Ultrasonic Surface Rolling Process Research Articles

Surface fatigue characterization and its enhancement by the engineered ultrasonic rolling process for 300 M ultrahigh strength steel

The fatigue life of surface layer (FSL) is innovatively characterized to accurately capture the effect of surface integrity on the fatigue behavior of the components. The sensitivity of FSL of 300 M ultrahigh strength steel to the surface integrity indexes induced by representative manufacturing processes was analyzed by analytical modeling and fatigue tests from the perspective of engineering fracture mechanics. The ultrasonic surface rolling process (USRP) was introduced to optimize the fatigue limit of 300 M steel, and the improvement in fatigue life was experimentally quantified. Besides, the fracture analysis was conducted to provide the reason why USRP can enhance the fatigue behavior of 300 M steel. The results show that FSL occupies a majority with percentage of over 95 % in the entire fatigue life and a strong relation with the machined surface defects, especially the surface machining marks. The excellent surface finishing effect and high compressive residual stresses induced by engineered USRP could transfer the crack source from surface machining marks into subsurface inclusions, which greatly prolongs the fatigue crack initiation life and thereby the entire fatigue life. To be specific, the fatigue life was elevated by more than 40 times and the fatigue strength was increased by 34.7 % after USRP for the tested 300 M steel.

Quantitative mechanism of abnormal hardening behavior of Ti6Al4V alloy strengthened by ultrasonic surface rolling

In general, the outermost region of a metallic material has the highest hardness after surface mechanical strengthening. However, an abnormal surface hardening behavior was observed in Ti6Al4V alloy after the ultrasonic surface rolling process (USRP) in this work. The region with the highest surface hardening was not at the top surface but at the subsurface. By analyzing the distribution of grain size, dislocation density, texture, and kernel average misorientation (KAM) at different depths from the surface, and combining these findings with finite element analysis (FEA), the microstructural evolution underlying this abnormal surface hardening was elucidated. The microstructural characterization and FEA results indicate that the subsurface region underwent the most significant deformation. Subsequently, through the application of theoretical analysis, the potential mechanism of abnormal hardening of USRP treatment is described quantitatively for the first time. The results demonstrated that the hardening effect resulting from grain refinement was less pronounced, whereas the hardening effect resulting from dislocation pile-up was more prevalent. At the subsurface region of the USRP sample, a large number of interfaces resulted in the highest accumulation of dislocations in this area. Consequently, the subsurface region exhibited the highest microhardness, leading to the abnormal surface hardening phenomenon.

Effect of Ultrasonic Surface Rolling Process by disparate static pressure on a carburized layer of 17CrNiMo6 steel

Effect of Ultrasonic Surface Rolling Process by disparate static pressure on a carburized layer of 17CrNiMo6 steel

Gradient residual stress evolution and its influence on fatigue life under combined carburising heat treatment and ultrasonic surface rolling process

This study combined carburising heat treatment (CHT) with the ultrasonic surface rolling process (USRP) to improve the rotary bending fatigue properties of 18CrNiMo7-6 alloy steel. Based on the experimentally obtained fatigue limit (σ-1), the evolution of gradient compressive residual stress (CRS) of CHT- and CHT + USRP-treated specimens was analysed below the fatigue limit stress level. Subsequently, the evolution mechanism of gradient CRS of the two reinforced specimens was discussed and analysed from the opposing effects of austenite transformation and dislocation density change on the evolution of CRS. The results demonstrated that the selective bending fatigue performance of the alloy was evidently improved after the introduction of CRS; however, the change in fatigue limit was not evident. The durability under other loads (such as cyclic tension/compression and torsion loads) needs further study. The gradient CRS evolution of CHT specimens was mainly caused by the large residual austenite transformation and small dislocation density change. Therefore, the volume expansion caused by residual austenite transformation gradually increased the gradient compression residual stress of CHT specimens with an increased number of cycles. Contrarily, the degree residual stress evolution of CHT + USRP specimens was more affected by the dislocation density, and the gradient compression residual stress gradually decreased with an increased number of cycles. Finally, the residual stress evolution rate of the two reinforced specimens was divided into two stages: fast and slow.

Effects of the Ultrasonic Surface Rolling Process on the Surface Integrity, Wear Resistance, and Corrosion Resistance of 4Cr5MoSiV1 Tool Steel Before and After Quenching

Effects of the Ultrasonic Surface Rolling Process on the Surface Integrity, Wear Resistance, and Corrosion Resistance of 4Cr5MoSiV1 Tool Steel Before and After Quenching

Microstructure evolution and surface strengthening behavior of 300 M ultrahigh strength steel under engineered surface treatments

In this work, the most efficient and common engineered surface treatments identified as shot peening (SP), laser shock peening (LSP) and ultrasonic surface rolling process (USRP) were utilized to impact the 300 M ultrahigh strength steel. The microstructure evolution and surface strengthening behavior were carefully characterized and compared for the 300 M steel with various treatments. Besides, the underlying mechanisms for difference in grain refinement and surface mechanical properties by the arranged surface modification are revealed. The results indicate that a gradient structure with nano-grains at the top surface appears on the SP, LSP and USRP treated samples. The process of repeated impacts of SP in different directions leads to activation of multiple slip systems, which thus causes severe refined grains and dense dislocation activities associated with dislocation tangles, dislocation walls and blocking. A great variety of strikes per unit area by USRP results in higher plastic deformation compared to SP where numerous dislocation cells and deformation bands were generated. In contrast to SP and USRP, fewer slip systems are activated in LSP due to the short duration time which thus leads to the thinnest refined grain layer and more planar dislocation structures. The combination of low plastic work and lack of refined grains leads to lowest full width at half maximum (FWHM) in case of LSP samples whereas high FWHM comes from both fine grain size and dislocations in SP. The grain refinement and plastic work contributes to an increase of microhardness and compressive residual stress for the SP, LSP and USRP samples. To be clear, SP leads to a higher magnitude of hardness and compressive residual stress on the topmost surface while LSP causes a larger depth due to that shock wave in LSP influences material to much greater depth. Besides, the decomposition and redistribution of carbides are also noticed on the surface layer after the surface treatments with very high strain rate where numerous dislocations accumulate at the border of the carbides and slip trace is also observed within the carbides.

Enhanced strength-plasticity synergy of 304 stainless steel by introducing gradient nanograined single austenite phase structure via USRP and induction annealing

The drawback of low strength of 304 stainless steel could be overcome by fabricating gradient nanostructures (GNS). However, deformation-induced martensite results in magnetic generation and plasticity degradation. In this work, a single austenitic GNS 304 stainless steel is fabricated by first creating a dual-phase GNS through the ultrasonic surface rolling process (USRP), followed by rapid induction heating. The yield strength of the single austenite GNS (520 MPa) is 1.68 times higher than that of the homogeneous coarse-grained structure (310 MP) without sacrificing plasticity (elongation of 65 %). Quantitative calculations indicate that fine grain, dislocation, twinning, and back-stress strengthening contribute to the strength increment by 30 %, 17.5 %, 23.4 %, and 29.1 %, respectively. Coarse-grained regions deform mainly through FCC-HCP-BCC martensitic transformation, whereas the subsurface layer forms stacking faults and twins due to increased stacking fault energy caused by the reduction in grain size. At the topmost layer, the stress required to activate dislocations is lower than that for twinning. Under high-stress conditions, martensite forms along the nanograin boundaries via a phase transition from FCC to BCC. Consequently, the excellent plasticity of the single austenite GNS stems from the synergistic effects of high back-stress hardening, TRIP and TWIP effect.

Effect of corrosion on the fatigue damage behavior of M50 steel treated by ultrasonic surface rolling process

Ultrasonic surface rolling process (USRP) can improve the fatigue performance of M50 steel, but corrosion during service may affect the anti-fatigue performance. Microstructure and corrosion resistance of M50 steel treated by USRP is analyzed by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). Besides, the fatigue behavior of USRP sample under corrosion is analyzed by conducting fatigue tests after immersion corrosion tests. Results show that USRP treatment refines the surface grains to nanoscale (29.8 nm), introduces a certain residual compressive stress and decrease the precipitations of M50 steel, which improve the density of passive film and the resistance to local corrosion for M50 steel. Compared to M50 steel matrix, USRP sample has fewer and smaller corrosion pits at the same corrosion time, thereby reducing the risk of crack initiation. Meanwhile, the residual compressive stress value of USRP sample remains at a higher level. So the fatigue life of USRP sample is always higher than that of untreated sample under the same corrosion time. However, the corrosion process still leads to the destruction of surface integrity and the release of residual compressive stress, and the fatigue performance of USRP sample will gradually decrease with increasing the corrosion time.

Corrosion evolution of 316L stainless steel after ultrasonic severe surface rolling and laser shock peening processing

Laser shock peening induced smaller grain size than ultrasonic severe surface rolling for 316L stainless steel. Furthermore, laser shock peening processing facilitated to induce more strain induced α′-martensites. Therefore, the refined grains and α′-martensite enhanced significantly the hardness of 316L stainless steel. Moreover, laser shock peened sample exhibited better corrosion resistance than ultrasonic severe surface rolled one in a medium containing chloride ions. Although α′-martensite would decrease passivation and anti-corrosion ability of 316L stainless steel, the grain refinement promoted the diffusion activity of chromium element, which accelerated surface passivation process.

Study of Quenching and Partitioning (Q&P) and Ultrasonic Surface Rolling (USR) Process on Microstructure and Mechanical Property of a High-Strength Martensitic Steel.

Steel with a combination of strength and plasticity is prevalently demanded for lightweight design and emission reductions in manufacturing. In this study, a high-strength Cr-Ni-Mo martensitic steel treated by quenching and partitioning (Q&P) and ultrasonic surface rolling (USR) processes was studied for both strength and plasticity enhancement. Specimens were austenitized at 850 °C and then quenched to 240 °C via cooling by water, oil, and normalization in quenching. This was followed by partitioning, in which two groups of specimens were heated to 370 °C and 350 °C for 45 min, respectively. At last, all the specimens were quenched to room temperature with the same methods of quenching. The highest tensile strength increased from 681.73 MPa to 1389.76 MPa when compared to as-received (AR) steel after the Q&P process. The USR process with a static force of 800 N further improved the tensile strength of specimens with high tensile strength after the Q&P process, which improved from 1389.76 MPa to 1586.62 MPa and the product's strength and elongation (PSE) increased from 15.76 GPa% to 15.9 GPa%, while the total elongation showed a mitigatory decrease from 11.34% to 10.02%. Tensile fractures were also studied and verified using a combination of strength and plasticity after a combined process of Q&P and USR.

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 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.

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.

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.