Gray iron

Gray iron casting contains graphite in the form of elongated flakes of varying size and shapes. Gray iron casting requires adding more carbon to the molten iron than is necessary for the production of steel. Most forms of steel contain less than 1.2% of carbon whereas gray iron usually contains from 2.5% to 4%. Adding carbon to the iron decreases the fusion point of the metal and makes it more fluid. This makes it easier to get the metal to conform to intricate shapes.

The properties of gray iron are :
- Low shrinkage
- Easy to cast into intricate shapes
- Resistance to scoring and galling
- Excellent machining qualities
- Resistant to fatigue


Gray iron microstructure

Grades of gray iron available from Fonderie Laroche
According to ASTM-A-48 Standards
Type Tensile strength (PSI) Hardness (Brinell) Equivalent DIN 1691 Equivalent DIN EN 1561 Equivalent ISO 185
CL 25 25 000 170-229 GG15 EN-GJL-150 -
CL 30 30 000 187-241 GG15 EN-GJL-200 200
CL 35 35 000 207-225 GG20 EN-GJL-250 250
CL 40 40 000 217-269 - - -
*A-319
(For high temperatures)
PSI > 30 000
PSI < 40 000
187-255 - - -

*This type of alloy, high in chrome content can resist to temperatures as high as 1400°F (760°C). Depending on the class and type, tensile strength will oscillate between 30,000 and 40,000 PSI.

Other special alloys are also available on demand. Please call for more information.