Cold Working Lab

The primary focus of the lab was to understand the process and effects of cold working and annealing compared to a baseline sample. Cold working is a form of strain hardening in which metals are worked through the use of applied pressure, thereby making the metal harder[]. This applied pressure led to harder material by creating linear defects known as dislocations. The specific type of dislocation that occurred in this lab was an edge dislocation where an extra plane of atoms was inserted into the crystal structure. If enough pressure is applied on the material, a permanent deformation stemming from dislocations can occur, known as plastic deformation. The hardening of materials through the use of deformation in a material stems from the atomic structure of a metallic material.

Metals are held together by metallic bonding where electrons are shared amongst atoms so that a "sea" of electrons is created. This type of bonding is not only strong enough to keep the atom together, but because of a lack of bond directionality, dislocations are able to be created and moved without the entire molecule falling apart. …show more content…
Annealing refers to a heat treatment in which a material is exposed to an elevated temperature for an extended time period and then slowly cooled[]. The first degree of annealing is recrystallization, but further annealing grows the grains at the expense of smaller grains. Annealing in this lab was done for the purpose of recrystallization. This process equiaxed crystals through the nucleation and growth of new low stress and low dislocation density grains. This process causes the material to lose strength, thereby restoring