Ultrasonic Surface Rolling Process Research Articles

Reconstruction Mechanism of Surface Integrity for Laser Additive Manufactured 316 L Stainless Steel Subjected to Ultrasonic Surface Rolling Process: Numerical Simulation and Experimental Verification

Reconstruction Mechanism of Surface Integrity for Laser Additive Manufactured 316 L Stainless Steel Subjected to Ultrasonic Surface Rolling Process: Numerical Simulation and Experimental Verification

Surface Properties and Fatigue Behavior of 6061 Aluminum Alloy by Multi-pass Ultrasonic Surface Rolling Process

Surface Properties and Fatigue Behavior of 6061 Aluminum Alloy by Multi-pass Ultrasonic Surface Rolling Process

Evolution of microstructure and mechanical properties of aluminum alloy induced by turning and ultrasonic surface rolling process

The microstructure and mechanical properties have a significant impact on the service performance of materials. This paper compared the microstructure and mechanical properties of 2024 aluminum alloy subjected to turning and ultrasonic surface rolling process (USRP). It was found that both turning and USRP can cause grain refinement and increased microhardness. The grain refinement induced by USRP was attributed to dislocation proliferation and T-phase fragmentation; At the same time, a quantitative relationship model between microhardness and microstructure during turning and USRP was constructed. The results showed that precipitation had the greatest impact on the microhardness induced by turning, while dislocations and grain refinement had the greatest impact on the microhardness induced by USRP; In addition, the mechanical performance response mechanism of the materials after turning and USRP was elucidated, and it was found that USRP can significantly enhance the yield strength of the materials.

Formation mechanism of surface gradient microstructure and mechanical properties evolution of Mg–Y-Nd-Gd-Zr alloy by ultrasonic rolling

The evolution mechanism of the microstructure and mechanical properties of a Mg–Y-Nd-Gd-Zr alloy subjected to different numbers of passes of the ultrasonic surface rolling process (USRP) was investigated. The results demonstrated an initial decrease followed by an increase in the surface roughness of the alloy. The optimal surface roughness was achieved after four passes, with a contour mean deviation of 0.06 μm and micro-roughness 10-point height of 0.55 μm. After the USRP, the alloy exhibited a composite gradient structure characterized by increased grain size and decreased dislocation, lamination, and twin densities. The depth of the gradient layer increased with each additional USRP pass, ranging from 650 μm (1 pass) to 910 μm (8 passes). Furthermore, the USRP treatment effectively enhanced the alloy strength; compared with the untreated samples; the yield strength increased by 34.2% in the gradient sample after one pass. No significant change was observed in the YS with an increasing number of rolling passes for Mg alloys, whereas both the tensile strength and elongation showed improvements. High-density twinning played a crucial role in enhancing the YS of the gradient samples without significant variation across different numbers of rolling passes, thus following a consistent pattern. The formation of more nanocrystals on the surface of Mg alloys after multiple rolling cycles is key to preventing premature fracture failure and improving the work-hardening rate.

Experimental study on surface roughness processed by ultrasonic surface rolling process

In order to explore the formation principle of microscopic morphology of the lower surface of USRP, USRP theoretical analysis and processing experiments are carried out. Firstly, the spatial motion trajectory of tool head by USRP is established to reveal formation principle of surface morphology. Additionally, this experiment employs a single-factor experimental design method. The influence law of process parameters and surface roughness is obtained. The results show that the workpiece speed affects the circumferential machining density of the part, and the feed speed affects the axial density of the part. Surface roughness initially decreases and subsequently increases with rising amplitudes and static pressure. It gradually rises with improvement of feed rate and rotational speed. This provides a new way to adjust the surface topography of USRP in the future.

Surface integrity and rolling contact fatigue behavior of 18CrNiMo7-6 steel subjected to ultrasonic surface rolling process

In this study, the effect of ultrasonic surface rolling process (USRP) on the surface integrity and rolling contact fatigue (RCF) behavior of 18CrNiMo7-6 steel have been conducted. The different static loads and ultrasonic amplitudes on surface morphology, surface roughness, microstructure, microhardness, and residual stress were examined. Results revealed that USRP treatment resulted in a remarkably smooth surface with the surface roughness value Ra of 0.035 μm. Moreover, USRP treatment induced the formation of nanocrystalline and ultrafine crystalline structures on the surface layer. Additionally, the sample surface was subjected to a significant layer of residual compressive stress, reaching a maximum value of approximately −1243 MPa and extending to a depth of around 1500 μm. The surface microhardness had been increased to 808 HV0.2. The comprehensive integration of grain refinement, the increase of surface microhardness, and the induction of residual compressive stress led to an improvement in RCF life.

