Materials selection, properties, and processing

Materials Selection and Properties

Properties of materials are the qualities that define how a material behaves when subjected to external factors such as heat, force, and pressure. They generally fall into four categories: mechanical, thermal, electrical, and chemical.
Mechanical properties include hardness, tensile strength, compressive strength, ductility, malleability, and toughness. These properties dictate how a material responds to forces such as tension (pulling apart), compression (pushing together), and shear (sliding past each other).
Thermal properties, such as thermal conductivity, thermal expansion, and specific heat capacity, tell us how a material behaves when subjected to changes in temperature.
Materials differing in electrical properties are often used in the construction of electrical circuits. These properties include electrical resistance, electrical conductivity, and dielectric strength.
Chemical properties are of great significance in materials exposed to various environmental conditions. These properties include corrosion resistance and chemical stability.
In engineering, the selection of materials is done based on the desired properties for a specific application. Factors influencing material selection might include cost, availability, ease of fabrication, and environmental impact, in addition to the necessary mechanical, thermal, electrical, and chemical properties.

Materials Processing

In materials engineering, processing refers to the series of steps or “unit operations” used in converting raw materials into finished or semi-finished products. It includes practices such as casting, welding, machining, and heat treatment.
Casting is a manufacturing process where a liquid material is typically poured into a mould, which contains a hollow cavity of the desired shape, and then allowed to cool and harden.
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence or commonly referred to as fusion. This is achieved by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint.
Machining is a broad term to describe removal of material from a workpiece. It encompasses processes such as drilling, turning, milling, and grinding.
Heat treatment is a process used to change the physical or chemical properties of a material through heating and cooling it to extreme temperatures. This is done to improve certain characteristics such as hardness, toughness, and ductility.

Understanding materials selection, properties, and processing is a critical part of engineering. It determines the functionality, reliability, and longevity of engineering products and components.