ETCHING SOLUTION FOR MAKING AUSTENITE GRAIN BOUNDARY OF STEEL APPEAR

摘要

PURPOSE:To obtain an etching soln. for making the austenite grain boundaries of steel appear by mixing an aqueous picric acid soln. having a specified concn. with specified amounts of a surfactant and an alkali metallic sulfate or chloride so that the resulting etching soln. is made applicable to any steel material. CONSTITUTION:An aqueous picric acid soln. having 1% W/V - saturation concn. is mixed with 0.5-10% W/V surfactant and 0.01-1% W/V alkali metallic sulfate or chloride to obtain an etching soln. for making the austenite grain boundaries of steel appear. The surfactant removes fats and oils sticking to the surface of a material to be treated to clean the surface. The alkali metallic sulfate or chloride is used to facilitate the etching of grain boundaries.