds keep their corrosion resistance without post-weld heat treatment, which made it the fabrication-friendly successor to the original alloy C.
Regionally it shows up in chemical plants, flue-gas scrubbers, effluent systems and the sour, chloride-laden corners of gas processing. It is also among the most expensive metals on this platform per kilogram — which is precisely why certified surplus matters: a patch plate or dip-tube's worth of C-276 off-cut costs a fraction of a mill order. Certificates ride every badged listing.
In hot reducing acids, wet chlorine and mixed-acid chemistry, where C-276's extra molybdenum keeps it passive. For seawater-plus-heat or sour-gas mechanical duty, 625 usually covers it at lower cost.
For most corrosion service, no — the ultra-low carbon and stabilised chemistry keep the heat-affected zone resistant as-welded. That is the alloy's core fabrication advantage.
As surplus, whenever possible. Mill minimums for exotic alloys are brutal for repair-scale needs; a certified off-cut with an MTC badge gives the same pedigree at a fraction of the outlay.