Corrosive agent for treating grain boundary of 4Cr14Ni14W2Mo heat-resistant steel and application of corrosive agent

The invention discloses a corrosive agent for treating grain boundaries of 4Cr14Ni14W2Mo heat-resistant steel and application of the corrosive agent. The corrosive agent comprises the following components: picric acid, a hydrochloric acid solution and distilled water, wherein the mass volume ratio of the picric acid to the hydrochloric acid solution to the distilled water is (0.5-1) g: (2-10) ml: 100 ml. The application method comprises the following steps: pretreating annealed 4Cr14Ni14W2Mo heat-resistant steel, putting into the corrosive agent, corroding for a certain time, taking out, washing with running water, cleaning with alcohol, drying, observing with 200 times under a microscope to obtain a crystal grain display picture, and judging crystal grains. The annealed 4Cr14Ni14W2Mo heat-resistant steel obtained through the corrosion method is obvious in grain boundary and completely not affected by the structure, all grains can be clearly observed, and high accuracy and precision are achieved. The corrosio