Duraloy 22H is a proprietary cast, high-carbon nickel-chromium-tungsten heat-resisting alloy produced by Duraloy Technologies (originally developed under the Blaw-Knox name). It corresponds to the general alloy family covered by DIN 2.4879 (G-NiCr28W / G-X45NiCrWSi4828), a 28% chromium - 50% nickel - 5% tungsten cast matrix designed for continuous service at 950-1250 degC (1740-2280 degF).

The high nickel content gives strong resistance to carburization, while the high chromium level provides useful resistance to sulphidation under oxidizing conditions. Typical applications are highly stressed furnace parts, sintering and calcining muffles, cement kiln components exposed to hot abrasion, radiant tubes, and pyrolysis coils - all centrifugally or statically cast components rather than wrought bar or plate stock.

As a cast alloy, Duraloy 22H solidifies with a high-alloy austenitic matrix containing a significant network of primary and secondary chromium carbides, a direct result of its unusually high (roughly 0.5%) carbon content relative to wrought superalloys. This carbide network is what gives the material its hot strength and wear resistance, but it also makes the as-cast material considerably more abrasive to cut than a comparable wrought nickel alloy.

Duraloy 22H should be approached as a cast heat-resisting alloy first and a nickel alloy second. Centrifugal and static castings in this family typically carry a hard, oxide-rich outer skin from the casting process, and the bulk material contains a dense network of chromium carbides formed by its high carbon content. That carbide network is highly abrasive to cutting edges, causing rapid flank wear independent of the thermal effects common to wrought nickel alloys.

Beneath the abrasive-wear concern, the same fundamental nickel-superalloy issues still apply: low thermal conductivity concentrates heat at the cutting edge instead of carrying it off in the chip, and the austenitic matrix work-hardens under light or interrupted cuts. Because castings often present irregular, interrupted surfaces (parting lines, riser remnants, variable wall sections), tool edges see repeated impact loading in addition to steady-state wear, favoring tougher carbide substrates over the most wear-optimized but brittle grades.

Recommended practice is to machine below the as-cast skin wherever possible (or remove it in a dedicated roughing pass with a sacrificial edge), use rigid, vibration-damped setups, favor tougher coated-carbide grades able to withstand interrupted engagement, keep speeds on the low end of the nickel-alloy range to manage both carbide abrasion and heat, and maintain feed rates sufficient to get beneath any work-hardened layer rather than dwelling in it.