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Engineering Metallurgy Study Notes

• Material study in engineering aims to understand material behavior.

• Wood exemplifies a natural material.

• Ductility describes a material's ability to deform without breaking.

• Metallic bonds hold atoms together in metals.

• Toughness is the material property indicating the amount of force a material can withstand without breaking.

• A "composite material" is composed of a mixture of two or more substances.

• Hardness is the material property related to a material's resistance to being scratched.

• Tensile testing involves applying an increasing load until the material breaks.

• Scanning electron microscopes use electrons for imaging instead of visible light.

• The Rockwell hardness test measures penetration depth on hardened steel.

• Brinell hardness test measures the depth of penetration of a hardened steel ball

• A pyramid-shaped diamond indenter is used in the Vickers hardness testing method.

• Body-centered cubic structures have a packing efficiency of 0.68.

• Glass serves as a common example of a crystalline solid.

• Bamboo and wood are natural composite materials.

• Face-centered cubic (FCC) structures have the highest packing factor.

• Alcohol is NOT a typical etchant for sample preparation.

• The Brinell hardness test is most suitable for brittle materials.

• Magna Flux testing is based on electromagnetic field interaction.

• The eutectic point is where a metal alloy changes from liquid to solid on a phase diagram.

• Major engineering materials include metals, ceramics, polymers, and composites.

• The Brinell testing method uses a 10mm steel ball for testing.

• The Vickers hardness test uses a pyramid penetrator with a 136° included angle.

• The inspection process 'magnaflux' cannot detect laps.

• The smallest, repeating portion of a crystal is called a unit cell.

• Tetragonal Bravais lattices do not have all right angles.

• Six parameters are used to characterize a unit cell.

• Zinc has a hexagonal close-packed (HCP) crystal structure.

• The axial relationship of a monoclinic crystal system is a ≠ b ≠ c.

• The atomic packing factor of a body-centered cubic (BCC) structure is 0.68.

• Y iron has a body-centered cubic crystal structure.

• A triple point exists when all three states of matter are in equilibrium.

• Phase transformation involves nucleation and growth.

• Aluminum oxide is used for fine polishing.

• Ductility results in a more fine-grained structure.

• Chlorine-based solvents serve as penetrating liquids in liquid penetration tests.

• Eddy current testing is a non-destructive test that detects composition changes.

• High-frequency sound waves are used to detect flaws in castings via ultrasonic inspection.

• Radiography for casting inspections uses X-rays.

• The axes system of a cubic crystal system has a = b = c, α = β = γ = 90°. The Vicker's hardness test differs from the Brinell hardness test with the type of indenter.

• Applying a 2000kg load with a 250 square millimeter impression yields a Brinell number of 8 kg per square millimeter.

• A cooling curve represents how temperature changes as the metal solidifies.

• The composition axis in a binary equilibrium diagram provides information about the percentage of each element in an alloy.

• The Phase Rule helps determine the number of phases in a system at equilibrium.

• The components are completely soluble in each other in all proportions for an Isomorphous System.

• The triple point of water is 0.0098 degrees Celsius.

• Gibbs phase rule is defined as F = C - P+2.

• The eutectoid reaction occurs at the eutectoid composition.

• The Iron-Carbon equilibrium diagram helps in understanding the various phases and phase transformations of steel at different temperatures.

• At the eutectoid point in the Iron-Carbon equilibrium diagram, decomposition of austenite to pearlite occurs.

• In a T-T-T diagram, T stands for temperature.

• Austenite is found in the Iron-Carbon equilibrium diagram above the eutectoid composition.

• Austenite has a face-centered cubic (FCC) crystal structure.

• The melting point of iron is 1538 degrees centigrade.

• The iron-carbon phase diagram is binary.

• A binary phase system has 2 components.

• Steels containing 0.8% carbon are called eutectoid.

• A mixture of austenite and cementite is called Bainite.

• The eutectic point occurs at 4.3 weight % carbon on the iron-iron carbide phase diagram.

• Cooling austenite of eutectoid composition results in pearlite formation occur at 723°C.

• Melting temperatures of various phases cannot be obtained using a phase diagram.

• Liquid + Solid 1 → Solid 2 denotes a Peritectoid reaction.

• For a 53% Ni Cu-Ni alloy cooled to 1300°C, percentages of liquid and solid are 35% and 65%.

• For a 34.6% Pb-Sn alloy cooled below the eutectic temperature, there is 30% proeutectic and 70% eutectic mixture.

• Time-temperature transformation diagrams are used for any alloy, including steel.

• When the transformation temperature of steel is in the range of 500 °C to 750 °C, the resulting phase pearlitic.

• When the transformation temperature of steel is in the range of 300 °C to 550 °C, the resulting phase is martensitic.

• When the transformation temperature is in the range of 100°C to 300°C the resulting phase will be martensite.

• The peritectic reaction at 1495°C in the Fe-C diagram is L (0.53% C) + δ(0.09% C) → γ(0.8 % C)

• The eutectoid reaction at 727°C in the Fe-C diagram is γ(2.1 % C) → α (0.025% C) + Fe3C (6.67% C).

• A slowly cooled eutectoid steel from 750°C to just below 727°C consists of 85.4% ferrite and 14.6% cementite.

• Malleable cast iron is stronger than gray cast iron.

• White cast iron is also known as Chilled cast iron.

• Carbon content in white cast iron generally varies from 2 to 3.6%.

• Cast iron is composed of tough materials,

• The primary differentiating constituent between low, medium, and high carbon steels is carbon content itself.

• High-speed steel (HSS) primarily employed in machine tool cutting.

• Low carbon steel is commonly used in crankshafts due to its high strength and fatigue resistance.

• The designation standard used for steel specifications in India is BIS.

• Silicon composition in cast iron is 4.5-5%.

• Gray cast iron contains carbon from 1.2% to 2%.

• Alloys mainly consisting of Iron and Carbon are plain carbon steels.

• Stainless steel is NOT a type of plain carbon steel.

• Alloying elements are added to steel to improve mechanical properties.

• Austenitic stainless steel is most commonly used in kitchen utensils.

• Chromium stands as the primary element used for making the stainless-steel alloy.

• plain carbon steels are mainly consisting of Iron and Carbon.

• Carbon composition in medium carbon steels is 0.25%- 0.6%.

• If the iron surface contains graphite, it is known as spheroidal graphite.

• Spheroidal graphite cast iron cannot be machined.

• Nickel increases corrosion resistance, Refines grain structure,

• The primary element used to make stainless steel is chromium.

• Stainless steels with little carbon and no nickel are called Ferritic stainless steel

• Amount of chromium normally added in steel to be called as stainless steel is 10-30%.

• High carbon steel contains 0.70% to 2.2% carbon.

• Applications of Ferritic stainless steels consist of pumps and valve parts,

• As carbon increases in steel, hardness decreases.

• Engine blocks are mostly manufactured by using grey cast iron.

• Cerium is used as an alloying element to deoxidize steels.

• High-carbon steel is used when high hardness is desired and ductility is not crucial.

• Applications of high-carbon steel are in Machine tools, leaf and coil springs.