Influence of Microstructure on Impact Toughness and Pitting Sensitivity of 17-4PH Martensitic Stainless Steel

Three kinds of heat treatments were performed on 17-4PH martensitic stainless steel: solution (sample No. 1), quenched and tempered + solution (sample No. 2), solution + quenched and tempered + aging (samples No. 3 and No. 4) ,and 17-4PH martensitic stainless steel with different microstructures was obtained. Impact test, morphology observation, electrochemical performance test, and immersion test were used to study the influence of microstructure on the impact toughness at 0 ℃ and pitting sensitivity of 17-4PH martensitic stainless steel. The results show that the impact toughness of the solid solution + quenched and tempered + aging treatment sample was the highest, followed by the solid solution + quenched and tempered sample, and the solution treated sample had the lowest impact toughness. During the aging process, temperature and aging were the main factors affecting impact toughness. The corrosion potential E_corr of No. 1 sample was the lowest. After quenching and tempering + aging, the E_corr of the sample was greatly improved. The pitting potential of several samples was No. 2 > No. 4 > No. 3 > No. 1 from high to low, and the corrosion rate was No. 1 > No. 3 > No. 4 > No. 2.