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In this article, the yield strength, tensile strength, and the microstructure of the wrought aluminium alloy 7449 rolled thick plate have been studied through thickness under different temper conditions. For all heat treatments, it has been proven that the yield strength and tensile strength values increase from the surface to the centre. The largest difference between the centre and the surface, in both properties, occurs in the case of a sample aged at room temperature for 120 h (TTA temper). The sample artificially aged at 120 °C for 24 h (TTB temper) shows the best strength-gradient relationship of the tensile properties through the thickness. Metallographic characterisation carried out by optical and scanning electron microscopy shows much finer elongated grains in the region near the surface of the plate than in the centre, with incipient recrystallisation in the area near the surface. In addition, electron backscattered diffraction technique, used for micro-texture analysis, has proven the presence of a gradient of crystallography texture in the plate. This explains the yield strength gradient, since the rate of change of the Taylor factor through thickness correlates with the rate of the change of yield strength in the longitudinal direction for the samples studied. [ABSTRACT FROM AUTHOR]

In this work, the effect of laser shock peening (LSP) on the electrochemical behavior of HSLA steel (ASTM A 588 Grade D) in 3.5 wt.% NaCl solution was investigated. The microstructural evolution, micro-texture development, surface roughness, residual stress development, microhardness, dislocation density, potentiodynamic polarization, and electrochemical impedance spectroscopy were studied in depth. The corroded surfaces (with and without LSP) were characterized using scanning electron microscopy and Raman spectroscopy for understanding the nature of the passive film formation and its stability. The results revealed that LSP treatment marginally refines the near-surface microstructure from 9.1 to 7.4 μm and generated high compressive residual stress (CRS) of about 500 MPa on the top surface; such variation happened due to severe plastic deformation during LSP. The micro-texture analyses of the laser-peened specimens (on the surface) revealed that {011} <111> texture components were significantly increased while the γ-fiber weakened after laser-peening. Dislocation density was obtained ~ 9.266 × 1012 on the unpeened and ~ 1.158 × 1013 on the laser-peened surfaces, indicating that higher pressure shock waves plastically deformed the top layer of the peened specimen. The corrosion studies indicated about 4 times improvement in the corrosion resistance of the peened specimens—the combined effects of LSP-induced gradient CRS and refined microstructure improved the corrosion resistance. The EDS and Raman spectroscopy results demonstrated the persistence of a compact and continuous passive oxide film/layer, primarily made of Fe2O3, on the surface of the laser-peened specimens. [ABSTRACT FROM AUTHOR]

In order to solve the problems of serious tool wear and poor processing quality in the process of titanium alloy processing, cutting-edge dulling and surface texturing technology are applied to improve the service performance of cutting tools. Designing multiple density micro-textured tool according to the friction form of the tool-chip contact area is an essential factor in ensuring the cutting performance of tool. In this paper, firstly, the influence of laser parameters on the temperature field and stress field of the material is analyzed, and the optimized laser parameters are obtained. Secondly, the experimental milling platform of multiple distribution density micro-texture ball-end milling cutter under the action of cutting edge is built. The influence of micro-texture and cutting-edge parameters on tool milling performance and work-piece quality is analyzed, and the mechanism is revealed. Finally, the parameters are optimized based on the simulated annealing algorithm. The results show that the main parameters affecting the milling force, tool wear, and work-piece surface roughness are the edge radius and the micro-texture diameter of the stickiness area. It has opened up new ideas for the efficient cutting of titanium alloy. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the micro-texture and plastic anisotropy of a dual phase steel. A DP800 steel was produced by cold rolling and intercritical annealing of a low carbon steel. Micro-texture analysis on the DP800 steel by means of electron backscatter diffraction revealed that a high orientation density exists along the α and γ fibers. However, the overall texture intensity was not significant. Tensile testing of the DP800 steel at different angles to the rolling direction demonstrated a very low dependency of tensile properties and work hardening behavior to the loading direction. Nevertheless, the r-value showed some directionality with a mean value of 0.851, suggesting a substantial anisotropy for the studied DP800 steel. [ABSTRACT FROM AUTHOR]

