01 — Materials
Ductile iron casting (EN-GJS)
Spheroidal graphite cast iron; classified by EN 1563; high strength and clear elongation at fracture.
- Awaiting quality confirmation
Materials
Cast iron falls into two groups according to the form of the graphite: spheroidal graphite gives ductile iron and flake graphite gives grey iron. This page summarises the standard grades and selection criteria of the two materials.
01 — Definition
What is cast iron?
Cast iron is a casting alloy based on iron, carbon and silicon, in which the carbon largely separates out as graphite. The shape of the graphite determines the mechanical behaviour of the material: spheroidal graphite forms ductile (spheroidal graphite) cast iron, and flake graphite forms grey (flake graphite) cast iron. In Turkey the name "pik döküm" is used for flake graphite cast iron; it does not mean pig iron (the raw iron ingot).
By graphite shape
- Sphere (nodule)
- Ductile iron casting (EN-GJS)
- Flake (lamella)
- Grey iron casting (EN-GJL)
02 — Materials
Overview of the two materials
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02 — Materials
Grey iron casting (EN-GJL)
Flake graphite cast iron; classified by EN 1561; stands out for vibration damping and thermal conductivity.
- Awaiting quality confirmation
03 — Comparison
Comparison table
| Property | Ductile iron (EN-GJS) | Grey iron (EN-GJL) |
|---|---|---|
| Graphite shape | Sphere (nodule) | Flake (lamella) |
| Standard | EN 1563 | EN 1561 |
| Older DIN designation | GGG | GG |
| Tensile strength | At least 400-700 MPa depending on the grade (grade table) | In the range 150-450 MPa depending on the grade (EN-GJL-150 to 350) |
| Elongation at fracture | Clear (at least 2-15 % depending on the grade) | Low |
| Vibration damping | Lower | Higher |
| Thermal conductivity | Lower | Higher |
| Typical deciding criterion | Load, impact, ductility requirement | Damping, thermal conductivity, cost, castability |
The table scrolls horizontally on narrow screens
- The qualitative comparisons are general material information; numerical properties vary with grade and section.
04 — Selection
What information is needed when choosing a grade?
To choose the material grade correctly, the following information is needed at the quotation stage:
- Load type (static, dynamic, impact).
- Operating temperature and environment (corrosive, humid, etc.).
- Section thickness and weight of the part.
- Machining and coating requirements.
- The standard and grade stated in the specification (EN-GJS / EN-GJL or the older GGG / GG designation).
05 — Other types
Other types of cast iron
Besides these two main types, the standards also define types such as austempered ductile iron produced by heat treatment (ADI, EN 1564), compacted graphite iron (ISO 16112), austenitic cast irons (EN 13835) and abrasion-resistant cast irons (EN 12513).
06 — Services
Related services
08 — FAQ
Frequently asked questions
What is the main difference between ductile iron and grey iron?
The difference is in the shape of the graphite: in ductile iron the graphite is spheroidal, in grey iron it is flake-shaped. For this reason ductile iron offers higher strength and elongation at fracture, while grey iron offers better vibration damping and thermal conductivity.
Is "pik döküm" pig iron?
No. In Turkey the name "pik döküm" is used for flake graphite (grey) cast iron; it does not correspond to pig iron, the raw iron ingot.
Are EN-GJS and GGG the same?
GGG is the older DIN designation; it corresponds approximately to designations such as EN-GJS-400-15. The equivalence is not exact; if a specification says GGG, its equivalent should be confirmed before ordering.
Which materials does SYC Demir Döküm produce parts from?
SYC Demir Döküm produces parts from grey and ductile cast iron. You can clarify which EN-GJL or EN-GJS grade can be produced with our team by requesting a quote with your drawing and specification.
Request a quote for your part
You can start with a drawing or a short description.