Gray & Ductile Iron

Gray & Ductile Iron

While gray iron does not have a measurable yield strength, the range for tensile strength is 20,000 psi – 60,000 psi. Impact – Ductile iron has a greater resistance to impacts, and is able to resist a minimum of 7 foot pounds of impact (versus 2 pounds of impact for gray.

The silicon promotes good corrosion resistance and increased fluidity when casting. Gray iron is generally considered easy to weld. Compared to the more modern iron alloys, gray iron has a low tensile strength and ductility; therefore, its impact and shock resistance is almost non-existent. The popularity of grey cast iron components (gray iron castings) is because grey iron is one of the cheapest types of iron castings to produce. It has acceptable ductility, tensile strength, yield strength, and impact resistance for most applications. White cast iron is harder than grey, to the point that it is quite brittle. Grey iron, by contrast, is softer but stronger. The two types are sometimes combined, allowing a piece to be made with a hard outer coating of white iron and a strong core of grey. Gray cast iron has a high dampening capacity and is corrosion resistant. However it is brittle, and can be difficult to machine as it is hard to produce a smooth surface and can reduce tool life. Malleable iron has good shock resistance, is ductile and is very machinable.