Ferrous Metals and Iron Alloys

Ferrous metals and alloys are iron-based materials that are used in a wide variety of industrial applications. Examples include carbon steels, alloy steels, stainless steels, tool steels, cast iron, cast steel, maraging steel, and specialty or proprietary iron-based alloys. Many materials meet the compositional standards of the Unified Numbering System (UNS), a specification established by the American Society for Testing and Materials (ASTM), the Society of Automotive Engineers (SAE), and metal trade associations such as the American Iron and Steel Institute (AISI) and the Aluminum Association (AA). The UNS assigns metals and alloys a lettered prefix and a five-digit number. For example, carbon steels and alloy steels belong to the UNS G category and have designations such as UNS G10950. AISI-SAE is another common specification for ferrous metals and alloys. Other standards include casting grades, European Norm (EN), and U.S. military specifications (MIL-SPEC). QQ and QQS prefixes are used to designate specific MIL-SPEC metals.  

There are many types of ferrous metals and alloys. 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. There are three basic types of products: austenitic stainless steels, ferritic and martensitic stainless steels, and specialty stainless steels and iron superalloys. Tool steels are wear resistant, but difficult to fabricate in their hardened form. Specific grades are available for cold-working, hot-working, and high speed applications. Cast iron is a ferrous alloy with high amounts of carbon. This category includes ductile iron, gray iron and white cast iron grades. Cast steel alloy grades are made by pouring molten iron into a mold. AISI-SAE H-steels are produced to specified hardenability bands. UNS D steels have specified mechanical properties. High strength low alloy (HSLA) steels, iron-based superalloys, metal matrix composites, pure alloys, and clad or bimetal materials are also available.

Suppliers provide ferrous metals and alloys in many stock shapes and forms. Semi-finished stock shapes are suitable for part fabrication. They are also used as feedstock for casting, forging, spinning and other forming processes. Common stock shapes and forms for ferrous metals and alloys include bars, rods, tubes, plates, strips, shims, spheres, foil, wire, billets, slabs, and blooms. Materials are also supplied as ingots, powders, fillers, and reinforcements. There are two basic types of anodes. Plating anodes are in used in plating or electroplating processes. Sacrificial anodes are used to protect steel or other metal structures from corrosion.  

Selecting ferrous metals and alloys requires an analysis of dimensions, production processes, and features. Outer diameter (OD), inner diameter (ID) overall length, and overall thickness are important dimensions. Most materials are cast, wrought, extruded, forged, cold-finished, hot-rolled, or formed by compacting powdered metals or alloys. Some ferrous metals and alloys are modified with boron or free of lead and selenium. Others are hardened by air, oil, or water. Electric arc furnaces are used to produce very clean metals and alloys with fewer inclusions and lower variability. Low carbon steels offer improve weldability and the corrosion resistance. Cold-worked steels have good compressive strength and wear resistance under room temperature conditions. Precipitation hardening (PH) adds chromium and nickel to stainless steels that undergo solution treating and aging. Austenitic stainless steels can be hardened by cold-working, but not by heat treatment. Ferritic stainless steels cannot be hardened by heat treatment, and only moderately hardened by cold-working. Some martensitic steels can be heated to tensile strengths that exceed 200,000 psi (1379 MPa).

• Stainless Steel
  Stainless steels are highly corrosion resistant, ferrous alloys that contain chromium and/or nickel additions. There are three basic types of products: austenitic stainless steels, ferritic and...
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• Rust Preventative Coatings
  Rust preventative coatings are designed to minimize rust or iron alloy corrosion when applied directly to ferrous metal such as carbon or alloy steels. They protect against rust by preventing moisture...
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