Materials Science Flashcards

Flashcards about Materials Science focusing on the Iron-Carbon Phase Diagram, Heat Treatment of Ferrous Alloys, and Heat Treatment of Nonferrous Alloys and Stainless Steel.

What is an Iron-Carbon Phase Diagram?

A diagram representing the phases of iron and carbon alloys at different temperatures and compositions.

What is Heat Treatment?

Heating and cooling alloys at various rates to modify microstructures and mechanical properties.

Name examples of mechanical properties that can be influenced by phase transformations during heat treatment.

Strength, hardness, ductility, toughness, and wear resistance.

What factors does the effect of thermal treatment depend on?

Particular alloy, alloy composition, alloy microstructure, degree of prior cold work, and rates of heating and cooling.

What is the difference between fine and coarse pearlite?

Fine pearlite has thin, closely packed lamellae, while coarse pearlite has thick, widely spaced lamellae.

What type of cooling rate leads to fine pearlite?

High cooling rates (e.g., air cooling) lead to fine pearlite, while slow cooling rates (e.g., furnace cooling) result in coarse pearlite.

How is spheroidite formed?

Heating pearlite to just below the eutectoid temperature and holding it there for an extended period.

What are the resulting properties of spheroidite?

Higher toughness and lower hardness than pearlite structure.

What is Bainite?

A fine microstructure consisting of ferrite and cementite, similar to pearlite but with a different morphology.

What properties does bainitic steel generally have compared to pearlitic steels?

Stronger and more ductile than pearlitic steels at the same hardness level.

How is Martensite formed?

Formed when austenite is cooled at a high rate, transforming its FCC structure into a body-centered tetragonal (BCT) structure.

What are the mechanical properties of Martensite?

Extremely hard and brittle due to limited slip systems and interstitial carbon atoms.

What is Tempering?

Heating martensite to reduce hardness and increase toughness.

What does tempered martensite decompose into?

A two-phase microstructure consisting of BCC alpha ferrite and small particles of cementite.

How can the transformation of austenite into pearlite be best presented?

Isothermal transformation (IT) or Time–temperature–transformation (TTT) diagrams

In the TTT diagrams what is done to start with a state of austenite?

Raising the TTT curve to a very high temperature to start with a state of austenite.

What is hardenability?

The capability of an alloy to be hardened by heat treatment.

What is hardness?

The resistance of a material to indentation or scratching

What are case-hardening processes?

Carburizing, carbonitriding, cyaniding, nitriding, boronizing, flame hardening, induction hardening, laser-beam hardening.

What is annealing?

Heating a workpiece to a specific temperature, holding it, and cooling it to increase ductility, reduce hardness and strength, or modify the microstructure.