Method for displaying original austenite grain boundary of 40Cr15Mo2VN bearing steel

The invention belongs to the technical field of bearing metallographic detection and provides a method for displaying original austenite grain boundary of 40Cr15Mo2VN bearing steel. The method comprises the following process flows: sampling, quenching, backfiring, preparing samples and corroding, wherein the sample corrosion step comprises the processes of component proportioning of corrosive, configuration of corrosive and metallographic corrosion; the components and the component proportioning of the corrosive is as follows: 2g of potassium permanganate, 4ml of sulphuric acid with the concentration of 98% and 96ml of distilled water; the ground sample with the required grain fineness is arranged in the corrosive solution heated to the temperature of 60-70 DEG C with the grinding surface facing upwards and is thermally corroded for 10-15 minutes. By adopting the method, the sample has clear and complete grain boundary and achieves the grading requirement of manpower and metallographic analysis software.