A simple metallographic techniques for revealing austenite grain boundaries in CK45 steel

CK45 steel is medium carbon steel that has a wide range of applications in the production of widely used parts such as shafts, gears, axles, crankshafts, forging, rails, etc. Austenitizing is the first step in most heat treatment processes for steel. Revealing austenite grain boundaries is very important because the austenite grains have a significant influence on steels properties. Because no research has been done on the detection of prior-austenite grain boundaries of CK45 steel, our main aim in this paper is revealing the prior-austenite grains of this steel. We investigated two methods of chemical etching and oxidation etching to reveal prior-austenite grains boundaries of CK45 steel. Samples of CK45 with different structures(martensite, bainite, ferrite-perlite) steel were examined, and the optical microscopic images showed that the boundaries of the austenite grains were well visible with oxidation etching while with the chemical etching method, only the structure of the steels was determined.