Water Jet Peening Research Articles

Improvement of titanium alloy TA19 fatigue life by submerged abrasive waterjet peening: Correlation of its process parameters with surface integrity and fatigue performance

Submerged abrasive waterjet peening (SAWJP) is an effective anti-fatigue manufacturing technology that is widely used to strengthen aeroengine components. This study investigated the correlation of SAWJP process parameters on surface integrity and fatigue life of titanium alloy TA19. SAWJP with different water pressures and standoff distances (SoDs) was conducted on the TA19 specimens. The surface integrity of the specimens before and after SAWJP with different process parameters was experimentally studied, including microstructure, surface roughness, microhardness, and compressive residual stress (CRS). Finally, fatigue tests of the specimens before and after SAWJP treatment with different process parameters were carried out at room temperature. The results highlighted that the fatigue life of the TA19 specimen can be increased by 5.46, 5.98, and 6.28 times under relatively optimal process parameters, which is mainly due to the improved surface integrity of the specimen after SAWJP treatment. However, the fatigue life of specimens treated with improper process parameters is decreased by 0.55 to 0.69 times owing to the terrible surface roughness caused by the material erosion. This work verifies that SAWJP can effectively improve the surface integrity and fatigue life of workpieces, and reveals the relationship between process parameters, surface integrity, and fatigue life, which provides support for the promotion of SAWJP in the manufacturing fields.

Effect of abrasive water jet peening on NaCl-induced hot corrosion behavior of Ti–6Al–4V

Hot corrosion studies were performed on pristine and abrasive water jet peened (AWJP) Ti–6Al–4V surfaces. Oxide scales form on the peened and pristine surfaces when coated with NaCl and exposed to 600 °C for 100 h. Despite similar oxide compositions on both surfaces, the thickness and roughness of the oxide scale on the AWJ peened surface is lower. The hot corrosion rate of the pristine surface is 2.5 times higher than that on the AWJ peened surface. Enhanced hot corrosion resistance of the latter is attributed to compressive residual stresses on the surface that retards diffusion of chloride in the material.

Effect of Laser Peening on the Corrosion Properties of 304L Stainless Steel.

Dry canisters used in nuclear power plants can be subject to localized corrosion, including stress corrosion cracking. External and residual tensile stress can facilitate the occurrence of stress corrosion cracking. Residual stress can arise from welding and plastic deformation. Mitigation methods of residual stress depend upon the energy used and include laser peening, ultrasonic peening, ultrasonic nanocrystal surface modification, shot peening, or water jet peening. Among these, laser peening technology irradiates a continuous laser beam on the surface of metals and alloys at short intervals to add compressive residual stress as a shock wave is caused. This research studied the effect of laser peening with/without a thin aluminum layer on the corrosion properties of welded 304L stainless steel. The intergranular corrosion rate of the laser-peened specimen was a little faster than the rate of the non-peened specimen. However, laser peening enhanced the polarization properties of the cross-section of 304L stainless steel, while the properties of the surface were reduced by laser peening. This behavior was discussed on the basis of the microstructure and residual stress.

Experimental investigation into the effect of process parameters on the Inconel 718 surface integrity for abrasive waterjet peening

Abrasive waterjet peening (AWJP) has been used to modify the mechanical properties of components by introducing plastic deformation and compressive residual stress (CRS) into the workpiece surface. The present study aims to investigate the influence of different AWJP parameters on the surface integrity of Inconel 718 alloy. The AWJP with different pump pressures, standoff distances, traverse speeds, and abrasive flowrates are conducted on the Inconel 718 workpiece. The surface integrity response including surface topography, CRS, hardness, and microstructure of AWJP are investigated, and different AWJP parameters effect on changing trend of surface integrity response is discussed. Results show that the AWJP-treated workpiece with different parameters formed a footprint width of 3.0–4.3 mm, the key factor effect on footprint width is standoff distance. The maximum surface roughness of Sa = 9.06 μm occurs at pump pressure 300 MPa, and pump pressure is more sensitive than other AWJP parameters' effect on surface fluctuation and surface roughness. The thickness of the stress layer is approximately 100–180 μm, and the maximum CRS is larger than 1100 MPa. Pump pressure and standoff distance are two main factors that effect on CRS, while the changing rate effect on CRS is gradually slow with the increase of pump pressure and the reduction of standoff distance. The maximum hardness increases more than 20 % from 490 to 590 HV at a pump pressure of 300 MPa. The pump pressure is the key factor influencing on micro-hardness. The microstructure evolution on the sub-surface of AWJP treated workpiece was characterized by SEM and EBSD, which showed that grains refine and strengthening layer formed on the top surface of the AWJP-treated workpiece surface, also the cracks at pump pressure 300 MPa. The results revealed that AWJP has great development potential in Inconel 718 surface treatment, and pump pressure is the key factor that effect on surface integrity.