Laser-induced plasma-assisted ablation (LIPAA) is a promising microfabrication method. In the experiment, a piece of transparent material (quartz) was placed above the absorption material (copper plate). The effects of laser fluence, repetition rate, and scan speed on the results and their mechanism were analyzed. The changes of micro-texture size, copper content, and contact angle (CA) on quartz surface were discussed. The micro-texture height keeps between 2.6 and 3.1 μm when the repetition rate increases to 2.5 MHz. The micro-texture size increased with the laser fluence and decreased with the scan speed. The copper content reached a maximum of 39% at 1.91 MW/cm2 and 2.5 MHz. The quartz surface processing area achieves hydrophobic performance without any post-treatment. The CA reached its optimal value of 146° at 900 mm/s and 2 MHz. There is a correlation between hydrophobicity and micro-texture size. The research results can provide a reference for optimizing the LIPAA parameters of quartz. The studied LIPAA method can potentially be employed for the fast and effective fabrication of hydrophobic surfaces without post-treatment. [ABSTRACT FROM AUTHOR]

The stress field redistribution at the tool–chip interface of micro-textured tools was examined. The effect of stress field redistribution on the cutting performance was also investigated, including cutting forces, friction characteristics, and chip morphology. The findings have shown that the main cutting forces were reduced by 18% through the decrease of average shear strength and tool–chip contact area. The equivalent average friction coefficient ua deceased from 0.66 to 0.64 with the groove texture width increasing from 80 to 140 μm. The chip deformation coefficient also decreased from 3.4 to 2.77 with the increase of groove texture width, which was mainly attributed to the improvement of friction characteristics at the tool–chip interface. In order to characterize the stress field redistribution at the tool–chip interface, an improved theoretical model of stress field redistribution for micro-textured tool was proposed based on Zorev's assumption. The stress field was assumed as zero in the groove texture zone and had a maximum local stress because of the appearance of derivative cutting. The proposed model was validated by the calculations of normal and friction forces. Combined with the theoretical calculations and experimental findings, the results have shown that with the increase of groove texture width, the decrease of normal and shear stress in the groove texture zone was enlarged. And the increase of normal and shear stress, caused by derivative cutting, was reduced. Then, under the combined effect of groove texture and derivative cutting, the friction characteristics at the tool–chip interface can also be improved. The present findings give more insight in to the stress field redistribution of micro-groove textured tools and the underlying friction mechanisms at tool–chip interface. [ABSTRACT FROM AUTHOR]

It is difficult to machine with high machining efficiency and surface integrity for SiCp/Al composite, especially for those with a high volume fraction of SiC. Here, we present monolayer brazed diamond grinding wheels that contain different micro-textures ablated by pulse laser. The dry grinding characteristics of SiCp/Al composites with 70 vol.% SiC using the wheels with different micro-textures were investigated. The influence of micro-textures on the grinding force, grinding temperature, and surface integrity was examined. The results indicated that micro-textures on diamond grits can induce cleavages and form more micro-cutting edges in grinding of SiCp/Al. The wheel contains both micro-grooves and micro-hole and owns the lowest grinding force, grinding temperature, and surface integrity. The micro-textured wheel produces smaller grinding chips and less fracture, crushing, and pull-out of SiC particle on the ground surface of SiCp/Al composites than other wheels. [ABSTRACT FROM AUTHOR]

The surface integrity of machined workpiece is an important index to evaluate the service performance of parts. In order to improve the service performance and machining efficiency of titanium alloy, the concept of variable distribution density micro-textured ball end milling cutter is proposed based on texture effect. Firstly, based on the ball end milling model of titanium alloy, a variable density micro-texture model is established in the chip contact region. Secondly, a milling titanium alloy test platform was built to reveal the change law and mechanism of micro-texture parameters on the machined surface integrity. Finally, based on the hierarchical structure weight method and fuzzy comprehensive evaluation theory, the integrity of the machined surface is comprehensively evaluated and the micro-texture parameters are optimized. The results show that the variable distribution density micro-texture has a positive effect on improving the machining quality of titanium alloy. The micro-texture in the bonding zone can reduce the tool-chip contact area, improve the friction state, increase the heat dissipation area, and reduce the plastic deformation of titanium alloy. The micro-texture in the slip zone can improve the chip curl and promote the stability of the system. In addition, reasonable micro-texture parameters can obtain better surface quality of the workpiece. [ABSTRACT FROM AUTHOR]

