Difference Between Grey Cast Iron and White Cast Iron

Key Difference –Grey Cast Iron vs White Cast Iron

The differences between grey cast iron and white cast iron emerge from the composition and the color of the surface of the material after fracturing. Both of these iron casting alloys mainly contain carbon and silicon, but in different proportions. Akey differencebetween grey cast iron and white cast iron is thatafter fracturing, white cast iron gives a white coloured crack surface and grey cast iron produces a grey coloured fractured surface. This is basically due to their constituents in the alloy.

What is Grey Cast Iron?

The most commonly used category of castingalloyis grey cast iron. The composition includes about2.5% to 4% carbonand1% to 3% silicon. In the process of making grey cast iron, the proper control of carbon and硅content and maintaining the proper cooling rate prevents the formation of iron carbide during solidification.This helps to precipitategraphitedirectly from the melt as regular, commonly elongated and curved flakes in an iron matrix saturated with carbon. When it fractures, the crack path runs through flakes and the fractured surface appears in grey due to graphite present in the material.

What is White Cast Iron?

White cast iron got its name from the white,crystallinecrack surface that it imparts after fracturing. In general, most white cast iron materials containless than 4.3% of carbonandless amount of silicon. This inhibits the precipitation of carbon in the form of graphite. White cast iron is most frequently used in applications, where abrasion resistance is essential andductilityis not very significantly required. Examples are liners for cement mixers, in some drawing dies, ball mills and extrusion nozzles. White cast iron cannot beweldedbecause it is very difficult to accommodate welding-induced stress in the absence of any ductile properties in the base metal. Moreover, the heat affected zone adjacent to the weld may crack during cooling after welding.

What is the difference between Grey Cast Iron and White Cast Iron?

Composition:

Grey Cast Iron:Mostly, the composition of grey cast iron is; about 2.5% to 4.0% of carbon, 1% to 3% of silicon and the remainder balance using iron.

白铸铁：通常，白色铸铁主要含有碳和硅；约占碳的1.7％至4.5％，硅的0.5％至3％。此外，它可能包含痕量的硫，锰和磷。

Properties:

Grey Cast Iron:Grey cast iron has a higher compressive strength and high resistance to deformation. Its melting point is relatively low, 1140 ºC to 1200 ºC. It also has a greater resistance to oxidation; therefore, it rusts very slowly and this gives a permanent solution to the problem of corrosion.

白铸铁：In white cast iron carbon is present in the form of carbide of iron. It is hard and brittle, has a greater tensile strength and extremelymalleable（能够永久性地锤或压制而不会破裂或破裂）。它还具有高抗压强度和出色的耐磨性。它可以在有限的时期内保持硬度，即使是红热。它不能像其他铁体一样容易施放，因为它具有相对较高的固化温度。

Uses:

Grey Cast Iron:灰铸铁最常用的区域是：在内燃机缸，泵外壳，电箱，阀体和装饰性铸件中。它也用于烹饪设备和制动转子中。

白铸铁：White cast iron is most extensively used in crushing, grinding, milling and handling of abrasive materials.

Image Courtesy:

1. “Cast-Iron-Pan” by Evan-Amos – Own work. [Public Domain] via Commons

2.Fabulous cast-iron railings at Worships Hill in Riverhead (ii) – geograph.org.uk – 1593921By Tristan Forward [CC BY-SA 2.0], via Wikimedia Commons