Essential Principles of Metallurgy and Material Properties

Key Concepts in Metallurgy and Materials Science

• The higher the ideal critical diameter of steel, the lower its hardenability.
• The greater the hardenability of steel, the greater the hardness of martensite that forms upon quenching.
• The lower the specific heat of a bath, the more energetic the cooling it produces during tempering.
• Examples of transformations include diffusion and martensitic transformations.
• Standard heat treatment can result in a coarser grain size in steels compared to those annealed at the same temperature.
• Hadfield steel, with more than 1% carbon and 14% manganese, is an example of martensitic steel.
• Magnesium is the element that causes the graphitization of white cast irons.
• Standard heat treatment produces a coarser grain size than annealing.
• Aluminum is a highly formable material and reaches its maximum toughness at 500 °C.
• Iron, cobalt, and nickel are the three carbide-forming elements.
• The transformation of austenite to martensite is accompanied by a decrease in volume.
• The gradual elevation of the temperature of a steel workpiece to 650 °C after tempering is a process of martensite stabilization.
• The hardenability of steel depends on the cooling medium.
• Ledeburite is a chemical compound of iron and carbon, containing 4.3% carbon, and has a fixed melting point.
• Forging aluminum alloys generally contain a higher percentage of alloying elements than casting aluminum alloys.
• Interstitial Ledeburite is a congruent melting compound.
• The addition of cobalt to steel can help mitigate tempering brittleness.
• The most harmful impurities for bronzes are sulfur (S) and bismuth (Bi), which significantly affect mechanical properties, especially reducing elongation.
• Finishing of nitrided parts is performed after nitriding.
• The values of the coefficient of tempering severity are independent of the degree of agitation of the cooling medium.
• The main factors favoring the appearance of white cast iron are rapid cooling from the liquid phase and high silicon content.
• High-strength quenched and tempered alloy steels may contain more sulfur than cutting steels.
• Typical alloying elements in steels include silicon (Si) and molybdenum (Mo).
• Blue brittleness in steel occurs during aging at about 600 °C.
• Adding silicon to foundries favors the formation of nodular graphite instead of lamellar graphite.
• Elements silicon and nickel are carbide-forming.
• All alloys can be hardened by tempering.
• All tool steels are alloyed, often hypereutectoid, and may contain carbide-forming elements.
• A procedure to increase the yield strength of steels is the use of controlled rolling of HSLA steels to refine the grain size to ASTM values of 8.