Abrasive Wear Resistance of Plasma-Nitrided Ti Enhanced by Ultrasonic Surface Rolling Processing Pre-Treatment

Frictional Wear and Thermal Fatigue Properties of Die Steel after Ultrasound-Assisted Alloying

The surface layer of 8407 die steel was strengthened using the combination of ultrasonic surface rolling and high-energy ion implanting in the present work. The strengthened layer was then characterized via microstructure observation, composition analysis, and hardness test. After that, the frictional wear and thermal fatigue properties of high-energy ion implanting specimens and composite-reinforced specimens were compared. Results show that the pretreatment of specimens with ultrasonic surface rolling causes grain refinement in the material surface, which promotes the strengthening effect of high-energy ion implanting. The wear volume of composite-reinforced specimens at medium and high frequencies is reduced by about 20%, and the wear resistance of these specimens is significantly improved with a lower friction coefficient and wear volume at moderate and high frequencies in alternating load friction experiments. Meanwhile, the thermal fatigue crack depth of composite-reinforced specimens is reduced by about 47.5%, which effectively prevents the growth of thermal cracks in the surface, thus improving the curing ability of the implanted elements. Therefore, composite strengthening of the mold steel surface is conducive to improving the cycle life, ensuring accuracy, effectively hindering the expansion of thermal cracks, and saving the cost of production.

Ultrasonic Surface Rolling Process: Properties, Characterization, and Applications

Ultrasonic surface rolling process (USRP) is a novel surface severe plastic deformation (SPD) method that integrates ultrasonic impact peening (UIP) and deep rolling (DR) to enhance the surface integrity and surface mechanical properties of engineering materials. USRP can induce gradient nanostructured surface (GNS) layers on the substrate, providing superior mechanical properties, thus preventing premature material failure. Herein, a comprehensive overview of current-state-of-the art USRP is provided. More specifically, the effect of the USRP on a broad range of materials exclusively used for aerospace, automotive, nuclear, and chemical industries is explained. Furthermore, the effect of USRP on different mechanical properties, such as hardness, tensile, fatigue, wear resistance, residual stress, corrosion resistance, and surface roughness are summarized. In addition, the effect of USRP on grain refinement and the formation of gradient microstructure is discussed. Finally, this study elucidates the application and recent advances of the USRP process.