Author: Haroon Khalil

Abrasives are hard, non-metallic, sharp edged, and irregular shaped materials used to remove small amount of materials by cutting action. It may be used in bonded form or as free particles. It is employed in grinding, polishing, super finishing, buffing, and honing operations. Commonly used abrasives are alumina (Al2O3), silicon carbide (SiC), cubic boron nitride…

Common organic materials are plastics and synthetic rubbers which are termed as organic polymers. Other examples of organic materials are wood, many types of waxes and petroleum derivatives. Organic polymers are prepared by polymerization reactions, in which simple molecules are chemically combined into long chain molecules or three-dimensional structures. Organic polymers are solids composed of…

These substances are composed of metals other than iron. However, these may contain iron in small proportion. Six non-ferrous materials are available in sufficient quantity reasonably at low cost and used as common engineering metals. These are aluminium, tin, copper, nickel, zinc, and magnesium. Some other non-ferrous metals, about 14 in number, are produced in…

In ferrous materials the main alloying element is carbon (C). Depending on the amount of carbon present, alloys will have different properties, especially when the carbon content is either less/higher than 1.5%. This amount of carbon is specific as below this amount of carbon, material undergoes eutectoid transformation, while above that limit ferrous materials undergo…

Common engineering materials may be classified into one of the following seven groups: Metallic materials are broadly of two kinds—ferrous and non-ferrous materials. Ferrous materials are those in which iron (Fe) is the principal constituent. All other materials are categorized as non-ferrous materials.

The behaviour of a material is also dependent on the rate at which the load is applied. For example, low-carbon steel shows a considerable increase in yield strength with increasing rate of strain. In addition, increased work hardening occurs at high strain rates. This results in reduced local necking, hence, a greater overall material ductility…

Hardness means as the resistance to penetration. Testing for hardness can be divided into three categories: Scratch tests involve comparatively scratching progressively harder materials. Mohs hardness scale is used for the test. Diamond, the hardest material, is assigned a value of 10. Decreasing values are assigned to other minerals, down to 1 for the soft mineral,…

Hook’s law: Hook’s law states that stress and strain are proportional to each other under elastic limit. Originally, Hooke’s law specified that stress was proportional to strain but Thomas Young introduced a constant of proportionality which is known as Young’s modulus. Further, this name was superseded by modulus of elasticity. where E is modulus of elasticity, σ is stress, and…

The important mechanical properties are listed below: