Ultrasonic Surface Rolling Process Research Articles

Insights into the Response Differences of Ultrasonic Rolled A3 Carbon Steels and 316L Stainless Steels to Scale and Wax Precipitation Behavior

AbstractIn this work, the antiscaling and antiwaxing properties are evaluated by surface roughness testing, water contact angle measurements, scale and wax deposition testing, and potentiodynamic polarization analysis, respectively. The morphologies and microstructures of the samples before and after ultrasonic surface rolling process (USRP) are analyzed by scanning electron microscopy and optical microscopy, respectively. The results show that for 316L stainless steel after USRP, its surface roughness and surface energy decrease by 97% and 27%, respectively, and the average scale amount is decreased by 73% and antiwaxing rate is up to 63%. In contrast, for the A3 steel after USRP, the average amount of scale and wax deposition increases due to the enhanced atomic activity of the surface layer and surface energy although its reduced surface roughness. It is found that the lower surface energy is the primary factor for improving the antiscaling and antiwaxing performance. A second factor may be related to the smooth surface and superior corrosion resistance.

Effect of twin assisted precipitation on the microstructure and mechanical properties of gradient structure Mg-Gd-Zn-Zr alloy

Nano-precipitation can effectively pin the dislocations and inhibit the dislocations’ motion, making precipitation strengthening one of the most crucial strengthening mechanisms in magnesium (Mg) alloys. Consequently, controlling the segregation of elements at the coherent interfaces to induce the phase precipitation, has become an innovative way of designing Mg alloys. In this study, a novel twin-precipitation composite gradient structure GZ151K (Mg-15Gd-1Zn-0.4Zr) alloy was prepared using ultrasonic surface rolling process (USRP) and heat treatment. The results indicated that the USRP-treated samples subjected to aging treatment demonstrated high thermal stability without significant twin degradation. Additionally, the twin boundaries and grain boundaries could act as the nucleated points for the (Mg, Zn)5Gd phases during the subsequent aging treatment, and further formed the twin-precipitation composite gradient structure. This unique composite gradient structure of alloys treated by USRP and aging treatment was caused by an extra promotion-precipitation strengthening mechanism. Under the effects of promotion-precipitation strengthening, strain hardening, and precipitation strengthening, the mechanical properties of the GZ151K alloy were significantly improved.

Thermal stability of nanocrystalline surface layer in an aged Al–Zn–Mg–Cu alloy induced by ultrasonic surface rolling processing

This paper investigates the thermal stability of nanocrystalline surface layer in an aged Al–Zn–Mg–Cu alloy fabricated by ultrasonic surface rolling process (USRP). The microstructure of the nanocrystalline surface layer and the microstructure changes of grains and precipitates in the nanocrystalline surface layer after annealing at various temperatures were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. The microhardness after annealing was also analyzed. The results show that a nanostructured lamella with a thickness of about 40 nm was prepared in the surface layer of the aged Al–Zn–Mg–Cu alloy after USRP. The granulation of the nanostructured lamellae occurs during subsequent annealing due to recovery and becomes more significant with the increase of annealing temperature. Besides, the coarsening η phases occur at the lamellae boundaries by heterogeneous nucleation. Meanwhile, the precipitate inside lamellae gradually changes from GP zone and η' phase to η phase. The thermal stability of the nanostructured lamellae is excellent below 160 °C, but it deteriorates significantly when the temperature exceeds 200 °C. The hardness variation of the nanostructured lamellae is mainly determined by the variation of lamellae thickness and the precipitation behavior plays an auxiliary role.

Improved corrosion resistance of 42CrMo4 steel by reconstructing surface integrity using ultrasonic surface rolling process

The ultrasonic surface rolling process (USRP) was adopted to improve the corrosion resistance of 42CrMo4 steel by reconstructing the surface integrity in terms of surface roughness, microhardness, residual stress, and microstructures. The corrosion behaviors of 42CrMo4 steel were studied by salt spray corrosion, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results indicated that the surface integrity of 42CrMo4 steel was restructured after USRP with the surface roughness reduced to 0.052 µm, the surface microhardness improved to 305 HV0.1, the residual compressive stress achieved up to − 274 MPa at 0.6 mm depth, and the average grain diameter minimized to 2.02 µm in the zone of 5–150 µm depth. Owing to the modified surface roughness, hardened layer, and induced residual compressive stress, the corrosion resistance of 42CrMo4 steel was enhanced by USRP with the annual corrosion rate of 2.972 mm/a reduced about 5.2 %, the corrosion current density of 2.748 μA·cm−2 decreased up to 45.2 %, and the charge transfer resistance of 1809 Ω·cm2 increased up to 19.6 %.

Effect of ultrasonic surface rolling process on the fretting tribocorrosion behaviors of Inconel 690 alloy

The ultrasonic surface rolling process (USRP) is conducted by making the metal surface undergo micro-plastic deformation to improve its surface state and some mechanical properties, thus strengthening its tribocorrosion resistance. In this study, the surface of the Inconel 690 alloy block was treated by special USRP, and the change in its tribocorrosion behaviors had been effectively revealed by a fretting electrochemical corrosion test rig. Results showed that the Inconel 690 alloy’s tribocorrosion degree and corrosion rate were evidently reduced after USRP. These results could be attributed to the surface finish reduction and surface grain refinement caused by USRP.

The Grey-Taguchi method analysis for processing parameters optimization and experimental assessment of 42CrMo steel treated by ultrasonic surface rolling

Static force, ultrasonic amplitude, feed rate, and rolling spacing parameters of 42CrMo steel treated by the ultrasonic surface rolling process (USRP) were optimized by the Grey-Taguchi method. Nine sets of experiments based on an orthogonal array design and grey relational analysis were used to obtain the optimum combination of mechanical properties for USRP. The influence of processing parameters on mechanical properties was investigated based on the grey relational analysis. The results indicated that the feed rate is the dominant parameter affecting the mechanical properties, followed by rolling space, ultrasonic amplitude, and static force. The effects of plastic strain caused by USRP on the compressive residual stress and microhardness were investigated. The effects of the dislocation and cementite evolution on the mechanical properties were investigated to determine the origin of the best and worst mechanical properties. For the best mechanical property, the level and depth of distribution of compressive residual stress and tensile strain hardening capacity are the highest, which is benefited from the optimum synergistic of the elastic-plastic deformation, dislocation evolution, gradient distribution, and cementite evolution. For the worst mechanical property, a large amount of cementite is distributed within and around martensitic laths, increasing brittleness and the lowest comprehensive mechanical properties. These findings can provide a reference for accurately controlling the processing parameters of USRP and improving their mechanical properties.

Improved fretting fatigue mechanism of surface-strengthened Ti-6Al-4V alloy induced by ultrasonic surface rolling process

Surface plastic deformation methods are prevalently applied to improve the fretting fatigue (FF) property of titanium alloys. Understanding the intrinsic relation between surface plastic deformation severity and the FF property is of great significance to the application of these methods. Here, the influence of surface plastic deformation severity on the FF behavior of Ti-6Al-4V alloy is investigated. Two different levels of surface plastic deformation severity are prepared at the surface of Ti-6Al-4V alloy by employing ultrasonic surface rolling process. Uniaxial FF tests illustrate that both of the deformed samples have improved FF properties and although their fatigue life is comparable, the influences of their refined microstructures and compressive residual stresses are different. Pre- and post-mortem microstructural analyses reveals that the grains are coarsened or crystallized from amorphous material at the topmost surface under the multiaxial stresses to accommodate the plastic strain for the high surface deformation severity, while the grains are refined at the subsurface for the low surface deformation during FF loading.

Influence of residual stress and its relaxation on the corrosion bending fatigue resistance of EA4T axle steel treated by ultrasonic surface rolling

The fatigue properties and residual stress relaxation behavior of EA4T axle steel treated by ultrasonic surface rolling process (USRP) are investigated in air and corrosive environments. The result reveals that the surface roughness (Ra) is decreased from 1.42 to 0.17 μm after the USRP. A surface layer with ultrafine grains, work hardening, and compressive residual stress (CRS) is achieved by the USRP. Compared with the as-machined specimens, the USRP specimens exhibit slightly lower electrochemical corrosion resistance but superior fatigue performance in air and corrosive environments. The dislocation density is significantly decreased in the corrosive environment during fatigue loads, accompanied by a rapid relaxation of surface CRS. The influence of USRP on the corrosion fatigue performance is elucidated. The residual stress relaxation mechanism and its influence on fatigue resistance are also analyzed.

