CI · cast iron
Ductile Iron GGG50 (EN-GJS-500-7)
A higher-strength ductile iron with less elongation: harder matrix, longer tool life needed, and the cutting speeds step down accordingly.
Quoting this material
- Typical lead time
- 15–25 working days
- Condition
- As cast or normalised
- 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 higher-strength ductile iron with less elongation: harder matrix, longer tool life needed, and the cutting speeds step down accordingly.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 500 | MPa |
| Yield strength (0.2%) | 320 | MPa |
| Elongation | 7 | % |
| Hardness | 170–230 | HB |
| Fatigue strength | Good for a casting | - |
| Modulus of elasticity | 169 | GPa |
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 or normalised
Heat treatment
Achieved by matrix control in the foundry - a more pearlitic structure than the 400 grade. It can be austempered to ADI, which is a different and much stronger material altogether.
Achievable surface finish
Ra 1.6 µm
Ra 0.8 µm
Takes a good finish and holds it in service better than the lower grade, which matters on a sliding or sealing surface.
Tooling and cutting parameters
Cutting speed
- 120–250 m/min (carbide)
Feed
- 0.15–0.30 mm/rev turning · 0.08–0.20 mm/tooth milling
Tooling
- Coated carbide with a tough substrate
Coolant
- Flood or mist
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
- Gears and gearbox housings
- Crankshafts and camshafts
- Heavy vehicle brake and hub parts
- Pressure pipework fittings
- Agricultural machinery components
DFM notes for this grade
- It is the middle grade: more strength than the 400 with enough ductility to survive a casting defect or a shock, and it machines reasonably
- Where the part is a gear or a crankshaft, ADI or a forging is often the better answer - GGG50 is the cast-iron solution, not always the best solution
- Section thickness affects the matrix: a heavy section cools slowly and comes out softer than a thin one, so a single casting can have two hardnesses in it
Questions buyers ask
- Why does section thickness matter on a ductile iron casting?
- Because cooling rate controls the matrix. A thick section cools slowly and ends up with more ferrite and a softer surface; a thin section cools fast and is more pearlitic and harder. On a casting with both, hardness varies - which matters if you are assuming a single cutting speed.
- Is GGG50 a gear material?
- It is used for gears in slow, heavily loaded applications where noise and cost matter more than efficiency: agricultural and industrial drives. For higher speed or higher load, a hardened steel gear or ADI is the better answer.
Grades we would quote instead
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.
GGG60 / Ductile Iron 600-3
5/10A high-strength ductile iron: 600 MPa with 3% elongation.
ADI (Austempered Ductile Iron)
3/10Ductile iron put through an austempering heat treatment to reach 800–1,100 MPa.