Stainless steel and iron are the two kinds of different metal alloys commonly used in casting process. Before deciding a suitable material for your item, it is necessary to understand the differences between stainless steel casting and iron casting.
What is Stainless Steel Casting?
Stainless steel casting refers to the casting technique of stainless steel alloys. Due to the good corrosion resistance and heat resistance, stainless steel castings are usually classified as either corrosion-resistant castings or heat-resistant.
Usually used casting method of stainless steel alloys is investment casting or lost wax casting process. Firstly, an aluminum mold is designed and manufactured according to 3d file of the part, then the wax pattern is produced and dipped together to form a tree assembly. Meanwhile, the assembly is dipped into the seriflux and sprayed with a fine layer of sand. After several sand spraying, the surface of the wax assembly forms a sand shell. After baking into the oven, the wax is melted and a complete shell is formed, in this way, molten stainless steel is poured into the shell, after solidification, cut the shell to have the solid cast stainless steel part.
What is Iron Casting?
Iron casting refers to the casting technique of iron alloys, including ductile iron or grey iron. Due to its low material cost and good castability of grey iron and ductile iron, iron casting is a popular forming process of complex iron parts.
Common used process of iron casting is sand casting. A pattern, usually made of wood or aluminium, is required to create the sand mould. The sand is packed around the pattern, which is a replica of the external shape of the casting. When the pattern is removed, the cavity that will form the casting remains. Molten iron liquid is poured into the sand mould where it fills the cavity. As the molten iron cools inside the mould, it forms a solid iron casting. Once cooled and solid, the casting is knocked out of the sand mould. Iron casting is most often used for making complex shapes that would be otherwise difficult or uneconomical to make by other methods.
Comparison Between Stainless Steel Casting and Iron Casting
Castability means the casting ease of metal. You can only see the liquid stainless steel or iron when they are melted under high temperature.
Stainless steel casting requires a higher melting point at around 2600˚F, while iron casting only needs about 2300˚F. That is to say, it is more difficult to melt stainless steel alloys, which take much more heat to melt. In order to casting, both stainless steel and iron could only be poured into molds at a much higher temperature than their melting points.
By comparison, cast iron does not shrink as much as steel, when filling the mold, less amount of liquid is required. Besides stainless steel has to be melted at a much higher temperature than cast iron, so the castablity of stainless steel is not as good as cast iron.
Corrosion resistance means the ability to resist corrosion. Due to the iron element, When the metal is exposed in the air, both stainless steel and cast iron oxidize when exposed to the environment, which will result in rust.
Stainless steels, as the name implies, are generally the more corrosion resistant compared to cast iron. Due to the added chromium, stainless steel is more corrosion resistant than cast iron. When the chromium attaches to the oxygen, the surface of stainless steel forms a chromium oxide layer which protects the material from corrosion. Cast iron does not typically have enough chromium to form this chromium oxide layer, allowing oxygen to bond with the iron which results in iron oxide, or rust. So if corrosion resistance is a key factor when considering the material for casting, stainless steel casting is the right way to go.
Although there are lots of advantages of cast iron, and it is widely used to produce castings. When talking about the strength and ductility, stainless steel can be considered as the leader, because it can withstand sudden impact without deforming, bending, or breaking. It is also able to withstand high stress and strain forces without fracture.
While, cast iron deforms without failure with high impact due to its ductile character. So, it has a limited range of applications while stainless steel has wide applicability in the world.
Machinability of stainless steel or cast iron means the ease with which the metal can be machined to remove the excess material at a low cost. As mentioned above, cast iron have lower melting point and less shrinkage, so it is much easier to machine than stainless steel, also the machining cost is ratively lower.
CFS Foundry has the capability of stainless steel casting in lost wax investment casting method. Any interest in stainless steel casting in China, pls feel free to contact our foundry!