Bolting steel is cast as ingots or strands. ASTM A962 requires enough discard from each ingot that the bars carry no pipe or segregation that would unfit them for bolting. It makes the steel producer check internal quality by macroetch to ASTM E381, one test per heat and size, and A193 and A194 certificates report the macroetch result for carbon and alloy steels.
Forging moves the metal, and the etch shows where it went. Forge shops use macroetching to set up forging practice and die design (ASTM E340). Forging specifications offer it as a supplementary requirement: A182 S1 sections a sample forging to show flow lines and internal imperfections, and A668 S2 checks the flow lines when special forging techniques are ordered.
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model dataMethod from ASTM E381 (bars, billets, blooms and forgings) and ASTM E340 (flow lines in forgings); one macroetch per heat and size, and the S2-R2-C3 limit for ingot-cast bolting steel, from ASTM A962; the 1:1 hydrochloric acid and water etch is the most common for steel. The bar, saw, grinder, acid bath and bolt blank are generic examples, and the bar size is not a stated figure. The etched features and the graded photographs are schematic, not copies of the standard's plates. Reagent, temperature, time and surface preparation are agreed between maker and buyer, so no etch temperature, time or slice thickness is shown; the cut and the etch are time-lapsed.
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