Enhancement of the Fatigue Performance of 17-4PH Stainless Steel Material Extrusion Products by Vibration-Assisted Machining

Metal material extrusion (MME) technique has great application potential in the industrial field. However, the MME-sintered products are prone to failure under fatigue loads due to the defects of internal pores, inclusions, etc., limiting their application in functional and structural components. To effectively improve the fatigue performance of MME products, a vibration-assisted machining (VAM) method was proposed for fabricating MME parts. Based on the inverse piezoelectric effect, a vibrating ME system was constructed, and tensile and fatigue specimens were fabricated through the shaping–debinding–sintering process with different VAM applied. Subsequently, the density, shrinkage, tensile properties, and fatigue properties of the specimens were experimentally investigated. The corresponding damage fatigue life prediction model was then established to reveal the mechanism of VAM influence on their fatigue performance, and it was validated through the comparison between predicted and measured data. It was shown that VAM could effectively improve the fatigue performance of MME products, and their tensile and fatigue properties would be further improved with the increasing vibration frequency or amplitude. Compared with the measured data, the proposed theoretical model was reliable to give accurate predictions in the fatigue life of MME products, with the error between 1.39% and 11.64%.