Introduction to Hastelloy C-22 Alloy

The Hastelloy C-22 series alloys belong to the Ni-Cr-Mo family and were first developed as early as the 1940s. To address issues such as significantly reduced corrosion resistance in welds compared to the base metal, along with susceptibility to pitting and crevice corrosion in highly corrosive environments observed in Hastelloy C-276, Haynes International Inc. spent years researching and eventually developed the C-22 alloy in the 1980s. By adjusting its chemical composition, C-22 achieves a more stable crystal structure, maintaining excellent resistance to both uniform and localized corrosion even in the welded condition.

Chemical Composition of Hastelloy C-22 Alloy

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Physical Properties of Hastelloy C22:

Mechanical Properties of Hastelloy C-22 at Room Temperature:

Welding Process for Hastelloy C-22 Alloy

Hastelloy alloys exhibit excellent weldability and, with proper process measures, can fully meet relevant standard requirements.

When welding Hastelloy with austenitic stainless steels such as 304, 316L, and 904L, nickel-based alloy welding materials are the preferred choice to ensure the corrosion resistance of both the weld joint and the base metal on the nickel alloy side.

Depending on the product structure and actual welding conditions, manual TIG (Tungsten Inert Gas) welding is the primary method for welding 4mm thick C-22 alloy.

Hastelloy C-22 has a stronger tendency for cold work hardening compared to austenitic stainless steels like 304 and 316, with a cold work hardening tendency similar to that of 904L.

Welding C-22 material differs in many aspects from welding austenitic stainless steel, so welders involved in product manufacturing should receive welding skill training before formal production begins.

Research on Laser Welding of Hastelloy C-22

Electrode potential measurements indicate that the electrode potential of filler wire TIG welds in C-22 Hastelloy is very close to that of the base metal, while the electrode potential of laser welds is higher than that of both filler wire TIG welds and the base metal. This suggests that laser welds offer superior corrosion resistance compared to filler wire TIG welds and the base metal.

From the polarization curves, it can be seen that at the same external current, the electrode potentials in descending order are: as-welded laser weld > solution-treated laser weld > base metal > filler wire TIG weld. This order also reflects their corrosion resistance in practical working environments.

Chemical corrosion tests show that the corrosion rate of laser welds is lower than that of TIG welds, indicating that laser welds have higher corrosion resistance than TIG welds. This further confirms that laser welding is beneficial for improving the corrosion resistance of joints. The above provides an introduction to the material and properties of Hastelloy C-22.

We can supply various specifications of plates, bars, strips, wires, discs, ring blanks, and ring forgings. Bars are supplied in hot-rolled or hot-forged condition, with surfaces ground or turned; discs and ring blanks are supplied in forged condition; rings are supplied in solution-treated condition; plates are supplied after solution treatment, pickling, straightening, and edge trimming; strips are delivered cold-rolled, solution-treated, and descaled; wires are supplied as solution-treated and pickled in coil or straight lengths, or as solution-treated straight lengths with fine grinding.