Listed manufacturers
What is a ductile iron casting?
A small addition of magnesium or a similar element to the molten iron makes the graphite form as spheres instead of flakes. The result is a material with high strength, good ductility and shock resistance, and castings can be heat-treated for different property ranges. It is widely used for pipes and fittings, pump and valve bodies, gears, crankshafts, brackets and parts that carry tension or impact.
Ductile Iron Casting or grey iron casting?
Ductile iron is stronger, tougher and can take shock loads, but it costs more and is harder to cast without defects. Grey iron is the economical choice for parts that are mostly in compression or need vibration damping.
What to specify when you ask for a quote
- Grade, with the minimum tensile strength and elongation you need.
- Matrix or heat treatment required for hardness or wear.
- Casting weight, dimensions and tolerance class.
- Nodularity and the microstructure checks you require.
- Pressure testing or non-destructive tests for pressure-containing parts.
- Pattern ownership, machining and the certificates to be supplied.
Where it is used
- Water TreatmentWater pipes, fittings and valve bodies.
- AutomotiveCrankshafts, suspension parts and housings.
- PumpsHigh-pressure pump and valve bodies.
Frequently asked questions
What is SG iron?
SG iron stands for spheroidal graphite iron, another name for ductile iron. The graphite forms spheres, which makes the metal stronger and tougher than grey iron.
When should I choose ductile iron over steel?
Ductile iron castings can replace steel castings or fabrications when the shape is complex and the loads are moderate, often at lower cost. For the highest strength and toughness, or for very high temperatures, steel may be required.
How is the quality of ductile iron checked?
By chemical analysis, tensile and hardness tests, and examination of the microstructure for nodularity. Ask the foundry for the test report for each batch.
Can ductile iron be welded or heat-treated?
It can be heat-treated to adjust strength and hardness, and it can be welded with care and the right procedure. Ask the foundry before welding a casting, because incorrect welding can cause cracks.