GGG-Ni22 belongs to a different family from the standard ferritic DIN ductile irons: it's an austenitic ductile (nodular graphite) iron, part of the group commonly known in industry by the trade name "Ni-Resist." Where GGG-35.3 and GGG-40 stay ferritic with only trace alloying, GGG-Ni22 carries roughly 21–24% nickel — enough to shift the iron matrix itself from ferrite/pearlite into a fully austenitic structure, the same crystal form found in austenitic stainless steels. That matrix change is what drives everything distinctive about this alloy: it's non-magnetic, it retains good toughness down to cryogenic temperatures where ferritic irons would turn brittle, and it holds up far better than standard ductile iron in corrosive environments including seawater, dilute acids, and caustic solutions.

Because GGG-Ni22 carries essentially no chromium, it leans more on its high nickel content for corrosion resistance rather than the oxide-scale protection chromium provides, which makes it a slightly better fit for reducing or neutral corrosive media than for high-temperature oxidizing service. Typical applications include pump housings and impellers, valve bodies, non-magnetic instrument housings, and components exposed to seawater or mild chemical attack where standard cast iron would corrode unacceptably fast.

GGG-Ni22 cuts noticeably differently from a standard ferritic ductile iron, and the difference comes down to its austenitic matrix. Rather than the reasonably brittle, chip-breaking behavior of ferritic or pearlitic cast iron, this material behaves much like an austenitic stainless steel: it's tough, somewhat gummy, and prone to work hardening if the tool rubs instead of cutting cleanly. Cutting forces and heat generation at the edge run meaningfully higher than on the standard DIN ductile iron grades, even though the graphite nodules still provide some internal chip-breaking benefit.

Because the matrix work-hardens readily, maintaining a constant, adequate feed rate matters more here than on brittle cast iron — dwelling, rubbing, or interrupting the cut lets the surface harden and makes the next pass considerably harder to start cleanly. A sharp cutting edge with a more positive geometry than you'd use on standard cast iron helps the tool shear the material rather than push and deform it, which keeps both tool wear and work hardening in check.

Reduced cutting speeds compared with standard ductile iron, robust and heat-resistant carbide grades, and rigid, vibration-free setups all pay off disproportionately on this alloy. Coolant helps manage the heat buildup that this tougher matrix generates at the cutting edge.