Principles of Metal Working Processes

Abstract

Forging, dates back to ancient times, was associated with the village blacksmith. virtually all-ductile metals may be forged by first preheating the work piece to a forging temperature. The work piece can be a billet, a wrought bar, a cast or sintered ingot etc. The forging process can then be completed, by hammering the work piece to the desired shape. The design and control of metal working processes depend on the characteristic of the material, conditions ofmetal and tools interface, operating defor-mation mechanism and equipment used for working. 'Damascene technique' meant the forge welding of steel and iron or two types of steel. 'Damascus sword' was prepared by this technique. Forging has a marked beneficial effect on the metals being shaped. Their toughness and strength are improved because the process results in a beneficial orientation of the metal grain structure. The repeated hot working causes the metal to become more dense and the grain flow lines to follow the contour of the final compo-nent. The as cast structure is detrimental to the mechani-cal properties and therefore, it requires modification to improve the mechanical properties by refinement of micro-structure and homogenous distribution of phases. The generic bulk forming processes are forging, rolling, extru-sion and drawing. All these processes give a very high plastic deformation to the materials as the strain rate involved in these processes are considerable high. Forging is a high strain rate process where material is shaped under the effect of impact load or pressure.