Surface strengthening in confined spaces: A novel deflecting abrasive waterjet peening for improving the surface integrity of nickel-based superalloys GH4169

Abrasive waterjet peening (AWJP) has become an essential surface treatment technique to improve the surface integrity and mechanical properties of metallic parts due to its high controllability and small thermal influence. However, since existing AWJP processes are based on straight nozzles, they are difficult for complex geometrical profiles and confined spaces treatment, such as dovetail slots. In the present work, a novel deflecting AWJP (DAWJP) process with a designed deflecting nozzle was proposed and verified by experiments on the nickel-based superalloy GH4169. First, the DAWJP's deflecting nozzle was designed based on the AWJP's straight nozzle and deflecting pin with deflection angle. Second, the internal and external flow field distribution and abrasive movement state of deflecting nozzles with different deflection angles (R = 0, 1, 1.5, 2 mm) were studied by using the FLUENT CFD software. Finally, the surface integrity of the GH4169 specimen treated by the proposed DAWJP with an optimized deflecting nozzle was investigated, including microstructure, height difference, surface roughness and microscopic morphology, surface and subsurface microhardness and compressive residual stress (CRS). The results of this study highlighted that the deflecting nozzle with a deflection angle of 1.5 mm could obtain relatively optimized jet flow velocities of the water and abrasive mixed phases. The GH4169 specimen treated by the DAWJP with different processing parameters using the optimized deflection angle formed a plastic deformation depth of 22–51 μm, a height difference between the as-received and DAWJP treated surface of 4–48 μm, and the surface roughness Ra and Sa of 0.199–0.503 μm and 0.535–0.953 μm. The surface microhardness and CRS of the DAWJP treated specimen were approximately 522–573 HV and 773–991 MPa, which is 7.6 %–18.1 % and 209 %–296 % times higher than the as-received specimen, respectively. The work-hardened layer and CRS depth of the near surface of the specimen induced by the DAWJP treatment were approximately 120–180 μm and 112–203 μm. This work presents a novel DAWJP method and investigates its effect on the surface integrity of the GH4169 material, which is expected to have applications in improving the surface integrity and mechanical properties of metallic parts with confined spaces.

Numerical investigation on the residual stress in abrasive waterjet peening

Numerical investigation on the residual stress in abrasive waterjet peening

Performance Analysis of 7075 Aluminum Alloy Strengthened by Cavitation Water Jet Peening at Different Scanning Speeds

Shot peening technologies can improve the performance of materials and extend the service life of parts. Cavitation water jet peening (CWJP) is a new shot peening technology that uses the shear effect of a high-speed jet in a submerged environment to produce a cluster of bubbles, thereby achieving a significant increase in impact performance. In this paper, CWJP was used to strengthen the surface of the 7075 aluminum alloy (Al7075), and the effects of CWJP with different scanning speeds on its microstructure and mechanical properties were investigated. The morphology evolution revealed that the plastic deformation of the sample surface became more serious and the surface roughness increased with the decrease in scanning speed. The distribution of residual stress and microhardness along the depth direction of the Al7075 was measured before and after the CWJP impact, and it was found that CWJP causes work hardening on the surface of the Al7075 and can convert the subsurface tensile stress of the Al7075 into compressive stress. The mechanism of grain refinement of the Al7075 during plastic deformation was systematically revealed. Therefore, CWJP can effectively improve the surface properties of the 7075 aluminum alloy.

Investigation on surface integrity and fatigue performance in abrasive waterjet peening

Investigation on surface integrity and fatigue performance in abrasive waterjet peening

The impact of sintered density upon the microstructural and residual stress development in an ultrasonic pulsed waterjet peened Al-alloy/AlN composite

A powder metallurgy processed, aluminum-based metal matrix composite (Al-MMC) was sintered to either 95.4 % or 98.8 % of theoretical density, and subsequently surface treated via ultrasonic pulsed waterjet (UPWJ) peening. During peening, the UPWJ traverse speed was varied while the stand-off distance, frequency, and pressure were maintained constant. The microstructures, residual porosity, surface topography, phase composition, and residual stress were subsequently evaluated as a function of the peening condition. The results indicated that the less dense Al-MMC variant was slightly more receptive to plastic deformation at slower traverse speeds. The surface roughness decreased with increasing traverse speed for both sinter conditions. Regardless of the density, the UPWJ peening process was effective in instilling residual compressive stresses on the surface of the Al-MMC, which initially was in residual tension after sintering. The concentration of sub-surface pores was found to be reduced after UPWJ peening for both sintered densities. This phenomenon is linked to the development of residual compressive stresses which penetrated about 380 μm into the UPWJ peened material.

Improving Structure Integrity and Fatigue Properties of 316L Welded Joint by Water Jet Peening Treatment

Improving Structure Integrity and Fatigue Properties of 316L Welded Joint by Water Jet Peening Treatment

Surface characteristics and residual stress generation in Ti-6Al-4 V following ultrasonic pulsed water jet peening

The objective of this study is to examine the influence of ultrasonic pulsed water jet (UPWJ) peening upon Ti-6Al-4 V (Grade 5), through evaluation of the microstructure, surface roughness, and residual stress development. The UPWJ peening treatment was conducted by varying the traverse speed, from 200 to 1000 mm/s, at a constant jet pressure of 69 MPa, frequency of 20 kHz, and stand-off distance of 25.4 mm. The average values of Ra, Rz, and Rsm roughness were recorded using laser confocal microscopy at each traverse speed. The residual stress distribution was analysed through sequential electropolishing of the unpeened and peened surfaces, followed by X-ray diffraction measurements. UPWJ peening resulted in only minor changes to the surface roughness when peening with traverse speeds in a range of 600 to 1000 mm/s. Surface residual compressive stresses for the peened Ti-6Al-4 V samples ranged between −628 ≤ σ ≤ −151 MPa, with the highest value obtained at a traverse speed of 800 mm/s. In-depth residual compressive stress of the treated region was also observed, up to a maximum depth of ~250–300 μm for traverse speeds between 400 and 1000 mm/s. Based on this study, the UPWJ method of surface treatment, where the efficiency of the water jet is enhanced through ultrasonic pulsing, has significant potential for the ‘green’ treatment aerospace and automotive engineering components.

A critical comparative review of cavitation peening and other surface peening methods

Mechanical surface modification such as shot peening offer powerful enhancement of fatigue properties of metals and other materials. Cavitation usually causes surface damage in hydraulic machineries. However, careful selection of process parameters allowed developing an approach known as “cavitation peening.” Its advantage is surface roughness increase is lower than in conventional shot peening as there are no solid collisions involved. As cavitation is a hydrodynamic phenomenon, an understanding of both fluid dynamics and materials science is required. Cavitation peening is distinguished from “water jet peening,” in which water column impulse is used. Another flavor is “Submerged laser peening” that involves the use of a pulsed laser and can be considered a type of cavitation peening where cavitating bubbles are generated due to laser ablation. Ultrasound vibration, a popular method for generating cavitation for cleaning, has also been adapted for cavitation peening. The present comparative review presents key insights and achievements and addresses future directions that are required for advancing cavitation peening technology by considering the mechanisms of cavitation peening based on the reported data for water jet, pulsed laser, and ultrasonic cavitation peening. The data and methods are critically considered and summarized in comparison with shot peening. Strategic view of future challenges is presented. • Fatigue resistance enhancement using water jet, pulsed laser and ultrasonic cavitation peening was quantified • Cavitation peening using jet, pulsed laser & ultrasonic enhanced fatigue properties • Cavitation peening clearly distinguished from water jet peening • Cavitation peening benefits shown to exceed those by shot peening • Dislocation density induced by cavitation peening was lower than by shot peening • Importance of vortex cavitation is shown for experimental and numerical future work

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

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.

Study on the process of abrasive water jet peening for 316L stainless steel

Study on the process of abrasive water jet peening for 316L stainless steel

Reducing Full-Field Residual Stress of Girth Weld With Thick Wall by Combining Local PWHT and Water Jet Peening

Abstract In this paper, a new controlling method combined local postweld heat treatment (PWHT) and water jet peening (WJP) was proposed to reduce full-field residual stress of girth weld with thick wall. The finite element analysis with sequential coupling method and experiment measurement were performed to study the residual stresses distribution before and after the new controlling method. The results show that the hoop and axial stresses through the thickness are all decreased greatly by using the new controlling method. As long as the new controlling method is used with appropriate parameters, the residual stresses on inner surface can be reduced from tensile stresses to compressive stresses, which greatly improve the resistance ability to stress corrosion of inner surface.

Cavitation abrasive integrated waterjet peening process and the effect of process parameters on the surface integrity of TA19 titanium alloy

Waterjet peening has emerged as a potential surface treatment technology, which is gradually being used to improve the surface integrity and mechanical behavior of metal materials. Submerged abrasive waterjet peening, which combines cavitation peening and abrasive waterjet peening and called cavitation abrasive integrated waterjet peening (CAI-WJP), is proposed in this paper and was studied experimentally. The principle of CAI-WJP is first introduced. The effect of the CAI-WJP parameters (i.e., water pressure, standoff distance, traverse speed, path interval, and peening angle) on the surface integrity of TA19 titanium alloy was systematically investigated. Results show that the specimen treated with CAI-WJP using different process parameters formed a plastic deformation layer with a depth of 5–45 μm. The minimum surface roughness of Ra obtained by CAI-WJP was 0.348 μm, which is 28.5% lower than the as-received surface. The maximum surface microhardness increased by up to 21.1%, with a maximum work hardening depth of 150 μm. The surface compressive residual stress (CRS) increased to approximately 640–800 MPa compared with the original CRS of 50–80 MPa on the as-received specimen, and a maximum CRS depth of 360 μm was obtained. The microstructure evolution on the topmost surface and subsurface of the specimen treated with CAI-WJP with a water pressure of 100 MPa was observed by transmission electron microscopy, which showed that nanocrystallization with amorphization occurred, and nanocrystals with an average size of 6.9 nm formed on the topmost surface. In addition, many dislocation cells and tangles formed on the subsurface with a depth of 15 μm, and a number of dislocation loops, walls, and pinning were found at the depth of 150 μm. This work verifies the effectiveness of the proposed CAI-WJP and provides a favorable reference for how to pick up optimized CAI-WJP process parameters.

Effect of Nozzle Outlet Type on the Flow Field Velocity and Impact Pressure of High-Pressure Water Jet Peening

Abstract Water jet peening can effectively improve the fatigue strength of metal materials, and the outlet shape of nozzle greatly affects the effect of water jet peening. In this paper, the effects of nozzle outlet shape on water jet velocity and impact pressure are studied by numerical simulation, and the jet velocity and dynamic pressure for different standoff distances are also discussed. The results show that the water jets of square, circular, and triangular nozzles are highly concentrated, and the water jet of elliptical nozzles is the most divergent. The axial velocity attenuation of the square nozzle along the axis is slower than that of the other three nozzles. The water axial velocity of the elliptical nozzle attenuates fastest, and the length of the core segment of the water jet is the smallest. Within a certain axial distance, the dynamic pressure area in the central area of the elliptical water jet is obviously larger than that of the other three nozzles, and the effective treatment range is large, which is more suitable for the welding surface strengthening operation.

Modelling and experimental study of surface treatment in abrasive waterjet peening of Nickel-based superalloy: Inverse problem

Abrasive waterjet peening (AWJP) is a promising method of surface treatment for modifying mechanical properties of components by introducing compressive residual stress (CRS) to a workpiece surface. Many efforts have been paid so far to modelling and optimisation of the AWJP process, however, most of these studies focus on the forward problems, i.e. estimating the CRS of workpiece surface according to processing parameters. There are still significant challenges in implanting different CRS at target areas in workpiece surface, which is the foundation of implanting uniform distribution of CRS on free-form surface or workpiece with uneven initial stress state. In this paper, a novel temporally and spatially controlled method for AWJP has been proposed, where the distribution of CRS can be adjusted by the optimisation of the abrasive waterjet parameters. That is, to achieve the AWJP system configuration for specific CRS on a target area, an inverse problem of CRS distribution has been modelled and solved, where the pump pressure, traverse speed and centre distance were optimised together to reach a prescribed CRS distribution. The proposed method was validated through experiments of implanting uniform distribution and non-uniform distribution of CRS at target areas. The results revealed that the maximum error between target and experimental CRS was only 14.25% in 18 sets of experiments. In addition, microstructure analysis of the AWJP surface suggested that a relatively low pump pressure and traverse speed can be selected to induce grain refinement and strain hardening layer on the workpiece surface without cracks and heavy surface topography fluctuations.

A new calculation formula to describe the dynamic pressure of water jet peening with elliptical nozzle for high-efficiency treatment

Water jet peening is a good potential method to control welding residual stresses. The water jet with elliptical nozzle can improve the treatment efficiency due to its large treatment area. In this article, the water jet velocity and dynamic pressure for different elliptical nozzle dimensions and standoff distances are discussed by numerical simulation. The results show that when the axial distance is 10 mm, the effective impact diameter of the elliptical nozzle a/b=8–12 is about 2 times or more than that of the circular nozzle. The length of the jet core of the elliptical nozzle is only related to the outlet structure and is independent of the inlet pressure. The correlation between the dimensionless core length of the elliptical water jet and its long and short axes is derived. When the ratio of the major axis to the minor axis is between 7 and 13, the core length of the elliptical water jet is 7–7.5 times that of its minor axis. Combining the suitable treatment area and dynamic pressure, the elliptical nozzle with an axis ratio of 8 is recommended to control the welding residual stress. Finally, a new formula for calculating dynamic pressure distribution is proposed for the elliptical nozzle water jet at different stages.

Influence of SiC pellets water jet peening on the surface integrity of 7075-T6 aluminum alloy

This work investigates the influences of water jet parameters, including jet pressure, nozzle moving speed, target range, and track interval, on the shot peening of 7075-T6 aluminum alloy. SiC pellets 0.1 mm in diameter are added into the water jet peening (WJP) process. The shot peened workpiece surface is then measured with a roughness tester, a microhardness METER, a METALLURGRAPHIC microscope (MO), and a scanning electron microscope (SEM). The influences of solid pellet WJP on workpiece surface roughness, microhardness, surface residual stress, and surface topography are examined. The results show that jet pressure is positively proportional to surface roughness and microhardness. However as nozzle moving speed and target range increase, the surface roughness and microhardness of the shot peened workpiece begin to decrease. At the track interval of 0.15 mm, the surface roughness of the treated workpiece is a minimum of 0.61 μm. The surface residual stress of the treated workpiece is also notably improved. The residual stress perpendicular to the trajectory is marginally higher than that along the trajectory, but the difference is limited. Further studies reveal that solid pellet WJF treatment of 7075-T6 is the most effective in the jet pressure interval of 25 MPã30 MPa. The optimal nozzle moving speed is 650 mm/miñ750 mm/min. The target range can be selected between 10 and 12.5 mm. The track interval must be greater than 0.1 mm.