The interaction between ε-copper and dislocation in a high copper 17-4PH steel

The interaction between epsilon-copper and dislocation in a high copper 17-4PH stainless steel is investigated as well as the effect of solution temperature, aging temperature and aging time on the microstructure and mechanical properties. Meanwhile, the relationship between precipitates and yield ratio of the steel is also discussed. The conventional tensile test was used to determine the yield strength and ultimate tensile strength. Microstructure of the experimental steel was observed by optical microscope (OM) and transmission electron microscope (TEM). The reversed austenite volume was measured by means of x-ray diffraction (XRD). The results show that the solution strengthening effect improves with the solution temperature in range of 900 degrees C-1060 degrees C. The solution temperature, aging temperature and time have a strong effect on the size and content of precipitate phase. It is strengthened through shearing mechanism and Orowan bypass mechanism for 17-4PH steel at the aging temperature of 480 degrees C while it is dominated by Orowan bypass mechanism at 620 degrees C. The yield ratio of 17-4PH is depended on the microstructure constituents including the type of soft phase and hard phase.