Method for displaying original austenite grain boundary of ferrite steel

The invention discloses a display method of a ferrite steel original austenite grain boundary. The display method comprises the steps of sample preparation, sample heating in a protective atmosphere and grain size measurement. According to the method, picric acid is not adopted, analysis means such as a scanning electron microscope and an electron microscope are combined, the reagent obtaining difficulty is lowered, the test method is high in repeatability, and the accuracy and reliability of the test method are improved. The austenite grain size can be detected and analyzed in the heat preservation process, detection and analysis can also be carried out after the test piece is cooled, and the method has the advantage of being convenient to detect. By means of the method, the austenite grain boundary can be clearly displayed when most of ferrite steel is heated to be close to the Ac1 point, so that the austenite grain size is rapidly detected, and a sample in the quenching and tempering stage can be effective