Electrochemical corrosion behavior of 7075 aluminum alloy with different ultrasonic surface rolling microstructures

7075 Al alloy is strengthened by ultrasonic surface rolling process (USRP), and the process parameters are changed to regulate the microstructure. The thickness, grain size and distribution of different strengthening layer are characterized in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The influence of different strengthening structures on their electrochemical corrosion behavior are studied using scanning Kelvin probe (SKP) and electrochemical impedance spectroscopy (EIS). The results show that the average grain size of untreated Al alloy is 2.89 μm, the surface SKP potential is low and fluctuates greatly, and has high sensitivity to pitting corrosion. After USRP treatment, the surface roughness of 7075 Al alloy decreases, the grain size is significantly refined and shows a gradient distribution, SKP potential in the strengthening area increases and becomes more stable, the passive film on the surface thickens, the density of pits significantly decreases, and the corrosion resistance is improved. Besides, the samples with thicker plastic deformation layer and surface nanocrystallization (average size of 39.9 nm) exhibit better performance compared to other samples.

Study on Fretting Wear Properties of GCr15 Steel Via Ultrasonic Surface Rolling Process

Abstract Ultrasonic surface rolling (USR) was applied to GCr15 steel with different static loads and passes to improve the friction and wear properties, and then the fretting wear mechanism of GCr15 steel after USR treatment was systematically investigated. The results showed that the specimens treated by the USR had lower surface roughness and significantly increased compressive residual stress and microhardness. Furthermore, severe plastic deformation occurred in the surface layer of the specimen, which refined the grains and increased the density of high- and low-angle grain boundaries. Besides, the results of the fretting test showed that the USR treated specimens had lower wear volume, dissipated energy, and steady-state friction coefficient. The fretting wear resistance increased with the static load and the number of passes. The fretting wear mechanism changed from abrasive wear and severe adhesive wear to slight fatigue wear and abrasive wear owing to the use of the USR treatment. Surface smoothing and hardening are responsible for the improvement in the fretting wear properties of GCr15 steel for USR treatment.

Effect of ultrasonic surface rolling process on the surface properties of Mg-Gd-Zn-Zr alloy

This article focused on the effect of ultrasonic surface rolling process (USRP) on the surface morphology, microstructure, microhardness and corrosion behavior of Mg-Gd-Zn-Zr alloy. Due to plastic deformation during USRP, the surface integrity of Mg-Gd-Zn-Zr alloy was reconstructed with the decrease of surface roughness, the introduction of grain refinement and twinning. It contributed to improve the microhardness and corrosion behavior that the surface microhardness increased about 25.5 % to 112.47 HV, and the corrosion current density decreased about 99.86 % to 1.362 × 10-4 μA/cm2. The results indicated that the USRP exhibited good application prospects in improving the surface properties of Mg alloys.

Investigating the Dynamic Mechanical Properties and Strengthening Mechanisms of Ti-6Al-4V Alloy by Using the Ultrasonic Surface Rolling Process.

The demand for titanium alloy has been increasing in various industries, including aerospace, marine, and biomedical fields, as they fulfilled the need for lightweight, high-strength, and corrosion-resistant material for modern manufacturing. However, titanium alloy has relatively low hardness, poor wear performance, and fatigue properties, which limits its popularization and application. These disadvantages could be efficiently overcome by surface strengthening technology, such as the ultrasonic surface rolling process (USRP). In this study, the true thermo-mechanical deformation behavior of Ti-6Al-4V was obtained by dynamic mechanical experiment using a Hopkinson pressure bar. Moreover, USRP was applied on the Ti-6Al-4V workpiece with different parameters of static forces to investigate the evolution in surface morphology, surface roughness, microstructure, hardness, residual stress, and fatigue performance. The strain rate and temperature during the USRP of Ti-6Al-4V under the corresponding conditions were about 3000 s-1 and 200 °C, respectively, which were derived from the numerical simulation. The correlation between the true thermo-mechanical behavior of Ti-6Al-4V alloy and the USRP parameters of the Ti-6Al-4V workpiece was established, which could provide a theoretical contribution to the optimization of the USRP parameters. After USRP, the cross-sectional hardness distribution of the workpiece was shown to initially rise, followed by a subsequent decrease, ultimately to matrix hardness. The cross-sectional residual compressive stress distribution of the workpiece showed a tendency to initially reduce, then increase, and finally decrease to zero. The fatigue performance of the workpiece was greatly enhanced after USRP due to the effect of grain refinement, work hardening, and beneficial residual compressive stress, thereby inhibiting the propagation of the fatigue crack. However, it could be noted that the excessive static force parameter of USRP could induce the decline in surface finish and compressive residual stress of the workpiece, which eliminated the beneficial effect of the USRP treatment. This indicated that the choice of the optimal USRP parameters was highly crucial. This work would be conducive to achieving high-efficiency and low-damage USRP machining, which could be used to effectively guide the development of high-end equipment manufacturing.

Effects of Ultrasonic Surface Rolling Processing on the Surface Properties of 4Cr13 Stainless Steel

Effects of Ultrasonic Surface Rolling Processing on the Surface Properties of 4Cr13 Stainless Steel

Effect of ultrasonic surface rolling on the friction and wear properties of 8620H carburized steel at elevated temperatures

The surface strengthening treatment of 8620H carburized steel was carried out by ultrasonic surface rolling (USR) process, and the samples with and without the treatment were subjected to friction and wear experiments at 25°C, 100°C, and 150°C. The experimental results showed that the samples with USR treatment had higher surface hardness, lower surface roughness, deeper hardened layer depth, and higher surface residual compressive stress than the samples without USR treatment. Meanwhile, the wear degree of the samples deteriorated as the temperature increased, but the anti-wear performance of the samples with USR treatment increased by 52.9%, 29.8%, and 14.9% compared with the samples without USR treatment at 25°C, 100°C, and 150°C, respectively, indicating that the USR treatment still had a better strengthening effect at high temperatures.

Effect of high-frequency dynamic characteristics in the ultrasonic surface rolling process on the surface properties

Ultrasonic surface rolling process (USRP) is a combination of ultrasonic impact and deep rolling techniques. However, the addition of ultrasonic vibrations complicates the working mechanism of USRP tools. Existing studies rarely consider the evolution of dynamic characteristics in USRP tools resulting from changes in ultrasonic amplitudes, which undoubtedly exert a significant influence on surface properties. Moreover, they typically limit the ultrasonic amplitude to a small range. This study aims to identify the boundary process parameters to differentiate between stable and unstable dynamic characteristics during USRP and to compare their effects on the surface integrity and the plastic deformation. Therefore, an equivalent USRP tool model was proposed to analyse the working mechanism at a large-scale ultrasonic amplitude. The boundary USRP parameters responsible for different dynamic characteristics were experimentally explored. Finally, comparative USRP experiments on the Ti-6Al-4 V alloy were conducted, and it was observed that USRP parameters under stable dynamic characteristics were beneficial to the excellent surface roughness. Conversely, altering the ultrasonic amplitude to attain unstable dynamic characteristics leads to a notable degradation in the surface quality; however, the extent of plastic deformation is significantly increased. This study provides insights into the effects of dynamic characteristics in USRP, thereby contributing to a deeper understanding of the process and facilitating effective design of process parameters.

Surface modification and its effect on fatigue performance of nickel-based superalloy treated by ultrasonic surface rolling process

In the process of material removal, the metallurgical and mechanical properties of the surface layer of GH4169 superalloy have changed significantly, which has an adverse effect on the fatigue life. Therefore, surface strengthening process is indispensable as the last process of part manufacturing. In the paper, once and four times of ultrasonic surface rolling process (USRP) are carried out on GH4169 superalloy. The results show that USRP treatment improves the degree of grain refinement, the proportion of low angle grain boundaries (LAGBs) and dislocation density of the surface layer. The USRP treatment with four times forms a preferred orientation (〈101〉//TD) on the surface layer, and, the grain refinement mechanism is revealed. Moreover, USRP treatment changes the crack propagation mode from transgranular to intergranular. The fatigue tests indicate that the fatigue life of samples treated with USRP with once and USRP with four times increase by 55.6% and 138.6%, respectively. It can be inferred that the surface topography, residual stress, microstructure and degree of working hardening are the main factors affecting the low cycle fatigue properties of USRP treated samples.

Further enhancement of surface mechanical properties of carburized 9310 steel by electropulsing-assisted ultrasonic surface rolling process

9310 carburized steel experiences significant wear and spalling problems when operating under high friction and heavy loads, which severely restricts its applications in the aviation industry. Therefore, it holds great significance to further enhance the surface mechanical properties of 9310 carburized steel through suitable surface strengthening technologies. The Electropulsing-Assisted Ultrasonic Surface Rolling Process (EP-USRP) has been successfully applied to carburized 9310 steel, yielding significant improvements in surface quality, hardness, friction and wear properties, and microstructure. Systematic investigations were conducted under varying EP-USRP parameters. Regarding the electric pulse parameters, it is observed that with the increase in output voltage, surface properties such as surface roughness and surface hardness tend to first optimize and then deteriorate. After applying EP-USRP with optimal parameters, the surface roughness of carburized 9310 steel was reduced to Ra 0.154 μm, a mere 5 % of its initial value. The surface hardness experienced a substantial increase, reaching 909.2 HV, representing a notable improvement of 29.9 % compared to the original sample, with a corresponding hardening depth of 1400 μm. Moreover, the wear amount of carburized 9310 steel witnessed a remarkable reduction to 11.8 % of its initial value, accompanied by a decrease in the coefficient of friction to 43.0 %. The enhancement of carburized 9310 steel through EP-USRP is attributed to two key mechanisms: deformation hardening induced by severe plastic deformation and microstructure strengthening resulting from strain-induced martensitic transformation. Among them, the severe plastic deformation mechanism is dominant, Through these mechanisms, the proportion of small-angle boundaries in carburized 9310 steel strengthened by EP-USRP increased. Additionally, the grain size of the surface layer decreased, and the content of retained austenite in the surface layer decreased, collectively contributing to significant improvements in surface properties, as well as friction and wear performance.

Influence of ultrasonic surface rolling on tensile properties of high carbon low alloy quenching-partitioning-tempering steel

The effect of ultrasonic surface rolling process on tensile properties of a novel Fe-0.6C-2.0Al-1.5Mn-0.04 Nb quenching-partitioning-tempering steel was investigated. Optical microscope, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy were brought out to characterize the microstructure. Compared with quenching-partitioning-tempering steel, the strength and plasticity of the ultrasonic rolling specimen were increased simultaneously, reaching 1329.1 MPa and 23.6%, respectively, and the product of strength and elongation reached the range of the third generation Advanced High Strength Steels. The plasticity improvement mechanism of the USRP1specimen is mainly stemmed from two aspects: First, obvious strain gradients during the tensile process was found in the USRP specimens, which not only avoids the strain localization, but also generates a biaxial stress state. The geometrically necessary dislocations induced by the strain gradient and the dislocations induced by the biaxial stress state promoted extra work hardening, thus ensuring high plasticity of the material. Second, there was a moderate content and small size of twinned martensite in the USRP1 specimen. The improvement in yield strength of the USRP specimens primarily results from grain refinement strengthening, dislocation strengthening, phase transformation strengthening, and back stress strengthening. Among them, phase transformation strengthening contributed the most.

Effect of laser shock peening on fretting wear behaviour of AISI 304 stainless alloy

Unlike many other surface treatment techniques, such as shot peening (SP), low plasticity burnishing (LPB), ultrasonic surface rolling process (USRP), ultrasonic nanocrystal surface modification (UNSM), laser shock peening (LSP) is a non-contact process. This means that LSP achieves surface modification without direct physical contact, thereby eliminating the risk of media contamination and undesired wear on the peening equipment. As a surface hardening technology, LSP tends to produce a hardened layer with a high gradient of residual stress (RS) in the near-surface, significantly enhancing wear resistance. The well-known wear theories applied for numerical prediction, whether Archard model or dissipated frictional-energy model, contain a multiplier for contact pressure and relative slip amplitude p·ds or shear stress and relative slip amplitude q·ds, respectively. These multipliers are sensitive to the mechanical properties near the surface. Additionally, the wear profile is governed not only by the wear effect but also by the deformation of materials. Therefore, to accurately evaluate the wear performance for surface-hardened materials, the influence of RS is hard to be overlooked. In this work, the finite element method (FEM) is utilised to construct a 3D numerical model, which ignores and considers RS, for both as-received and LSP-treated samples. Two distinct RS distributions induced by different scanning strategies (one- and five-time), are introduced in the finite element (FE) model. The numerical simulation results are then compared with the experimental data to verify the accuracy of the fretting wear model built in this study. On this basis, the impact of different RS distributions on fretting wear characteristics, including wear profile and volume, is extensively investigated. The findings reveal that higher amplitude RS can reduce the degree of fretting wear to a greater extent, highlighting the beneficial role of RS in enhancing wear resistance. Furthermore, the numerical models incorporating RS demonstrate superior predictive accuracy compared to those that omit RS. This naturally underscores the importance of integrating RS in numerical simulations of LSP and other surface-hardened materials.

Synergistic effects of heat-assisted ultrasonic rolling textures and self-lubricating coatings on the friction and wear properties of AISI 52100 steel

Wear is an important factor in limiting the service life of AISI 52100 steel components. In order to improve the tribological properties of AISI 52100 steel, we investigated the synergy between polyphenylene sulfide-silicon dioxide/polytetrafluoroethylene (PPS-SiO2/PTFE) self-lubricating coatings and surface textures fabricated by heat-assisted ultrasonic surface rolling process (USRP). The influences of different heat-assisted temperatures (20, 80, 140, and 200 ℃) on the surface characteristics of the textures such as morphology, hardness, and residual stress were investigated. The synergistic effects of self-lubricating coatings and textures at different heat-assisted temperatures were investigated by dry friction and wear tests. The results showed that the synergistic effect of the coating with the texture at 200 °C had a performance improvement than the individual effect, but the synergistic effects with textures at other heat-assisted temperatures had a negative influence. The heat-assisted temperature influenced the synergistic effect by affecting the texture shape and strengthening effect, and the influence of texture shape was stronger. The texture with an appropriate shape not only had a strengthening effect to increase the load-bearing capacity of the coating-substrate system, but also stored the coating material to improve the wear resistance.

Improving the fatigue resistance of plasma electrolytic oxidation coated titanium alloy by ultrasonic surface rolling pretreatment

Plasma electrolytic oxidation (PEO) damages fatigue strength of titanium alloy, ultrasonic surface rolling process (USRP) pretreatment is used to mitigate this adverse effect. The microstructure, stress distribution and fatigue performance of Ti6Al4V alloy with different treatment are tested by FESEM, TEM, X-ray stress tester and rotating-bending fatigue tests, and anti-fatigue mechanism of co-strengthened sample is discussed. USRP treatment refines surface grains and introduces a compressive stress field of above 560 μm, which helps to improve the compactness and reduce surface roughness of PEO coating, and significantly increase fatigue resistance of PEO coated samples. Under covering the coating of 20 μm, the fatigue life of co-strengthened sample is about 14 times higher than that of simple PEO sample at 600 MPa, and fatigue crack source also changes from multi-source to single-source and transfers to the subsurface. PEO consumes part of surface nanocrystalline layer and releases some compressive stress for ultrasonic-rolled sample, but the effective compressive stress field with a thickness of 180 μm is still present, and the grains at coating/substrate interface also remain at the nanoscale (∼81 nm), which are the key reasons for USRP to improve fatigue resistance of titanium alloy treated by PEO.

Effect of contact stress and slip amplitude on fretting fatigue behaviour of ultrasonic surface nanocrystallized TC11 titanium alloy

In this paper, combined experimental and numerical methods are applied to investigate the effect of different contact stress and slip amplitude on the fretting fatigue (FF) behaviour of TC11 titanium alloy with gradient nanostructure introduced by ultrasonic surface rolling process (USRP). The properties of gradient nanostructure are characterized using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray residual stress tester, microhardness tester. As evidenced by the FF experimental results, USRP can significantly improve the FF life of TC11 by introducing large compressive residual stress and work hardening layer. The dominant parameters in improving the FF resistance under different loading conditions are investigated. In addition, the simulated results from Abaqus show that contact stress plays a more important role in influencing FF life compared to fretting bridge span, which is attributed to the change in slip amplitude and stress concentration. Fretting fatigue life initially increases and then decreases with contact stress and there is a contact stress threshold that leads to minimum lifetime. This threshold of USRP specimens is greater than that of untreated specimens. The transition of fretting mode along with contact stress is observed and discussed.