In a tensile test this is the prescribed part of the cylindrical or prismatic portion of the test piece on which elongation is measured at any moment during the test. In particular, a distinction should be made between the following: ~ The original gauge length, i.e. the gauge length before the test is started. ~ The final gauge length – The gauge length after the test is completed and the test piece has fractured. The broken pieces are carefully fitted together to lie in a straight line so that it can be measured.
Coarsening of the grain structure that occurs under certain conditions of heating. It is generally undesirable and is deleterious.
A measure of the area or volume of grains in polycrystalline material. Grain size is reported in a number of ways 1. number of grains per unit of area or volume, 2. average diameter, 3. as a grain size number derived from area measurements and comparison with a standard chart.