Work hardening, also known as strain hardening, is the process by which a material's load-bearing capacity (strength) increases during plastic (permanent) deformation. This characteristic is what sets ductile materials apart from brittle materials.[1] Work hardening may be desirable, undesirable, or inconsequential, depending on the application.
This strengthening occurs because of dislocation movements and dislocation generation within the crystal structure of the material.[2] Many non-brittle metals with a reasonably high melting point as well as several polymers can be strengthened in this fashion.[3] Alloys not amenable to heat treatment, including low-carbon steel, are often work-hardened. Some materials cannot be work-hardened at low temperatures, such as indium,[4] however others can be strengthened only via work hardening, such as pure copper and aluminum.[5]
^Van Melick, H. G. H.; Govaert, L. E.; Meijer, H. E. H. (2003), "On the origin of strain hardening in glassy polymers", Polymer, 44 (8): 2493–2502, doi:10.1016/s0032-3861(03)00112-5