A novel etchant for revealing the prior austenite grain boundaries and matrix information in high alloy steels

To observe the prior austenite grain (PAG) boundaries in high-alloy steels, a novel etchant composed of oxalic acid, hydrogen peroxide, sodium bisulfite, and water has been developed. Etching with this system successfully revealed both the grain boundaries and the deformation bands within grains in high Co–Ni martensitic alloy steels. The carbon content of the alloys used in the test program varied from 0.23% to 0.35%, the cobalt content was in the range 9–13%, and the nickel content was in the range 8–11%. The specimens were austenitized at temperatures in the range 900–1200 °C. The rolling temperatures ranged from 700 °C to 1000 °C. The grain sizes in these alloys and those containing titanium were clearly revealed by optical microscopy following application of the new etchant.