Roll Surface Research Articles

Comparative studies of welded joints of rails after various hardening methods

The paper studies changes in temperature and pressure during hardening using the factory and upgraded sprayer of the UIN cooling system. The hardness distribution was studied for one- and two-sided cooling. The analysis of the obtained results shows that the greatest decrease in hardness is observed at a distance of 50 mm from the weld center. These points are the heat-affected zone from the action of the inductor of the induction unit. According to the regulatory documentation, a decrease in hardness of up to 15% is allowed during heat treatment of a welded joint compared to the hardness of the base metal. The results were obtained after upgrading the induction unit cooling sprayer in terms of expanding the hole zone and increasing the diameter of the holes in the lower shelf of the sprayer. The hardness measurement results indicated the shortcomings of induction heating during local heat treatment with a one-sided air distribution system on an induction unit of the UIN-001-100/RT-S(P) type. It was necessary to modify the cooling sprayer design to increase the intensity of the compressed air flow and to ensure uniform distribution of the air flow velocity onto the rail head. Also, to achieve an air flow rate of at least 200 m/s in the upper hardening unit, it is necessary to change the compressor unit control system. The sprayer modification allowed to increase the intensity of the hardening device operation in the central area of the rail head and the heat-affected zone from the inductors. The modification of the upper hardening unit ensures uniform distribution of the air on the rolling surface of the head during hardening and uniform distribution of hardness in the central area of the head, in the areas of the rail fillets, in the transition zones. This will eliminate the defect of chipping and crushing of the rail head metal during the operation of welded joints.

Research on the optimal laser preparation process parameters of groove-shaped micro-texture on the mill roll surface

Laser micro-texture preparation technology significantly excels in micro-texture processing, yet there has been scant reported research on utilizing this technology for micro-texture processing and texture morphology control on the surface of wheat mill rolls. The aim was to ascertain the ideal laser preparation process parameters for the creation of groove-shaped micro-textures on the surface of the chilled alloy cast iron, serving as the surface layer material of the wheat mill roll. An experiment was conducted using a nanosecond pulsed fiber laser to explore the impact of laser power, scanning times, scanning velocity, and pulse frequency on the morphology and dimensions of the groove-shaped micro-textures. It was found that with laser power set at 7 W, 15 scanning times, a pulse frequency of 35 kHz, and a scanning speed of 500 mm/s, the desired microgroove can be successfully fabricated on the surface of the mill roll. The findings of this study offer insights for the surface modification of critical components in grain and oil machinery and equipment through the application of laser micro-texturing technology.

Adhesion of Aluminum Alloy to Tip of Nozzle Plate of Vertical Type High Speed Twin Roll Caster

In a vertical type high-speed twin-roll caster, the adhesion of solidified aluminum alloy to the nozzle (ASAN) makes problems with the quality of the strip surface. The effects of the Si content of Al–Si alloys and the casting conditions on the ASAN were investigated. Alloys with Si contents of 0%, 0.5%, 1%, 2%, 3%, 6% and 10% were considered. The ASAN was high for Si contents of 0.5%, 1%, and 2%. This demonstrates that there is a relationship between the quasi-solid state and the ASAN. As the roll speed and molten metal temperature increased and solidification length decreased, the ASAN decreased. On the basis of these results, the stagnation of molten metal near the nozzle plate was investigated. A gap of 5 mm was introduced between the nozzle plate and the roll surface to eliminate the stagnation of molten metal, resulting in reduction of the ASAN.

Experimental investigation on the initiation and propagation of corrosion fatigue cracks in EA4T axle steel treated by ultrasonic surface rolling

Experimental investigation on the initiation and propagation of corrosion fatigue cracks in EA4T axle steel treated by ultrasonic surface rolling

Enhancing surface integrity and corrosion resistance of 18CrNiMo7-6 gear steel via integrating carburized treatment and ultrasonic surface rolling process

Enhancing surface integrity and corrosion resistance of 18CrNiMo7-6 gear steel via integrating carburized treatment and ultrasonic surface rolling process

Effect of ultrasonic surface rolling extrusion on microstructural evolution and wear resistance of laser-clad CoCrFeMnNi high-entropy alloy with low stacking fault energy

Ultrasonic surface rolling extrusion (USRE) was employed to strengthen face-centered cubic (FCC) phase CoCrFeMnNi high-entropy alloy (HEA) coatings prepared by laser cladding. The influence of USRE's static load on the microstructure, mechanical properties, and wear resistance of the coatings was examined to elucidate the grain refinement mechanism. The findings indicate that USRE preserves the phase composition of the CoCrFeMnNi HEA coatings. After USRE at loads of 100 N, 200 N, and 300 N, the measured thicknesses of the severe plastic deformation layers are 2.51 μm, 3.03 μm, and 3.45 μm, respectively. The process triggers dislocation multiplication, which accumulates at the boundaries of Mn-rich regions, forming dislocation cells and evolving into subgrains, thereby refining the grain structure under severe plastic deformation. Statistical analysis reveals that the dislocation density within the grains is 7 × 1014 m−2, while at the grain boundaries, the dislocation density is 4 × 1015 m−2. The average grain size has been refined from 97.7 μm to 34.7 μm. Both microhardness and wear resistance escalate with increased static load, with the maximum microhardness of 347 HV and the minimum wear rate of 2.6 × 10−5 mm3·N−1·m−1 achieved at a 300 N static load. This hardness enhancement is due to the combined effects of grain refinement, dislocation strengthening, and sub-grain formation. The wear mechanisms for the USRE-treated CoCrFeMnNi HEA coatings include adhesive wear, abrasive wear, and oxidative wear. While adhesion and abrasion diminish with higher static pressures, oxidative wear intensifies.

Preparation and Characterization of Al2O3/h-BN Composite Coatings by Atmospheric Plasma Spraying (APS)

To improve the adhesion strength of polymer functional films, corona treatment is required. Corona rollers are key components for corona treatment, which are used in high-voltage electric fields for a long time. In this work, in order to improve electrical insulation, arc resistance, wear resistance, and chemical stability, a coating is usually sprayed on the surface of the corona roller. Al2O3/h-BN composite coatings are prepared on the surface substrate of a corona roller (20 steel) by atmospheric plasma spraying (APS) technology. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis showed that the Al2O3/h-BN composite coating had a layered structure and compactness. Two kinds of Al2O3/h-BN composite coatings are prepared under different APS process parameters; the porosities of A coating and B coating are 6.04% and 4.75%, the microhardnesses are 781 ± 0.5 Hv and 840.5 ± 0.5 Hv, and the adhesion strengths are 22.0 MPa and 22.3 MPa, respectively. The A and B volume resistivity of the coatings are 9.29 × 1010 Ω·cm and 3.55 × 1010 Ω·cm, respectively. The volume resistivity and porosity of the coatings are negatively correlated, and they decrease with the increase in spraying current. But for both coatings, volume resistivity is greater than 1 × 1010 Ω cm. These results indicate that the Al2O3/h-BN composite coatings, as a new type of electrode roller coating, satisfy the use requirement. Al2O3/h-BN composite coatings can become the potential for ceramic coatings that have good mechanics and insulation performance.

Research on Ni-WC Coating and a Carbide Solidification Simulation Mechanism of PTAW on the Descaling Roll Surface

The descaling roll is a critical component in a hot-rolling production line. The operating conditions are significantly impacted by water with high-pressure and dynamic shocks caused by high-temperature steel slab descaling. Roll surfaces often experience wear and corrosion failures. This is attributed to a combination of high temperatures, intense wear, and repeated thermal, mechanical, and fluid stresses. Production costs and efficiency are significantly affected by the replacement of descaling rolls. Practice shows that the use of plasma cladding technology forms high-performance coatings. Conventional metal surface properties can be significantly improved. In this study, a Ni-WC composite coating was prepared on the descaling roll surface by plasma-transferred arc welding (PTAW) technology. The microstructure and phase composition of the welding overlay were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results show that the WC hard phase added to the molten pool dissolves, and subsequently M7C3 and W2C phases are formed. To further explore the morphological evolution mechanism of the hard phase, numerical simulations were performed using a phase-field method to model M7C3 phase precipitation. The evolution from nucleation, rod-like growth, to eutectic structure formation was revealed. Experimental and simulation results show high consistency, validating the established phase-field model. In this study, a theoretical foundation for designing and preparing high-performance coatings is provided.

Surface texture transfer in skin-pass rolling under mixed lubrication

This paper presents a novel integrated approach to modeling surface texture transfer in skin-pass rolling under mixed elasto-plasto-hydrodynamic lubrication (EPHL). The innovation lies in combining discrete fast Fourier transform (DC-FFT) for precise characterisation of elastically deformed asperities on the roll surface, dynamic explicit finite element analysis (FEA) for capturing cross-scale deformations, and a transient average Reynolds equation for governing the lubrication flow. By integrating these methods, the model addresses the complex interplay between elastic roll deformation, microscale asperity-lubricant interactions, and elastoplastic strip deformation, providing a more comprehensive understanding of texture transfer mechanisms. In addition, the model predictions are validated by experimental results. Furthermore, this study investigates the effects of rolling speed and surface pattern orientation, revealing that higher speeds reduce texture transfer while surface patterns aligned with the rolling direction enhance it. These insights demonstrate the potential of this integrated modeling approach for advancing the field of skin-pass rolling.

Effect of Multi-pass Ultrasonic Surface Rolling Process on Surface Properties and Microstructure of GCr15 Steel

Effect of Multi-pass Ultrasonic Surface Rolling Process on Surface Properties and Microstructure of GCr15 Steel

CFD Simulation and Surface Modification of SG Cast Iron for Hot Rolling Applications

The wear resistance and heat dissipation of hot rolling mill rollers are critical factors affecting their durability and operational efficiency, particularly under extreme thermal and mechanical conditions. This study investigates the surface modification of SG iron rollers through tungsten laser cladding, aiming to improve these properties. A comprehensive approach, combining Computational Fluid Dynamics (CFD) simulations and experimental trials, was employed to evaluate the performance of tungsten-cladded rollers relative to untreated ones. The results revealed a 10-18% improvement in heat dissipation for tungsten-cladded rollers, attributed to enhanced heat transfer rates and better cooling efficiency. The analysis of fluid flow patterns, water volume fraction, and cooling angles demonstrated that tungsten cladding allowed for more effective heat management and uniform cooling across the roller surface. In the experimental trials, the mechanical properties of SG iron showed significant enhancement after laser cladding. The microhardness of the cladded surface increased by 59%, from 220 HV to 350 HV, offering improved resistance to surface deformation and wear. Furthermore, the wear resistance improved by 35% reduction in wear loss, as the tungsten and MoS₂/WC composite coatings provided a strong protective barrier against abrasion. Additionally, the Coefficient of Friction (COF) was reduced by 43%, from 0.7 to 0.4, due to the lubricating properties of MoS₂, minimizing frictional heat and energy loss during operation. These findings reveal the effectiveness of tungsten laser cladding as a surface modification technique for SG iron rollers, with practical implications for improving the durability and operational efficiency of hot rolling mill rollers.

Optimization of working parameters of high-pressure roller mill based on entropy weight method and response surface method

In order to improve the crushing efficiency of high-pressure roller mill and reduce energy consumption, the optimal parameter combination of high-pressure roller mill is sought, GM160-140 high-pressure roller mill is taken as the research object, and the discrete element simulation calculation model of high-pressure roller mill is established to simulate the crushing process. Taking the roll surface pressure, productivity, and the proportion of discharge particle diameter as the performance evaluation indexes, the simulation data are used to analyze the influence of each working condition parameter of the high-pressure roller mill on its performance law. Through the entropy weighting method to determine the weights of high-pressure roller mill productivity, roll surface pressure, the proportion of discharge particle diameter, and through the extreme difference analysis to get the optimal parameter combination. Minitab software is used to carry out the response surface method (RSM) experimental design, the optimal parameter combinations are derived from the optimization using the response surface apparatus, the optimal parameter combinations derived from the two optimization methods are compared and analyzed, and ultimately it is concluded that the optimization of the response surface is the global optimal, and the optimal parameter combinations are as follows: the roller speed is 2.50 rad/s, the roller gap is 28.87 mm, and the feed size is 31.97 mm, Under the above optimal parameters, the roll surface pressure is 150450.00 N, the productivity is 1268.00t/h, the percentage of the material less than 6 mm is 58.14%, so as to achieve the purpose of optimizing the parameters of the high-pressure roller mill, It is of significance to save resources and respond to the national green development and intelligent development.

Effects of ultrasonic surface rolling process on the microstructure and wear resistance of 2195 Al-Li alloy processed by laser powder bed fusion

This study presents a comparative analysis of the impacts of surface rolling (SR) and ultrasonic surface rolling (USR) techniques on the microstructure and wear resistance of 2195 Al-Li alloy processed by laser powder bed fusion (LPBF). The results show that both SR and USR processes induced grain refinement, increased dislocation density, and converted tensile residual stress into compressive residual stress in the surface layer of the original samples. Compared to the SR process, the USR process exhibited more pronounced strengthening effects due to its unique acoustic effect and dynamic recrystallization mechanism. With the application of USR, the average coefficient of friction for the sample reduced from 0.41 to 0.32. This enhancement in wear resistance can be attributed to the synergistic effects of grain boundary strengthening, dislocation strengthening, and stress strengthening mechanisms.

Kinetics of elastic recovery in roll compaction

Elastic recovery (ER) has been investigated and discussed extensively in the field of tableting. However, until now only limited data is available regarding ER in roll compaction. Therefore, a previously established in-line measurement technique was rolled out to further investigate the kinetics of ER in roll compaction and the effects of specific compaction force (SCF) and roll speed (RS). In-line laser triangulation measurements at different positions within a roll rotation as well as measurement over time after the process has been stopped were utilized. Pure microcrystalline cellulose (MCC) and two placebo powder blend formulations were analysed. Successful fit of the contained ER profiles emphasized that the ER on the roll surface is build out of two exponential kinetics. Starting with a dominating fast ER (ERA), characterized by a high increase of the ribbon thickness after passing the gap width, followed by a slower ER (ERB). Sigma minus plot analysis showed that increasing RS led to an accelerated ERA and ERB which was related to the viscoelastic behaviour of MCC. The SCF only had an effect on the kinetics of ER if a brittle filler was added to the mixture. The conducted study established the first approach in literature to characterize the kinetics of ER in roll compaction. It supports the understanding and characterization of relaxation times and the effect of the RS and SCF in roll compaction.

Simultaneously achieving strength-ductility in additive-manufactured Ti6Al4V alloy via ultrasonic surface rolling process

Additively manufactured alloys have a great potential in engineering field, but there still have many issues to be addressed, i.e., the reliability, strength-ductility trade-off of manufactured parts. In this study, a treatment called ultrasonic surface rolling process (USRP) was utilized to achieve superior strength and ductility in the Ti6Al4V alloy prepared via electron beam melting (EBM). The treated additive-manufactured alloy obtained various gradient microstructures and excellent surface quality, as well as its mechanical properties were significantly improved. Especially, the USRP-3 specimen exhibited a high elongation of 17.1 ± 0.9 % and a good ultimate tensile strength of 1043 ± 5.0 MPa, which were both higher than those of untreated specimen; the fine laminated structure with a preferred orientation of (101‾0) direction and gradient structure promoted the hardening capacity and provided the rich dislocations sources, taking a better strength-ductility combination. In addition, the surface microhardness of the multi-pass processed specimen was markedly enhanced. However, excessive USRP treatment would induce micro-cracks in the nano-composite layer, resulting in a significant reduction in ductility. Therefore, appropriate USRP treatment is expected to expand the application range of additive-manufactured metallic materials.

Influence of Ultrasonic Surface Rolling on the Tensile and Fatigue Properties of Laser-Cladding-Repaired 300M Steel Components

Abstract Herein, to address the issue of decreased tensile and fatigue performances observed in 300M steel scratched parts after laser-cladding repairing, an ultrasonic surface rolling process (USRP) was employed to enhance the strength of the laser-cladding-repaired (LCR) samples. Results indicated that USRP led to the formation of a strengthening layer on the surface of the samples. In the parent material area, the thickness of the strengthening layer was 180 μm, while in the cladding area, it was 35 μm. The superficial microhardness increased by 11.6% in the parent material area and by 5.0% in the cladding area. Furthermore, the surface residual stress transitioned from tensile to compressive stress, reaching a maximum of 1169.9 MPa. Improvements were observed in the tensile performance, as evidenced by a reduction in the length of the tearing ridge in the fracture morphology. In addition, the fatigue life considerably increased, initially increasing and then decreasing as the number of rolling passes increased. After four cycles of USRP, the fatigue life of the samples was the highest, which was about 18.4 times that of an unprocessed sample. The origin location of cracks shifted from the surface to the interior of the samples. This shift was accompanied by a decrease in the instantaneous fracture area and the emergence of additional secondary cracks. These experimental results demonstrate that USRP is an effective technique for improving the tensile and fatigue performances of LCR 300M steel samples.

Microstructure and tribological property of laser cladding Stellite 6 alloy by laser remelting and ultrasonic surface rolling

Stellite 6 alloy was deposited onto the surface of 27SiMn steel using the laser cladding (LC) technique, which was then followed by laser remelting (LR) and ultrasonic surface rolling (USR).The surface roughness, microstructure, microhardness, surface residual stress, and wear resistance of LC, LR, and LR-USR samples were studied using electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray stress analyzer, Vickers hardness tester, and material surface performance tester. The results showed that compared with LC, LR-USR significantly refined the surface dendrites of the cladding layer, with the average dendrite size decreasing from 16.37 μm to 6.92 μm. After USR, the samples converted from tensile residual stress (TRS) to compressive residual stress (CRS), and the high-density dislocations and strain generated in the grains near the surface of the cladding layer. The wear depth volume of the LR-USR samples was the smallest, showing typical abrasive wear.

Role of dry media in influencing performance during processing by centrifugal superfinishing

ABSTRACT To achieve better surface quality and higher efficient finishing of AISI 52,100 steel cylindrical roller surfaces, a novel dry medium was prepared, which is composed of millimeter-sized adsorptive medium matrix and polishing paste containing micron-sized abrasives. The study utilized centrifugal superfinishing to examine the effects of dry media with various abrasive types, sizes, and polishing paste ratios. The influence of these dry media on the processing performance was comprehensively evaluated, covering parameters including material removal rate, roughness decrease rate constant (K r ), roughness limit (Ra lim ) value, surface morphology, and profile. In addition, the processing mechanism was revealed. This study provides valuable insights into the development and performance regulation of new media for nano-level superfinishing of complex surfaces.

Effect of aged treatment on improving the performance of HVAF WC–Cr3C2–Ni coating on crystallization roller

The thermal shock resistance and high-temperature performance of WC–Cr3C2–Ni coatings on the surface of the crystallization roll after aged treatment were investigated in this study. The aging treatment at 320 ℃ for 2.5 h facilitated the diffusion of Cu element from the C17200 beryllium copper substrate toward the coating side of WC–Cr3C2–Ni coating, thereby enhancing the bonding between the coatings and substrates. After the aged treatment, the internal structure of the C17200 substrate changed from a dendritic structure to an equiaxed crystal structure, the hardness increased from 225.71 Hv0.5 to 406.52 Hv0.5 (80.4 % increased), and the wear resistance increased.Although the aging treatment reduced the hardness of the coating slightly (from 1257.58 Hv0.5 to 1155.16 Hv0.5, a decrease of 8.1%) and wear resistance (the coefficient of friction, from 0.335 to 0.312, a decrease of 6.9%). However, in the thermal shock test, the thermal shock resistance of the coating after aging treatment was increased from 19 times to 20 times (5.3% increased). However, the thermal shock failure cracks between the coatings and the substrates were transferred from the substrate part to the joint part of the two, which effectively avoided the waste of the crystallization roller substrate in the maintenance process. This research effectively reduces the purchase and maintenance costs of steel mills in actual production and provides theoretical support for cost reduction and efficiency increase in other HVAF (high-velocity air fuel) coating applications.

Durability of deterministic textures produced by maskless electrochemical texturing (MECT) during Skin pass cold rolling

Skin pass is a fundamental finishing process to control the sheet roughness in cold metal rolling. The energetic and tribological efficiency of this process can be improved by surface texturing to control the roll surface topography and consequently the final sheet roughness. In this work, deterministic textures were produced on flat segments of skin pass rolls using the maskless electrochemical texturing (MECT) technique. The textures consisted of arrays of circular dimples. After texturing, the specimens were coated either with hard chrome or NiP electroless coatings, aiming to evaluate the ability of electroless NiP coating to protect textures as a potential replacement of the carcinogenic hard chrome coating. The evaluation of the texture durability was carried out via dry reciprocating sliding tests with samples extracted from cold rolling work rolls. The test configuration and conditions were chosen to intensify the wear process in order to evaluate the durability of the textures during skin pass cold rolling. Wear evaluation was also by analyzing changes in roughness parameters. The results indicated that the best tribological performance occurred for the textured surfaces coated with NiP. The average coefficient of friction of the textured surfaces coated with NiP was around 16 % lower than that of the uncoated textures and around 19 % lower than that of textures coated with hard chrome coated. Although the mass loss was negligible in the tests, the analysis of surface topography parameters showed that both hard chrome and electroless NiP coatings acted to decrease the wear of MECT textured surfaces.