Achieving the synergistic of strength and ductility in Mg-15Gd-1Zn-0.4Zr alloy with hierarchical structure

Currently, the hierarchical structure is one of the most effective means to enhance the strength and plasticity of metal materials, since the strain localization can be effectively delayed by the coordination of the unique microstructure. In this study, a hierarchical structure of Mg-15Gd-1Zn-0.4Zr (GZ151K) alloys containing grain, twin, and precipitation structural units was prepared by ultrasonic surface rolling process (USRP) and recrystallization annealing (RU). The results showed that the stress gradient generated by USRP formed a twin gradient structure, which will activate the twin-assisted precipitation (TAP) effect and twin-induced recrystallization (TIR) effect during RU. Then, the twin gradient structure transformed into a twin-precipitation gradient structure, and finally into a hierarchical structure with grain-twin-precipitation as the increasement of recrystallization degree. Besides, the dual gradient structure with twin and precipitation structural units had the highest strength and microhardness owing to the precipitation strengthening. However, the hierarchical structure with grain, twin, and precipitation structural units exhibited the most excellent combination of strength and plasticity under grain refinement and precipitation strengthening.

Improved rolling contact fatigue performance of selective electron beam melted Ti6Al4V with the as-built surface using induction-heating assisted ultrasonic surface rolling process

In this paper, the effects of induction-heating assisted surface ultrasonic rolling processing (IH-USRP) on the rolling contact fatigue (RCF) performance of selective electron beam melting (SEBM) built Ti6Al4V was evaluated with respect to surface integrity, chemical composition, and microstructure were investigated. At the room temperature (RT), the surface roughness and line roughness (Ra and Rz) of the USRP treated sample are reduced by 92 % and 95 %, 78 %, and 66 % compared to the untreated sample, respectively, and the surface hardness is also increased by 17 %. The surface quality and hardness are further improved when samples treated by IH-USRP, and the oxide mixture could be found on the sample surface. The surface roughness and line roughness (Ra and Rz) of the IH-USRP treated sample at 650 °C were reduced by 96 % and 98 %, 85 %, and 83 %, respectively, while the surface hardness was 33 % higher than that of the untreated one. The surface quality improvement reduces the stress concentration, and the increased surface hardness means higher critical shear stress, which promotes the average RCF life by 196 %.

Effect of a gradient structure on the mechanical performance of Inconel 718 Ni-based superalloy at elevated temperatures

The effect of a gradient structure (GS) with present precipitates on the tensile properties of Inconel 718 (IN718) alloy at elevated temperatures was studied. A high-density δ-Ni3Nb phase and fine recrystallized γ grains were obtained in the surface gradient layer using an ultrasonic surface-rolling process (USRP) and subsequent heat treatment. The amount of the δ phase in the gradient layer decreased with the layer depth, while the size of the recrystallized γ grains exhibited an opposite trend. Remarkably, the GS did not show a microhardness gradient at room temperature but exhibited excellent strength and plasticity during high-temperature tensile tests. Compared with a uniform sample, the yield strength (YS) and ultimate tensile strength (UTS) of the specimen with a GS increased by 55 and 105 MPa, respectively, and the plasticity increased by 25% in the tensile tests at 650 °C. The δ phase pinned the RANS-scale grain hierarchy in the gradient layer and improved the thermal stability at 650 ℃. This GS promoted the accumulation of high-density geometrically necessary dislocations (GNDs) in the gradient layer during plastic deformation, resulting in additional back-stress strengthening. Therefore, forming a gradient structure with precipitates provides a new approach toward a good combination of strength and ductility at elevated temperatures.

