Both steel and cast iron are popular metals, but they are often used very differently. The key factor distinguishing one from the other is how much carbon each contains, and to a lesser extent, how much silicon. While this may seem like a subtle distinction, it has major implications for the properties and uses of cast iron and steel.
Cast Iron: Benefits and Uses
Like steel, cast iron is an iron-based alloy. However, to be considered cast iron, the metal must have a 2-4% carbon content and 1-3% silicon content by weight. This chemistry imparts cast iron with a number of useful properties:
Cast iron can actually be further subdivided into grey iron, white iron, ductile iron, and malleable iron. Each type focuses on improving certain properties for a specific application, like higher hardness in white cast iron.
The uses for cast iron are wide-reaching, but here are a few notable applications:
Cast iron frying pans and other cookware
Automotive engine blocks, brake disks, and numerous other parts
Residential fence gates, decorative light posts, fireplace elements, and other furnishings
Valves, fittings, and manhole covers in water and sewer applications
Chains, gears, shafts, linkages, and moreSteel: Benefits and Uses
Steel: Benefits and Uses
Similar to cast iron, steels are iron-based alloys with a few distinct categories. All steels have some carbon content up to a limit of 2% by weight and can be divided into either carbon steel or alloy steel.
They can be further subdivided into low-carbon steels, stainless steels, tool steels, microalloyed steels, and more. While these can offer numerous additional benefits, like high strength and corrosion resistance from stainless steels, this article will focus on cast steel alloys like those defined by ASTM A148.
Since cast steel is more expensive than cast iron, its main advantages over cast iron are:
Tensile Strength – Depending on the alloy used, cast steel can potentially have a much higher tensile strength than cast iron.
Toughness/Ductility – Under high stress, steel can deform (temporarily or permanently) without breaking. While this might mean less stiffness in certain applications, it reduces the likelihood of cracking and means better impact performance.
Weldability – Depending on the alloy used, steel offers good weldability, whereas cast iron is challenging to weld without causing cracking.
While forging, rolling, and casting are all possible for steel products, some key applications focused on cast steel are:
Rail car wheels, frames, and bolsters
Mining machinery, construction equipment, and heavy trucks
Heavy duty pumps, valves, and fittings
Turbochargers, engine blocks, and other automotive parts
Turbines and other components in power station assemblies
Machined cast iron and steel products :
Cast iron is certainly easier and cheaper to machine than cast steel, but machinability varies greatly between alloys. So if you are designing a product that requires long machining operations, it may be worthwhile to review the available alloys to find one with better machinability.
But even if you are limited to more difficult materials, an experienced, world-class machine shop can reduce machining time to save on machining costs. Let us provide fast, reliable machining services for your company’s various materials and product types.
Post time: Feb-06-2023