Difficult-to-machine materials such as Ni-based superalloy suffer from severe tool wear and poor surface quality; therefore, the cooling mechanism is the key to improving machining performance and reducing the environmental pollution in manufacturing. In the past, plenty of studies verified that the micro-texture on the cutting insert improved the cutting performance under the same cooling condition. The main explanation is that the second generated cracks caused the capillary siphon phenomenon and increased the wettability of the subsurface of the workpiece. In order to investigate the effect of surface wettability differences on the cutting performance of the tool under different micro-textured morphologies, three types of micro-textured CBN tools with pit, linear, and sinusoidal morphologies were fabricated by laser machining technology. Through cutting experiments on Inconel 718 Ni-based superalloy, the cutting force, tool wear, and machined surface roughness of different micro-textured tools were compared and analyzed. The relationship between cutting performance and wettability of different shaped micro-texture was obtained by measuring the contact angle using PT-705B optical angular contact meter. The experimental results show that the presence of surface micro-textures enhances the surface wettability of the tool. It effectively reduces the cutting force and slows down the rake face's wear and the machined part's surface roughness. Compared with other morphologies, sinusoidal micro-textured tools show the best cutting performance. Among the four morphologies of micro-textured tools, cutting performance improvement increases with surface wettability. More generally, these primary findings are consistent with research showing that wettability is critical in micro-texture generation for high-performance machining. The conclusion is very much the key component in future attempts to overcome the assumption of the capillary siphon phenomenon on the subsurface of the workpiece. [ABSTRACT FROM AUTHOR]

Road pavements are exposed to traffic loading and external deterioration agents which both can compromise tire-pavement interactions, posing a threat to road safety. The surface wear generates crushed pavement materials or tire rubber wear particles which, combined with other contaminants, negatively impact the environment. In fact, these particles may remain on the road surface; adhere to tires; become airborne; or drain by rainfall to roadsides, waterways, lakes, and even open oceans. Therefore, the presence of road contaminants on road infrastructure pavements is a concern for both road safety and the environment. Although the condition of pavement, traffic intensity, airborne dust emissions, and roadside environments are significantly monitored by road practitioners, especially in urban areas, there is still a need to better evaluate the pollutants remaining on road surfaces. It is known that particles smaller than 40 μm can be trapped within micro-asperities and remain on road surfaces, while particles of larger sizes can be transported by rainfall. However, it is difficult to mobilize particles with sizes larger than 105 μm by storm water runoffs, which tend to remain on road surfaces. Hence, not only rainfall characteristics are responsible of particle's kinetics, but also particle's size and road surface roughness are important. Therefore, this paper presents an overview of road safety and environmental concerns around contaminants, highlighting the importance of the road surface characteristics in their behavior. Finally, the current methods to measure road surface characteristics and their application for environmental and safety issues are discussed. [ABSTRACT FROM AUTHOR]

The continuous optimization of processing technology and evaluation methods is an important way to achieve high processing quality and processing efficiency for difficult-to-process materials. To solve the problem of frequent defects in the slot, the ultrasonic vibration-assisted slot-milling (UVASM) technology was developed for processing titanium alloy. Simultaneously, comparative experiments were carried out between UVASM and conventional slot milling (CSM), in terms of surface features of slot bottom and slot sidewall, cutting force, tool trajectory, chip morphology, and micro-hardness. The results show that uniform vibration micro-texture could significantly improve surface topography of slot bottom in UVASM, while numerous tool feed trajectories and observable machining defects detract from the surface quality in CSM. The UVASM can greatly reduce material spalling and edge breakage, thereby maintaining a smooth and regular edge profile of the slot sidewall. The tool tip trajectories of the two machining methods are highly corresponding to the machining textures of the slot sidewall surface. There is a high-frequency and small-amplitude force fluctuation signal on the axial force waveform in UVASM, which can reduce the instantaneous maximum milling force and milling force in the stable stage by 8.7 and 12.2%, respectively. The UVASM has a better chip breaking effect and surface anti-scratch effect, and the UVASM can obtain higher surface micro-hardness and deeper plastic deformation layer than those CSM. In summary, the multi-dimensional evaluation of slot processing status has been completed, and the processing quality of the slot has been improved. [ABSTRACT FROM AUTHOR]

