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• Steel is an alloy of iron and carbon with the carbon being restricted within certain concentration limit.
• Steel is the most prevalent metal used in engineering application due to the abundance of iron ore.
• Carbon steels are simply alloys of iron and carbon, with carbon being the major strength agent.
• Plain carbon steels are the non-sulfurized carbon steels.
• Medium-carbon steel is the steel having 0.30 to 0.70 % carbons.
• High-carbon steel is the steel having 0.70 to 1.40 % carbon.
• Free machining steels are resulfurized carbon steel.
• Alloy steels are steels that have significant addition of any element other than carbon.
• A steel that exceeds one or more of the following limits: manganese, 1.65% silicon 0.60%, copper, is also considered as alloy steel according to the definition of the Steel Product Manual.
• Low-alloy steels are those with less than 8.0 % total alloying ingredients.
• High-alloy steels are those with more than 8.0 % total alloying ingredients.
• U.S steel producer defined tool steel as carbon or alloy steels capable of being hardened and tempered.
• The three main performance criteria of tool steels are: Wear resistance, Hot hardness, and Toughness.
• Hot hardness refers to the ability of a steel to resist softening at high performance.
• Another term for hot hardness is red hardness.
• Stainless steels are alloy of iron, chromium and other elements that resist corrosion from many environments.
• For steel to qualify the stainless prefix, it must have at least 10% chromium.
• Ferritic stainless steels contain chromium in the range of 16% to 20% and have carbon content less than 0.2%.
• Martensitic stainless steels contain chromium in the range of 12% to 18% and have carbon content as high as 1.2%.
• Austenitic stainless steels have at least four major alloying elements, namely iron, chromium, carbon and nickel.
• The chromium content ranges from 16% to 26%.
• Gray iron is a high-carbon, iron-carbon-silicon alloy and is the most common type of cast iron.
• White iron is a type of cast iron that has a hard as-cast structure and difficult to machine.
• Malleable iron is a type of cast iron with its structure altered by thermal treatments to give it measurable ductility and increased tensile strength.
• Ductile iron is similar to malleable iron in ductility is achieved by ladle additions and contains nodular or spheroidal graphite.
• Mottled iron contains both cementite and graphite and is between the gray and white irons in composition and performance.
• Grade of Gray Cast Iron Alloys:
• Effects of Elements in Cast Iron: