Influence of submerged micro-abrasive waterjet peening on surface integrity and fatigue performance of TA19 titanium alloy

Abstract

Waterjet peening has become a critical surface treatment technology due to its great potential for improving the surface integrity and fatigue performance of metallic materials. The present study aims to investigate the influence of submerged micro-abrasive waterjet peening (SMA-WJP) on the surface integrity and fatigue properties of TA19 titanium alloy. First, the SMA-WJP with different water pressure (P = 70, 100, and 130 MPa) was conducted on the TA19 specimen. The surface integrity of the specimen before and after SMA-WJP treatment was studied, including the microstructure, surface roughness, microscopic morphology, microhardness, and residual stress. Results showed that the SMA-WJP treated specimen with different water pressure formed a plastic deformation layer with a depth of 24–44 μm, the minimum surface roughness of Ra = 0.363 μm and Sa = 0.95 μm. The depth of the work-hardened layer and compressive residual stress (CRS) layer was approximately 100–150 μm and 160–290 μm. The microstructure evolution on the top surface and sub-surface of the as-received and SMA-WJP treated specimens were characterized by transmission electron microscopy (TEM), which showed that nanocrystals with an average size of 12 nm and high density of dislocations formed on the top surface of the SMA-WJP treated specimen. Finally, stress-controlled high-cycle fatigue (HCF) tests were carried out to study the fatigue behavior of the TA19 titanium alloy before and after SMA-WJP treatment. The HCF life of the specimen is increased by a maximum of 2.72 times. The fatigue fracture surface was examined with scanning electron microscopy (SEM), which revealed that the existence of the plastic deformation layer and large CRS induced by SMA-WJP could effectively inhibit the initiation and propagation of cracks. This work enriches the waterjet peening process by investigating submerged abrasive waterjet peening and brings a new solution for improving the surface integrity and fatigue performance of TA19 titanium alloy.