Although axial ultrasonic vibration-assisted milling (AUVAM) is promising for rapid and economical fabrication of 3D micro-texture on various surfaces, it has been a challenge to obtain micro-texture with small feature size and large height simultaneously. The mechanism and major influence factors for the formation of micro-texture by this method were explored in this study. It was found that the generation of micro-texture was mainly caused by cutting and extrusion from the flank face of the milling tool under ultrasonic vibration. Therefore, a novel 3D tool model that considered the relief angle, end cutting edge angle and the blade profile was established in simulation analysis. The good agreement between simulation and experimental results demonstrated that the influence of the flank face on the micro-texture was mainly attributed to the relief angle of the milling tool. It was the first time to report that both the height and the profile shape of the micro-texture unit were affected by the overlap and extrusion between the flank surface and the micro-texture. But this influence diminished with the increase of spindle speed. 3D sinusoid-shaped micro-texture with minimum width of 20 μm and height of 2 μm (fully reproduced the ultrasonic amplitude) was realized with the relief angle of 40° and spindle speed of 4000 rpm. Other typical textures of weave, shell, scale and corrugation were also presented to show the effective regulation of texture patterns in AUVAM. This work provides both theoretical and practical basis for such a low-cost, efficient and controllable 3D micro-texture preparation method. [ABSTRACT FROM AUTHOR]

High strength steel sheets of thinner sections are being widely adopted in automotive industries for lightweighting purposes. However, dent resistance of steel sheets reduces with its thickness but increases with its surface yield strength. In this work, we explore the possibility of improving the strength of a sheet metal surface by a micro-texturing process with the aid of finite element simulations. Micro-texturing is expected to increase the strength of the surface because of the inherent size effect of the material and consequently improve the dent resistance. The mechanical responses of such a micro-texture, consisting of an array of rectangular micro-features, are studied for different loading conditions. A higher order strain gradient plasticity theory is employed to analyze the size effect of the micro-texture, under a small strain 2D finite element framework. The influence of the different geometrical features of the micro-texture and the length scale parameter of the material on the mechanical response, are investigated and the implications of these results on the dent resistance are discussed. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of composite nano-Cu/WS2 lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool's rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS2 lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS2 lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions. [ABSTRACT FROM AUTHOR]

Due to the wide applications of aluminum alloy in numerous industrial sectors and products, significant attention has been paid by many researchers to improve the production and manufacturing aspects of aluminium alloys and related products. One of the main concerns in this regard is the cutting tool life when machining aluminium alloys. This work aims to present the capability and performance analysis of a new strategy of life improvement in the tungsten carbide inserts by creating micro-textured grooves on their surface. For this purpose, the laser was used to create the different morphologies of textures on the insert surfaces. The grooves were created with different distances in parallel to the cutting edge on the tool rake face. The effects of fabricated grooves on the tool wear attributes were discussed in three directions, including the main edge (x-direction), side edge (y-direction), and radial (in the direction of 45°), and the effect of these grooves/textures on the surface roughness attributes was also studied. To that end, experimental works were performed under dry and minimum quantity lubrication (MQL), as well as three levels of cutting speed, feed, and grooves distance. The experimental results were compared with those measured under non-textured inserts. Finally, the obtained results were statistically analyzed, and the empirical models were formulated. Experimental results indicated that micro-textured inserts in both MQL and dry conditions led to surface quality and tool wear as compared to readings made under non-textured inserts. [ABSTRACT FROM AUTHOR]

This study is about basing on the optimized area occupied, which affects cutters' cutting performance, the cutting performance of the tool is optimized. In order to obtain the best area to be occupied by a micro-texture for cutting performance, a micro-texture area occupancy model for a cutter's rake face was established and finite element simulation was used to analyze the influence of different degrees of micro-texture on the strength of a cutter's structure. The impact of different mesoscopic geometric parameters on the cutting performance was then analyzed. By using an SVR algorithm, the test data was optimized and the best cutter area occupancy was obtained on the basis of the TOPSIS optimization method. The mesoscopic geometric characteristic parameters were then optimized using a Genetic Algorithm. The test results showed that the placement of the micro-texture did not affect the structural strength of the cutter and the optimum area occupancy rate was 18.99%. The optimum diameter for the micro-texture was found to be 59.79 μm, with a spacing of 126.46 μm, a distance from the cutter edge of 100.20 μm, a cutter edge radius of 58.95 μm, and a micro-texture area occupancy of 18.12%. The double optimization of the characteristic parameters enabled them to mutually verify one another, facilitating the rapid design of cutters and indicating the best way of obtaining highly efficient machining for materials such as titanium alloy. [ABSTRACT FROM AUTHOR]