Comprehensive Analysis of the Effect of Ultrasonic Surface Rolling Process on the Friction and Wear Properties of TB8 Titanium Alloy

Comprehensive Analysis of the Effect of Ultrasonic Surface Rolling Process on the Friction and Wear Properties of TB8 Titanium Alloy

Effect of ultrasonic surface rolling process on the surface properties of CuCr alloy

A nanocrystalline surface layer was fabricated on the surface of CuCr8 alloy by surface ultrasonic rolling treatment (USRT) with different rolling depth. The surface morphology, microstructure, hardness, surface strength and corrosion resistance were systematically characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and the corresponding test methods. The results showed that the USRT treatment did not change the surface phase of the CuCr8 alloy, but only refined the surface grain. The rolling depth had great influence on the surface properties of the CuCr8 alloy. When the rolling depth was 0.15 mm, the surface comprehensive performance was the best. The surface grain size was about 78 nm, the surface hardness was up to 120 HV0.05, the tensile strength reached to 400 MPa, and the corrosion performance was significantly enhanced. The content of Cr, CuO and Cu(OH)2 in the passivation film of the USRT treated alloy was higher than that of the CG alloy. The USRT treatment provides a new method for fabricating CuCr alloy vacuum break tubes with high surface properties.

Surface Microstructure Refinement and Mechanical Properties of GCr15 Steels Improved During Ultrasonic Surface Rolling Processing

In this paper, ultrasonic surface rolling processing (USRP) was used to strengthen GCr15-bearing steel. A finite element three-dimensional model of USRP was established to analyze the residual compressive stress and equivalent plastic strain distribution on the bearing steel surface. The microstructure, hardness, surface roughness, and corrosion resistance before and after USRP treatment were characterized by SEM, EBSD, X-ray diffraction (XRD), and electrochemical techniques. Results indicated that USRP treatment can significantly improve the material's surface microstructure and residual compressive stress distribution and obtain a plastic strain layer of about 60μm. After USRP treatment, the Kernel Average Misorientation (KAM) increased, and the dislocation activity was more intensive, resulting in aggregation near grain boundaries, and the percentage of LAGBs increased to 38.8%. Under the combined effect of surface grain refinement, residual compressive stress, and high glossy surface, the self-corrosion current density is reduced by two orders of magnitude, and the corrosion resistance is significantly improved. This investigation suggests a solution to the bearing failure problem and has implications for understanding the deformation mechanism of ultrasonic surface rolling processing.

Anti-Fouling Behaviors of a Modified Surface Induced by an Ultrasonic Surface Rolling Process for 304 Stainless Steel

This research aimed to investigate the effects of an ultrasonic surface rolling process (USRP) on the deposition behaviors in CaCO3 crystallization fouling for 304 stainless steel (304SS). The microstructure, surface morphology, and hydrophobic properties of the modified layer were characterized with optical microscopy, a roughness profile measurement instrument, and a contact angle measurement instrument. The corrosion and fouling behaviors of different surfaces were studied in simulated cooling water. The polarization curves and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical properties. The results showed that USRP-treated surfaces had better anti-corrosion and anti-fouling performance. The improvement in anti-fouling performance was attributed to the weakening of peaks and valleys, the reduction of surface defects, and the improvement of corrosion resistance.

Enhanced corrosion resistance of laser additive manufactured 316L stainless steel by ultrasonic surface rolling process

The ultrasonic surface rolling process (USRP) was adopted to strengthen the surface corrosion resistance of laser additive manufactured 316L stainless steel (LAMed 316L), and the strengthening mechanism of USRP on corrosion resistance was studied with various static pressures. The surface integrity and corrosion behaviors of LAMed 316L were analyzed by the tests of surface roughness, microhardness, residual stress, electron backscatter diffraction (EBSD), Xray diffraction (XRD), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S), Xray photoelectron spectroscopy (XPS), and three-dimensional microscope, respectively. The results indicated that the LAMed 316L after USRP obtained the reduced surface roughness up to 95 %, the improved microhardness up to 53 %, the introduced residual compressive stress up to −212 MPa, and the decreased grain diameter about 16 %. The LAMed 316L treated by USRP under the static pressure of 200 N presented the supreme corrosion resistance with the corrosion current density decreased up to 41 %, the polarization resistance increased up to 34 %, and the donor and acceptor densities reduced about 51 % and 81 %, respectively. The corrosion resistance of LAMed 316L was strengthened by USRP, benefiting from the modified surface roughness, grain refinement, increased Cr2O3 content in the passive film, work hardening, and residual compressive stress.

Layer-by-layer analysis of gradient corrosion behavior of ultrasonic rolling-processed 20CrMnTi steel

The gradient corrosion behavior of 20CrMnTi treated by the ultrasonic surface rolling process (USRP) was investigated by layer-by-layer analysis. As the nanostructured layer gradient changed from the surface to the interior, multiple electrochemical behaviors were studied at different depths in a neutral corrosive environment. The results showed that the corrosion resistance of the deformed layer underwent a nonmonotonic transition. Although the outer surface exhibited excellent corrosion resistance, this resistance decreased sharply and reached a minimum at a depth of 50 μm. This study showed that the corrosion resistance at different depths was mainly influenced by the density of low-angle grain boundaries (LAGBs) rather than by the grain size. The highest LAGB density was observed at depths of 30–50 μm, resulting in the greatest lattice distortion that induced the lowest corrosion resistance.

Theoretical and numerical investigation of micro-textures fabrication by ultrasonic surface rolling process

Surface texturing is a potential approach to achieving excellent surface performance. To realize high precision and efficiency in micro-texturing fabrication, a surface texturing method utilizing an ultrasonic surface rolling process is proposed. Firstly, the feasibility and geometric controllability of micro-texture preparation using ultrasonic surface rolling process are analyzed. Then, a contact theory model of ultrasonic rolling texturing process is established, which can describe the geometric relationship of the micro-texturing generation region. Based on the elastic–plastic theory, simulations of single-pass and multi-pass ultrasonic rolling texturing processes are developed to elucidate the formation and strengthening mechanism of micro-textures, and further characterize the effects of ultrasonic rolling machining parameters on micro-textures. A series of validation tests of ultrasonic rolling texturing are implemented on AISI 5140 steel. Simulation and experimental results show that the ultrasonic surface rolling process can fabricate micro-groove arrays with the periodic distribution. The validity of the theoretical and finite element models is confirmed by the comparison results. It is demonstrated that the ultrasonic rolling texturing process is a feasible and efficient way to fabricate controllable micro-textures.

Improved low-temperature mechanical properties of FH36 marine steel after ultrasonic surface rolling process

The ultrasonic surface rolling process (USRP) was adopted to improve the low- temperature mechanical properties of FH36 marine steel for strengthening the service performance of marine steel in the low-temperature environment between − 30 °C and − 60 °C, such as polar regions. The results indicated that the surface integrity of FH36 marine steel was restructured as a result of the severe plastic deformation induced by USRP. The surface average grain diameter was refined from 10.92 µm to 5.86 µm with the number of nanoscale grains increased significantly and a nanostructured surface layer formed. The surface roughness decreased greatly with Ra not more than 0.074 µm. The surface residual compressive stress with an affected layer depth of not less than 2.6 mm was produced. The surface microhardness increased significantly with a large-depth work hardening layer of not less than 580 µm. The yield strength and ultimate tensile strength of FH36 marine steel after USRP at room temperature and low temperatures were enhanced. The combined effects of fine grain strengthening, dislocation strengthening, modified surface roughness, induced residual compressive stress, work hardening, and changed heat transfer performance caused by USRP were the main reasons for the improved low-temperature mechanical properties of FH36 marine steel.

Numerical modeling considering initial gradient mechanical properties and experiment verification of residual stress distribution evolution of 12Cr2Ni4A steel generated by ultrasonic surface rolling

Ultrasonic surface rolling process is a promising surface strengthening technique which can improve the fatigue performance of metallic components by introducing reasonably compressive residual stress field. It is of great significance to accurately predict the residual stress distribution of parts in the simulation of ultrasonic surface rolling process. In this paper, a numerical model considering initial gradient mechanical properties (residual stress and micro-hardness) is proposed to predict the residual stress distribution of 12Cr2Ni4A carburized and quenched steel. Moreover, a method is proposed to calculate the ultrasonic surface rolling coverage based on Hertz contact theory, which can guide the optimization of process parameters. The effects of static load, rolling tool radius, amplitude and feed rate on residual stress distribution are investigated. The simulated results and measured results are compared and proved to be in good agreement, which validates the accuracy of the model proposed in this paper.