A corrosion method suitable for the microstructure of heat-resistant steel for air valve

The hot rolled and aged 5Cr21Mn9Ni4N heat-resistant steels were corroded by different corrosion agents, and the effects of different corrosion agents on the corrosion results of 5Cr21Mn9Ni4N steel were studied. The results show that the traditional nitric acid ethanol solution could not corrode the sample, and there was no change on the surface of the sample. Ferric chloride hydrochloric acid aquenous solution could not make the sample show clear and complete microstructure and grain boundary, and there was excessive corrosion phenomenon. Using 5 g FeCl₃+50 mL HCl+100 mL H₂O etchant and 10 g CuSO₄+15 mL H₂SO₄+100 mL HCl+5 mL C₃H₈O₃ etchant to corrode the hot rolled and aged 5Cr21Mn9Ni4N steels at room temperature, the austenite structure of the material could be clearly displayed.