Standard Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings
4.1 Macroetching is used in the steel industry because it is a simple test that will provide information about the relative homogeneity of the sample. The method employs the action of an acid or other corrosive agent to develop the macrostructural characteristics of a suitably prepared specimen. The name implies that the etched surface is examined visually, or at low magnifications (usually <10??). 4.2 Macroetching will show: (1) variations in structure such as grain size, dendrites, and columnar structure; (2) variations in chemical composition such as segregation, coring, and banding; and, (3) the presence of discontinuities such as laps, seams, cracks, porosity, bursts, pipe. and flakes.