Tool surface temperature distribution and tool wear are important parameters in the cutting process. It is important to reduce the wear degree of tool surface for tool life. In this paper, a semi-elliptical profiling tool is designed according to the shape of ellipse and compared with three other tools with different shapes, and the effects of different shape parameters on the temperature and wear of Ti-6Al-4V cutting process are discussed. The contact angle of chip and texture and the direction of chip flow are compared, and the following shape parameters are discussed: tip distance, texture size, and distance to each micro-texture. The effects of these parameters are evaluated in terms of temperature and wear. It is found that the semi-elliptical tool designed according to the shape of ellipse can effectively reduce the wear depth and the surface temperature of the tool, and it is more stable for the variation of different texture parameters. We found that the elliptical micro-textured/grooved cutting tool has good stability and can face a variety of working conditions. [ABSTRACT FROM AUTHOR]

In this study, the numerical model of LST process using pulsed laser system is established, in which the absorption coefficient of laser energy by the cemented carbides was determined through comparing finite element analysis and experiments results. And then the numerical model is verified through LST experiments. Finally, the relations between LST parameters and depth/width ratio and HAZ/width ratio are analyzed. The results showed that within the parameters' ranges studied in this paper, the laser energy absorption coefficient for cemented carbides decreases with the increase of the laser frequency and increases with the increase of laser power. Scanning speed has almost no effect on the absorption coefficient. As for the influence of laser parameters on the parameters of the micro-groove, it is found that laser power has the greatest influence on the HAZ/width ratio, followed by laser frequency and scanning speed. In contrast, laser parameters have no significant influence on the depth/width ratio of the micro-groove. The optimum laser parameters should be chosen after the requirement of the micro-groove parameters. [ABSTRACT FROM AUTHOR]

The control variable method is a method to study the influence of a certain factor on the result quantity by artificially controlling other factors. Some researches have shown that a micro-texture can effectively reduce the surface work-hardening degree of the tool surface. Therefore, in this study, based on the control variable method, a micro-texture ball-end milling cutter was used to mill titanium alloy. The influence rules of micro-texture distance from edge, micro-texture distribution type and mode and cutting stroke on work hardening degree were analysed. The results show that the surface work-hardening degree was the smallest(118%) at a distance of 90 μm from the cutting edge and at a 0.3° offset angle. When the micro-texture is micro-pit texture, the work hardening degree is 121% and is minimum. The content of the O element in the surface modification layer of the micro-textured tool is 6.97%, which is less than 16.17% of that of the non-textured tool, and the content of the C element is 4.95% and 4.97% respectively. The results show that the micro-texture placement can effectively reduce the oxidation degree and work hardening degree of the machined surface of the milled titanium alloy. [ABSTRACT FROM AUTHOR]

In this paper, a removable through-mask electrochemical micromachining (EMM) is proposed for fabricating the microstructures with different sizes and structures on the inner surface of the hybrid bearing. By optimizing the machining parameters of EMM, micro-textures with considerable area consistency and excellent surface quality are obtained on the inner surface of the hybrid bearing. Subsequently, the stability tests of the non-textured bearing and other three textured bearings with various area ratios are carried out on the setup of hybrid rotor-bearing system to study the influence of micro-texture on the vibration characteristics and stability of the bearing rotor. The time domain, frequency domain, and axis trajectory of the rotor are compared and analyzed. The experiment results show that at low speed (2400 rpm), the micro-texture has little effect on the amplitude of bearing-rotor system. As the rotational speed increases, the amplitude of the rotor-bearing system gradually increases. It should be noted that the amplitude of specific micro-texture bearings is smaller than the non-textured bearing, but not all types of micro-texture perform like that. At 9000 rpm, the relative amplitude of one sample decreases by 22.6% compared with the non-textured bearing rotor system. Therefore, the micro-texture with reasonable size and structure could significantly reduce the vibration of the rotor-bearing system under the water film condition, which is of considerable significance to improve the stability of liquid film and provides a potential application background for high-speed bearing lubrication. [ABSTRACT FROM AUTHOR]

Wear behavior of micro-textured insert with lubrication was studied. Micro-pits with different diameters (80–200 μm), depths (3–10 μm), and area occupancies (10–30%) were manufactured on the tool rake face near the main cutting edge. Experimental research was conducted to reveal the effect of micro-pits on tool-chip interface friction characteristics. Besides, the texture parameter with better tribological characteristics was selected to study the wear mechanism of textured insert. Scanning electron microscopy analysis was conducted on the worn area of rake face. The results confirmed that the micro-textures can effectively reduce the average shear strength of rake face and actual tool-chip contact length during machining. The best average friction coefficient can be obtained with texture diameter of 170 μm, depth of 7 μm, and area occupancy of 20%. Adhesive wear, diffusion wear, and oxidation wear appeared on the worn area of rake face. The micro-textures can effectively reduce the diffusion wear and suppress the built-up edge (BUE) by improving tool-chip interface friction characteristics. The findings are of significance for enhancing the application of textured insert with excellent tribological characteristics. [ABSTRACT FROM AUTHOR]

Given the serious work hardening phenomenon, high chemical activity, severe tool wear, and poor workpiece surface quality during the cutting of titanium alloys, placing micro-texture on the tool surface decreases the tool-chip contact area and friction and plays the role of wear resistance and friction reduction. In order to improve the cutting performance of cutting tools, the present study examins the effect of micro-texture parameters of a cemented carbide ball-end milling cutter on cutting force, tool wear, and workpiece surface roughness and establishes a regression analysis model via regression analysis. We consider the cutting performance of a cemented carbide micro-texture ball-end milling cutter as an evaluation standard. A genetic algorithm is applied to the multi-objective optimization of micro-texture parameters, and a regression analysis model of micro-texture design criteria is established. This provides a standardised reference to select standard micro-texture parameters in the design and preparation of a cemented carbide micro-texture ball-end milling cutter. [ABSTRACT FROM AUTHOR]

Titanium alloys is a typical difficult-to-cut material with many machining problems, build-up-edge, large cutting force, and high cutting heat. Previous research has shown that micro-texture on the tool surface can solve the above problems potentially, and that a blunt round edge of the cutting tool can enhance its strength and improve the tool wear resistance. Therefore, towards an optimal parameter of micro-texture and blunt round radius, a finite element method (FEM) simulation and an experiment are carried out, where the test result provides a set of data for a genetic algorithm–based prediction model. The optimized parameter combinations of the micro-textured ball-end milling cutter with a blunt round edge are obtained and compared in a set of experiments. The optimized parameters refer to a 40-μm radius of the blunt round edge, a 40-μm micro-texture diameter, a 175-μm spacing, a 120-μm distance from the cutting edge, and an 80-μm depth. [ABSTRACT FROM AUTHOR]

Setting the micro-texture in the cutter–chip contact area of a micro-textured tool rake face can effectively improve the tool's cutting performance. However, an unreasonable design for the micro-groove morphology and size and the selection of inappropriate cutting parameters will cause a secondary cutting phenomenon during the cutting process. To explore the optimum micro-texture morphology size and cutting parameters, micro-texture self-lubricating ceramic cutting tools with different morphology parameters (micro-texture location distribution: MSTD-1, MSTD-2, MSTD-3; groove spacing: MSTS-1, MSTS-2, MSTS-3; groove width: MSTW-1, MSTW-2, MSTW-3) were formed in situ and by hot pressing sintering, and a dry cutting 40Cr comparison test with a non-textured tool (MST-0) was conducted. The results revealed that the MSTD-2 tool effectively reduced the cutting force, friction factor, and rake face wear and relieved the secondary cutting phenomenon while cutting 40Cr. A theoretical analysis showed that the micro-texture morphology parameters and cutting speed were the main factors affecting the secondary cutting, with a smaller groove width and higher cutting speed associated with a lighter chip impact. [ABSTRACT FROM AUTHOR]

In recent years, surface textures in micron scale is introduced into the rake face of cutting tools to facilitate the lubricant penetration into the cutting area and improving the friction conditions between tool-chip contact area. The penetration process of lubricant into micro-textures introduced into the rake face of the cutting tool during machining process is analyzed through theory calculation, FEA analysis and penetration experiments. It is found that the initial penetration velocity increases as the size of the micro-texture decreases; However, due to the combined effect of capillary pressure and friction force, the penetration distance for micro-texture with larger size is longer than that for micro-texture with smaller size when the penetration distance is larger than 0.15 mm; micro-texture with smaller size is suitable for smaller chip width, 0.15 mm under the conditions in this study, and micro-texture with a larger size is more effective for large back engagement in consideration of lubricant penetration. Also, an optimum size of micro-texture on the rake face of cutting tools should take both lubricant penetration and strength of the cutting tool into consideration. The results of this study would benefit for the designation of micro-textures in the future. [ABSTRACT FROM AUTHOR]

