CI · cast iron
Austenitic Cast Iron Ni-Resist D2 (EN-GJSA-XNiCr20-2)
A nickel-alloyed austenitic iron: it machines more slowly than grey iron, with the gummy chip and work-hardening of an austenitic steel, and it is bought for corrosion and heat resistance.
Quoting this material
- Typical lead time
- 20–30 working days
- Condition
- As cast
- Achievable finish
- Ra 1.6 µm typical · Ra 0.8 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
A nickel-alloyed austenitic iron: it machines more slowly than grey iron, with the gummy chip and work-hardening of an austenitic steel, and it is bought for corrosion and heat resistance.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 370–400 | MPa |
| Yield strength (0.2%) | 210–240 | MPa |
| Elongation | 7–15 | % |
| Hardness | 140–190 | HB |
| Magnetic permeability | Essentially non-magnetic | - |
| Thermal conductivity | 12 | W/m·K |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
As cast
Heat treatment
No hardening treatment. The austenitic matrix is achieved by the nickel content in the melt - roughly 20% nickel is what makes the material austenitic, non-magnetic and corrosion resistant.
Achievable surface finish
Ra 1.6 µm
Ra 0.8 µm
Cuts to a dull, clean finish; the austenitic matrix smears rather than shearing, so a sharp tool is essential.
Tooling and cutting parameters
Cutting speed
- 80–150 m/min (carbide)
Feed
- 0.10–0.25 mm/rev turning · 0.08–0.18 mm/tooth milling
Tooling
- Coated carbide, sharp positive rake; expect the tool life of a stainless rather than a cast iron
Coolant
- Flood
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Seawater pump bodies and impellers
- Exhaust manifolds and turbo housings
- Chemical process equipment
- Non-magnetic components
- Heat treatment fixtures
DFM notes for this grade
- It is bought for three specific properties: corrosion resistance in seawater, oxidation resistance at temperature, and a non-magnetic structure. If the design needs none of those, grey or ductile iron is cheaper and machines better
- Only a small proportion of Ni-Resist parts are machined from solid - most are castings, so the machining is a finishing operation on a near-net shape
- Not a bearing material. It resists corrosion well and has poor wear behaviour, so it is used where sliding contact is not the duty
Questions buyers ask
- Why is Ni-Resist used for seawater pumps?
- It resists seawater corrosion and it is available as a casting, so a pump casing or impeller can be produced economically in a corrosion-resistant material. Against a bronze or a stainless it is often the cheaper way to get a complex corrosion-resistant shape.
- Why is it non-magnetic?
- The nickel content holds the matrix in the austenitic phase, which is not ferromagnetic. That matters for components near electrical equipment or magnetometers, and it is a property grey and ductile iron do not have.
Grades we would quote instead
GJL300 (Grey Iron 300)
6/10The strongest of the standard grey irons: harder matrix, slightly tougher on the tool and still cutting clean and dry like its family.
GGG40 / Ductile Iron 400-15
6/10Ductile iron with the graphite in nodules rather than flakes: it has real elongation, it takes impact, and it machines like a soft steel with better chip control than grey iron.
316L
3/10Harder to machine than 304 and it galls more, but it is the grade for chlorides, medical and marine.