Effect of grain size on properties of metals

          A grain is a crystal with almost any external shape, but with an internal atomic structure based on the space lattice with which it was born.

          The mechanical properties of metals that obtain maximum strength depends upon the arrangement of the grains, their shape and especially their size. Grain size directly controls the extent of slip interference by adjacent grains and strength, toughness, ductility and fatigue of metals thus affected. The grain size is controlled by several factors out of which temperature and time of heating are important.

The important effects of grain size are given below:

1. Fine grained structure has higher strength than coarse grained structure.
2. Fine grain provides better resistance to cracking, and better machine finish.
3. Coarse grains make surface rough and make metal less tough.
4. Coarse grained metal is difficult to polish.
5. Coarse grained structure has a better workability than fine-grained structure.
6. Coarse grained materials at high temperature exhibit better creep resistance than grained one.