Gray vs Ductile Iron Selector
Not sure whether to specify gray or ductile iron? Pick your top priority and get a recommendation with a typical grade.
How it decides
Ductile iron wins on tensile strength, impact toughness, ductility and fatigue. Gray iron wins on vibration damping, thermal conductivity, machinability, compressive wear and cost.
Gray vs ductile at a glance
| Property | Gray | Ductile |
|---|---|---|
| Tensile strength | Low–med | High |
| Ductility | ~0% | up to 18% |
| Damping | Excellent | Good |
| Machinability | Excellent | Good |
| Cost | Lower | Higher |
Frequently Asked Questions
What is the difference between gray and ductile iron?
Gray iron has flake graphite (brittle, great damping/machinability); ductile iron has nodular graphite, giving much higher strength and ductility.
When should I use ductile iron?
When you need tensile strength, impact resistance, fatigue life or some ductility — e.g. pressure parts and safety components.
When is gray iron the better choice?
For vibration damping, heat transfer, easy machining and lowest cost — e.g. machine bases, brake discs and housings.
Which is cheaper?
Gray iron is generally cheaper to produce than ductile iron.
Embed This Calculator (Free)
Add this free Gray vs Ductile Iron Selector to your own site or blog — copy the snippet below. Attribution links back to Matson Iron Casting.