Cast iron alloys

Alloys in cast iron

At ULDALL, we produce cast iron items in various alloys according to the customers' needs. It is important to choose the right alloy for your project, as the different properties of the alloys have a great impact on the function of the cast iron components.

Below is an excerpt of the most commonly used alloys, out of the 55 different iron alloys that we offer. 

Grey iron according to EN1561

Earlier and often still called GG.

Characteristics:
Is the classic cast iron, which has been made for more than 1,000 years. The graphite (carbon) is located in slats/flakes, which therefore distinguishes the iron from steel and SG Iron. With a sound test, you can distinguish GG from SG, as GG sounds blunt and SG sings like steel or a church bell.

Properties:
Grey iron is easy to work with and, due to the lamellar graphite, is both vibration and noise dampening. In addition, there are good lubrication, glide, pressure, and tightness properties.

Used for:
Machine racks, motors, valves, cylinders, flanges, pump housings, bearing housings, hydraulic housings, frying pans and pots.

The most commonly used alloys are:

SG iron according to EN1563

Called Nodular iron and occasionally also Meehanite® iron.

Characteristics:
This type was standardized in 1948 and takes the best properties from steel (strength) and cast iron (machinability and lubricating/sliding properties). The manufacturing process is best controlled in electric ovens, such as the ones we use at ULDALL. Magnesium is poured over with ordinary gray iron and due to the magnesium's low boiling point, the magnesium boils up through the gray iron and converts the graphite flakes into balls (nodules).

Properties:
Is still easy to work with and with good lubricating and sliding properties. But in addition, it has high tensile strength and toughness. SG can be cured partially or on the entire component with hardnesses up to 600HB. In addition, SG can be ADI-hardened under very special requirements, where the hardening increases tensile strength, impact toughness and yield strength without compromising the elongation.

Used for:
Cranks, connecting rods, valve bodies, couplings, gears or as a replacement for welded structures.

The most commonly used alloys are:

Special alloys

ULDALL has small flexible furnaces and can therefore make quick changeovers and small series, which makes casting special alloys a daily routine. We have the usual special alloys such as heat-resistant cast iron, Ni-hard and Ni-resist, but also offer specially adapted alloys that match the customer's requirements exactly. However, only alloys that have cast iron as a base - i.e. not steel or metal alloys.

Ni-Hard according to EN12513

Also called white cast iron.

Properties: 
Difficult to work with due to high content of chromium and thus an HB 400-600, but with good wear properties and acid resistance.

Used for: 
Pump housings, wear plates, coal mills, crushers and cement mixers.

Ni-resist according to EN13835

Both as Grey Iron and SG Iron.

Properties: 
Corrosion, heat and oxidation resistant. Since the main constituent in addition to Iron (Fe) is Nickel (Ni), this alloy is expensive.

Used for: 
Machine parts and steam engines that must not deform or corrode during use or are exposed to acid or salt water.

Heat-resistant cast iron

Molybdenum-based SG iron.

Properties: 
Retains much of the strength at high temperatures without deforming or building up stress.

Used for: 
Incineration grates and plants.