Submerged deflecting abrasive waterjet peening for improving the surface integrity and solid particle erosion resistance of Ti-6Al-4V alloy

Abstract

Waterjet peening is a promising new surface treatment technology, which is increasingly used to improve a metal's surface integrity and mechanical properties. In this study, the surface integrity and solid particle erosion (SPE) resistance of Ti-6Al-4V alloy treated with submerged deflecting abrasive waterjet peening (SDA-WJP) at different standoff distances (D = 3, 6, and 9 mm) were investigated. First, the surface integrity of specimens before and after SDA-WJP treatment was compared, including microstructure, surface roughness, micromorphology, microhardness, and compressive residual stress (CRS). The test results showed that the SDA-WJP-treated specimens formed refined grain deformation layers of 8–24 μm and minimum roughness of Ra = 0.28 μm and Sa = 0.55 μm. The thicknesses of the refined grain hardening layer and CRS field were 140–180 and 120–200 μm, respectively. Finally, the SPE behavior and mechanism of the samples before and after SDA-WJP treatment were studied in the SPE test. The highest increase in SPE resistance was 51 % under different SDA-WJP processes. The microscopic morphology of the eroded surface was observed by scanning electron microscopy. The shallow embedding depth of the particles on the eroded surface after SDA-WJP treatment led to difficult platelet formation for removal. The introduced refined grain hardening layer and CRS field were critical in preventing micro-crack initiation and propagation. This work optimizes the SDA-WJP process parameters for improving the surface integrity and SPE resistance of Ti-6Al-4V alloy, thus providing a reference for the application of SDA-WJP for the improvement of the SPE resistance of aero-engine blades.