Abstract��In this thesis, The author made the basic principle of chemical corrosion, With the aid of a water-heater controllable in both temperature and time, various chemical etching methods were investigated to reveal austenite grain boundaries in Micro-alloy steel containing rare earth under different heat-treatment processes. The results show that the chemical etching method using 70mL distilled water, 2.5g of picric acid and and one drop of Xylene and one drop of hydrochloric acid and one drop of Hydrofluoric acid and a bit of Seagull brand paste shampoo and very little Copper chloride��can clearly reveal the austenite grain boundary, and a satisfactory result obtained.