Ferrous alloys are iron based alloys that has extensive use in wide range of industries because of its flexibility to meet strength, toughness, and impact of diverse industrial applications. This flexibility depends on the heat treatment procedures, which modifies the final micro-structure. Examples of ferrous alloys include carbon steels, alloy steels, stainless steels, tool steels, cast iron, cast steel, maraging steel, and specialty or proprietary iron-based alloys.
Now-a-days, many alloy manufacturers are trying to meet the compositional standards of the Unified Numbering System (UNS). Unified Numbering System (UNS), jointly developed by American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE), provides an overall designation system for thousands of metals and alloys in commercial use.
Before selecting ferrous metals and alloys for specific application, you must analyze the followings:
- Dimensions: Outer diameter (OD), inner diameter (ID) overall length, and overall thickness are important dimensions.
- Production processes: Most materials are cast, wrought, extruded, forged, cold-finished, hot-rolled, or formed by compacting powdered metals or alloys. Electric arc furnaces are used to produce very clean metals and alloys with fewer inclusions and lower variability.
- Features: For improved weldability and the corrosion resistance Low carbon steels are used. For compressive strength, cold-worked steels are suitable.
In UNS, metals and alloys are assigned a lettered prefix followed by a five-digit number. For instance, carbon steels and alloy steels are categorized under the UNS G category and carry designations, such as UNS G10950.
Other Specifications for Ferrous Metals and Alloys
- AISI-SAE
- Casting grades
- European Norm (EN)
- U.S. Military specifications (MIL-SPEC)
Types of Ferrous Alloys
Various types of ferrous metals and alloys are available in the market:
- Carbon steels are ferrous alloys that contain carbon and small levels of other alloying elements, such as manganese or aluminum.
- Alloy steels contain low to high levels of elements such as chromium, molybdenum, vanadium and nickel.
- Stainless steels are highly corrosion resistant, ferrous alloys that contain chromium and/or nickel additions.
- Cast iron, a ferrous alloy, contains high amounts of carbon. Ductile iron, gray iron and white cast iron grades are types of cast iron.
- Cast steel alloy grades are made by pouring molten iron into a mold.
- Cast Iron Alloy and Iron Alloy are two major ferrous alloys used in most industrial applications.
Material suppliers provide ferrous metals and alloys in many shapes and forms:
- Semi-finished stock shapes are used for part fabrication. They are also suitable as feedstock for casting, forging, spinning and other forming processes.
- Common stock shapes include bars, rods, tubes, plates, strips, shims, spheres, foil, wire, billets, slabs, and blooms.
- Materials are also available as ingots, powders, fillers, and reinforcements.
Ferrous Alloys Casting
Companies often specialize in casting of ferrous alloys due to the requirement of specialized equipment for melting and pouring ferrous materials. Casting of ferrous materials is generally attained through means of shell casting, sand casting, or to a lesser extent investment casting.
In ferrous casting, the most commonly used metal materials, such as cast iron alloys and iron alloys including grey iron casting, ductile iron casting and steel iron casting.