Metallurgy and its application to produce new engineering materials play a very important role in workshop practice. One of the most important metallurgical application is the development of jet engines for aircrafts where the need for alloys that can withstand high temperatures is critical. In palm oil mills, the main requirement are confined to materials often in the form of alloys possessing the properties of corrosion resistance, erosion, strength and other requirements. There are continuously being manufactured to suit the different engineering requirements. It will therefore be useful for the workshop crew to gain some insight into the properties of such materials. This article was originally prepared and published in the Engineering New Issue No. 32 by the late Ir Jack Maycock to improve the technical knowledge of the workshop foreman, artisans and fitters. It will also serve the maintenance engineers as a reference material. The maintenance engineers are encouraged to use the material contained in this article to give lectures to their maintenance team in a simple language so that they understand the fundamental principles. They can be tested orally to gauge the knowledge they have gained and certificates issued by the manager or the authorised person.