What Are the Differences Between the Gray Iron Casting and Ductile Iron Casting?

As a supplier of OEM castings, I will introduce it to you.

Casting made of ductile iron is called ductile iron casting. Because of its good strength and toughness, it is widely used. However, we often hear a kind of casting called "gray iron casting". Some people who are not very proficient in casting can easily confuse the two and can't tell which one is. As a supplier of iron castings, I will introduce to you the difference between gray iron casting and ductile iron casting and how to distinguish them.

Gray Iron Casting Motor Housing

The Differences Between Gray Iron Casting and Ductile Iron Casting

Ductile Iron Casting Pump Housing

The graphite in the gray iron casting organization is in the form of flakes, and the graphite in the ductile iron casting organization is in the form of spheres.

Organizational differences lead to huge differences in their performance

Gray iron casting has high brittleness and good vibration damping performance. It is mainly used to produce a variety of bases with low strength requirements and mainly bear compressive stress.

The ductile iron casting has a high strength, which is comparable to medium carbon steel. And it has a certain degree of plasticity and good toughness. It is often used to make some workpieces with high toughness requirements and complex shapes.

Ductile iron casting generally can be strengthened by heat treatment, while gray iron casting generally cannot be strengthened by heat treatment.

Compared with gray iron casting, ductile iron casting has an absolute advantage in strength. The tensile strength of ductile iron casting is 60k, while the tensile strength of gray iron casting is only 31k.

The strength ratio of ductile iron casting is much better than that of gray iron casting. The strength of ductile iron casting is comparable to that of cast steel. Ductile iron casting is the same as gray iron casting in terms of corrosion resistance.

How to Distinguish Between Gray Iron Casting and Ductile Iron Casting?

Generally speaking, there are roughly five methods to identify from the aspects of appearance and parameter detection:

1. Observe naked eye from the appearance of percussion fracture (not a machined surface). The ductile iron casting has fine grains and is black-gray. The gray iron casting parts have relatively coarse grains, appearing off-white, and the crystal faces have metallic luster.

2. From the processing surface, ductile iron casting is brighter than gray cast iron, and its structure is finer than gray iron casting.

3. Use tapping sound to judge. The ductile iron casting has a crisp sound and a long echo, and the percussion sound is similar to that of carbon steel; the gray iron casting has no echo and the sound is muffled.

4. Judging from the sparks of the grinding wheel, the streamline of the gray iron casting fire bouquet is thin and short, orange-red or dark red, with feathery tail flowers at the tail.

5. From the point of view of tensile strength δb, the δb value of ductile iron casting parts is between 400 and 900MPa, and the δ value of gray iron casting parts is between 80 and 340MPa. δb can be measured with a portable Li-style hardness tester.

HEBEI YOGEM is a supplier of OEM castings.

The materials are mainly involved in grey iron/ductile iron, aluminum alloy, stainless steel, duplex/supper duplex, alloy steel, heat-resistant steel etc.