ASTM A561 – Standard Practice for Macroetch Testing of Tool Steel Bars
This practice covers macroetch testing used for evaluating the quality of tool steel bars. This test shall be used as a quality control and inspection test to reveal by deep acid etching, the macrostructure in specimens cut from bars and to show the presence, absence, and severity of the following internal, surface, or subsurface conditions: pipe, bursts, carbide or alloy segregation, nonmetallic inclusion concentrations, porosity, cracks or thermal flakes, seams, laps, ingot corner segregation, pinholes, foreign material, and ingot pattern. Macroetching may be performed in a vessel of borosilicate glass, porcelain, corrosion-resistant metals, or some other acid resisting material. The etching reagent, specimen sampling, specimen preparation, and testing procedure including etching temperature, etching time, and macroetching technique are detailed.
1.1 This practice for macroetch testing has been found to be a useful and reliable method for evaluating the quality of tool steel bars. It is used as a quality control and inspection test to reveal by deep acid etching the macrostructure in specimens cut from bars and to show the presence of such conditions as pipe, cracks, porosity, segregation, or foreign material. The etched surface is generally examined visually, but magnification up to about 10× is occasionally employed.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.