Generally, copper and copper alloys have a specific and predictable recrystallization grain growth response to annealing. After cold-working to a specified reduction in thickness, the copper or copper alloy can be annealed to any of several grain size ranges.
The most commonly specified nominal grain sizes in annealed tempers are: 0.015 mm, 0.025 mm, 0.035 mm, 0.050 mm, 0.070 mm, and 0.100 mm.
Some alloys, such as C26000, cartridge brass can be annealed to a number of grain size ranges, including very small sizes. Because such grain sizes are difficult to measure, tensile strength is the preferred measurement for these tempers. The tensile strength ranges produced by annealing to these very small grain sizes are similar to the tensile strengths resulting from cold rolling reduction in thickness. As a result, these temper are referred to as "annealed-to-temper" and can be expressed as "annealed-to-temper ¼ hard" or "annealed-to-temper ½ hard." This process is used because the fine grain size produced gives a smooth surface after forming, while the lower yield strengths and higher elongations provide excellent formability.