Material Science and Engineering

Hardness measures a material's resistance to permanent deformation and wear, increased by cold working or heat treatment. It covers Brinell, Rockwell, and Vickers tests based on surface indentation.

Learn about the Vickers hardness test and its relation to Brinell, using a pyramid diamond cone; include micro hardness (Knoop) and shore scleroscope methods for thin, small parts.

Dynamic properties describe how materials respond to rapidly changing loads, differing from static properties. Charpy tests measure impact energy absorbed via elastic or plastic deformation, illustrating ductile versus brittle behavior.

Analyze how temperature, carbon content, grain size, and orientation shape impact energy and ductile-to-brittle transitions in FCC and BCC materials under dynamic loads.

Fatigue causes sudden cracks in materials under fluctuating dynamic load, typically initiating at surface flaws and propagating with cycles; stress concentration, surface finish, and compressive surface stress govern fatigue life.

Understand how constant load at elevated temperature causes time-dependent creep and progressive deformation. Explore how creep resistance, melting point, modulus, and grain size shape engine turbine blade performance.

Explore non-destructive testing methods to detect surface and internal defects, such as visual inspection, liquid penetrant testing, magnetic particle inspection, radiography, ultrasonic inspection, acoustic emission, and leak testing.

Ultrasonic testing uses sound waves with a transducer and receiver to locate defects and measure thickness; radiographic testing uses density changes to reveal defect size and location.

Classify engineering materials into metallic, polymeric, and ceramic groups and show how chemical composition and heat treatment shape properties, including cast iron and steel in ferrous metals.

Explore how plain carbon steel, an iron and carbon alloy, achieves different strength and hardness through carbon content and heat treatment, while ductility falls and quenching risks distortion.

Alloy steels improve strength, hardenability, and corrosion resistance by elements such as chromium, nickel, molybdenum, boron, and manganese, while manganese prevents iron-sulfide formation at grain boundaries, boosting ductility and weldability.

Stainless steel, or corrosion resistance steel, gains superior corrosion resistance from a chromium oxide layer; ferritic, martensitic, and austenitic types differ in chromium content and nickel additions.

Explore nonferrous metals such as aluminium, copper, zinc, titanium, nickel, and magnesium, highlighting their corrosion resistance, high thermal and electrical conductivity, low weight, and easier fabrication than steel.

Explore refractory metals' properties and applications, including nickel, tungsten, and molybdenum, highlighting high temperature strength, creep and corrosion resistance, and use in jet engines, gas turbines, rockets, and nuclear applications.

Explore plastics and ceramics in material science, detailing design flexibility, high strength and toughness, electrical and thermal insulation, low cost and weight, and contrast thermosets with thermoplastics and ceramics' properties.

Corrosion is deterioration from chemical attack by environments, with oxidation at the anode driven by a potential difference between anode and cathode, including uniform, crevice corrosion, pitting, and galvanic corrosion.

Review key mechanical properties and tests, including tensile outcomes (yield point, modulus of elasticity, UTS, fracture point) and hardness; cover fatigue life, elevated-temperature behavior, and heat treatment for engineering materials.

Explore how heat treatment and cold working modify steel properties by altering microstructure, with controlled heating, holding time, and cooling rate determining strength, hardness, and ductility.

Examine how the iron-carbon equilibrium diagram links carbon content and temperature to ferrite, pearlite, cementite, and austenite, with the line at 723°C; steel below 2% carbon, cast iron above 2%.

Apply heat treatment by heating above 723 centrigrade degree to reach austenite and achieve equilibrium before controlled cooling. Rapid cooling can produce martensite, increasing strength and hardness.

The TTT diagram shows how cooling rate during heat treatment shapes steel structure, hardness, and strength, with pearlite, bainite, and martensite outcomes.

Illustrate a time-temperature-transformation diagram for mild steel (0.8% carbon) by heating to about 900 celsius, soaking, and quenching with molten salt and water to yield martensite-rich structures.

Understand how carbon content and alloying elements such as boron, chromium, magnesium, and molybdenum, quenching practices and cooling rates govern hardenability, grain size, surface and core structure, distortion, and toughness.

The Jominy test shows how cooling rate from different media affects hardness along a specimen, measuring depth of hardening from the quench and surface through standard figures.

Explore heat treatment after casting, welding, or hot working to control heating and cooling, modify hardness and strength, reduce internal stress, and obtain desired microstructures.

Apply spheroidizing annealing to refine grain size, reduce stress, and improve toughness and machinability in steel. Through plastic deformation, it forms a spherical structure, boosting formability and tool life.

Apply recrystallization annealing to relieve stresses from plastic deformation, restore original grain structure, and control grain size through recovery, recrystallization, and grain growth at varying temperatures.

Apply stress relief annealing to reduce residual stress in metal components by controlled heating to 550–650 or 600–750 degrees and careful cooling, improving strength, distortion control, and corrosion resistance.

Full annealing relieves internal and residual stress, reduces brittleness, and improves machinability, using two temperature ranges by carbon content with controlled furnace cooling to yield a uniform, segmented final structure.

Normalizing holds the material at elevated temperature for a shorter time than full annealing to refine grain size, achieve uniform properties, and reduce costs.

Explore the hardening process by heating steel to critical temperatures. Quench in water, oil, or a molten bath; manage tempering, decarbonisation, oxidation, furnace types, and holding time.

Control cooling rates through quenching and tempering to tailor steel hardness, toughness, and residual stresses, using surface and center cooling and structural transformations.

Explore cooling media such as water, brine, oil, and cryogenic liquids to control quenching rates and the temperature difference between surface and center in steel, addressing bubbles and oxidation.