Effect of Aging Temperature on Erosion-Corrosion Behavior of 17-4PH Stainless Steels in Dilute Sulphuric Acid Slurry

The effect of aging temperature on erosion-corrosion (E-C) behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on E-C behavior of 17-4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E-C test were observed by using scanning electron microscope (SEM). The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 °C to 610 °C, the hardness reached the highest value near the temperature 460 °C. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows: pure erosion (wear) was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460 °C was the most excellent due to the best precipitation strengthening effect of fine and dispersed ɛ-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials.