In the past designers were unable to account for structural inhomogeneity, surface defects, etc., and it was considered good practice to use large factor of safety. This has been discouraged by aircraft and automotive industries. They demanded new high-strength and light weight alloys. Rising energy costs has demanded power industry to improve the cycle efficiency in order to achieve low generation cost. To substantially gain improvements in efficiency, it is necessary to increase the steam pressures and temperatures leading to requirement of materials to withstand high pressure and temperatures. All these lead to rapid research and development in the field of metallurgy and the demand keeps on increasing everyday. Thus metallurgy has become a very important subject in the field of engineering.
Metallurgy is the science of metals. It is broadly divided in two large groups. Process or extractive metallurgy is the science of obtaining metals from their ores, including mining, concentration, extraction and refining. Physical metallurgy is the science concerned with the physical and mechanical characteristics of metals and alloys. Physical metallurgy studies the properties of metals and alloys affected by following three variables.
Chemical composition - the chemical constituents of the alloy.
Mechanical treatment - any operation that causes a change in shape like rolling, drawing, forming, machining, etc.
Heat treatment - the effect of temperature and rate of heating and cooling.
As the physical metallurgy is concerned with the physical and mechanical characteristics of metals and alloys, its knowledge is very important for mechanical engineers working in the field of design and maintenance. Maintenance engineers will find the knowledge useful for development of spare parts by reverse engineering, understanding of welding technology and root cause analysis of failures.
