Hot working does not produce strain hardening. Hence no increase in either yield strength or hardness occurs. In addition yield strength decreases as temperature increases and the ductility improves.
Hot working can be used to drastically alter the shape of metals without fear of fracture and excessively high forces.
Elevated temperatures promote diffusion that can remove chemical inhomogeneties; pores can be welded or reduced in size during deformation.
The dendritic grain structure, small gas cavities and shrinkage porosity formed during solidification in large sections can be modified by hot working to produce a fine, randomly oriented, spherical-shaped grain structure which results in a net increase in strength, ductility and toughness.
Hot working results in reorientation of inclusions or impurity particles in the metal with the result that an impurity originally oriented so as to aid crack movement through the metal can be reoriented into a “crack arrestor” configuration.
