Ferrous Materials and Heat Treatment Quiz

Overview of Ferrous Materials and Heat Treatment of Metals

• Ferrous materials are classified as containing iron as the principal constituent, with steel being the most extensively used material for machine components.
• Steel contains carbon up to 2.0% and is generally produced by crucible furnace or electric furnace. It is tough, malleable, and can be forged, with more tensile strength than other metals.
• Plain carbon steel, also known as mild steel, is the most common form of steel due to its relative low price and acceptable material properties for many applications.
• Alloy steel is a combination of iron, carbon, and other alloying elements. It is rustproof, harder and tougher, and can be uniformly hardened, but is hard for machining and nonmagnetic.
• The carbon percentage present in steel ranges from low carbon steel (0.05-0.15%) to ultra-high carbon steel (1.0-2.0%).
• Impurities present in steel include sulfur (0.02-0.05%), phosphorous (0.02-0.05%), silicon (0.05-0.20%), and manganese (0.30-1.50%).
• The degree of hardness, melting point, and ease of forging and forge welding are affected by the carbon content in steel.
• The AISI and SAE designation of steels include a four or five-digit number indicating the percentage of carbon and principal alloying element present in the steel, with a prefix indicating the method of producing the steel.
• Heat treatment of metals involves several processes such as annealing, normalizing, quenching, tempering or drawing, case hardening or carburizing, cyaniding, nitriding, surface hardening, and spheroidizing.
• Annealing involves heating the metal to a temperature slightly above the critical temperature and then cooling slowly to produce an even grain structure, reduce hardness, and increase ductility.
• Normalizing removes the effects of any previous heat treatment and produces a uniform grain structure before other heat treatments are applied to develop particular properties of metal.
• Case hardening, cyaniding, nitriding, and surface hardening are processes used to alter properties within the surface or localized area of a metal, while spheroidizing softens higher carbon steels and allows more formability.