Charge welds occur in profiles during billet-to-billet extrusion of hollow aluminum profiles. To investigate the effects of charge welds on the tensile property of the profile, a tensile test and a fracture scanning test using the scanning electron microscope (SEM) are conducted. The results showed that charge weld plays bad roles in the tensile property of the profile. The tensile samples derived from the charge weld distribution zone are always fractured near the charge welds. In addition, the tensile strengths of the early-stage charge welds are the poorest. To validate the property variations in the charge weld zone along the extrusion directions in a microscale, the evolution of microstructure characteristics and texture in the charge weld distribution zone are discussed with the help of the electron back scattering diffraction (EBSD). The grain morphologies, misorientation, and micro-textures are not uniform along the charge weld in the extrusion direction or on different sides of itself. Incomplete dynamic recrystallization with lower distortion energy and dislocation density due to lack of frictions with dies at the beginning and middle stages of the charge weld results in strip-shaped coarse grains and lower-angle grain boundaries, further revealing the essence of the low tensile strength at the beginning and in the middle of the charge weld. The intensity of shear texture {111}<112> on the charge weld is the largest compared with those on both sides of it, verifying the large plane strain status on the charge weld plane. [ABSTRACT FROM AUTHOR]

Micro-textures on cutting tool surface have been reported for their benefits in terms of reduction of adhesion, wear, force and friction during the cutting process. However, these benefits are dependent on the micro-texture parameters. This paper presents an experimental study on the effect of micro-textures during orthogonal cutting of aluminium, aiming to determine a suitable parameter combination. Micro-textures were fabricated on the rake face of tungsten carbide (WC) cutting tools by a picosecond laser. Circular dimples were selected as the texture unit cell, and the parameters included diameter, depth, pitch and distance from the cutting edge. Experiments were conducted by varying these parameters using the Taguchi method. Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to find the optimal levels of the selected parameters and to study the effect of the micro-textures on cutting forces, shear angle, contact area as well as adhesion of aluminium. It is found that diameter was the most influential parameter based on the factors taken into consideration. Then, a confirmation test using the derived levels of texture parameters was carried out to demonstrate the effectiveness of the micro-texture. The best combination of texture parameters was identified considering all the responses and the range of parameters. [ABSTRACT FROM AUTHOR]

Pavement surface friction is a significant factor for driving safety and plays a critical role in reducing wet-pavement crashes. However, the current asphalt mixture design procedure does not directly consider friction as a requirement. The objective of this study was to develop a surface friction prediction model that can be used during a wearing course mixture design. To achieve the objective, an experimental study was conducted on the frictional characteristics of typical wearing course mixtures in Louisiana. Twelve wearing course mixtures including dense-graded and open-graded mixes with different combinations of aggregate sources were evaluated in laboratory using an accelerated polishing and testing procedure considering both micro-and macro texture properties. In addition, the surface frictional properties of asphalt mixtures were measured on twenty-two selected asphalt pavement sections using different in situ devices including Dynamic Friction Tester (DFT), Circular Texture Meter (CTM), and Lock-Wheel Skid Trailer (LWST). The results have led to develop a procedure for predicting pavement end-of-life skid resistance based on the aggregate blend polish stone value, gradation parameters, and traffic, which is suited in checking whether the selected aggregates in a wearing course mix design would meet field friction requirements under a certain design traffic polishing. [ABSTRACT FROM AUTHOR]

Parametric optimisation of micro-texture is important to improve the performance of cutting tool in metal cutting. In this study, the simulation models of micro-textured surface of cemented carbide are established by using ABAQUS platform, and fictitious stress distribution is analysed to select the optimum micro-texture structure. Then, many friction tests were carried out to compare the several different micro-textures. Based on the experimental data, the parametric optimisation model of micro-texture on cemented carbide surface is established, and its significant analysis is carried out. Moreover, the optimised parameters are applied to the ball-nose end mill in the machining of titanium alloy. The results show that the micro-texture can absorb stress and change the status of stress distribution on the surface. Among the micro-texture structures, the performance of micro-pit is the best one, i.e. surface stress micro-pit-texture is distributed uniformly, and the stress concentration micro-pit-texture is low, when the micro-pit-texture’s diameter is 46.6 μm, its depth is 27 μm, and its distance is 123 μm. The ball-nosed end mill with the optimised parameters has a stronger wear resistance than a normal tool. [ABSTRACT FROM AUTHOR]

The skid resistance performance of pavement is closely related to the micro-texture of pavement aggregate, while there is very few research on the relationship between micro-texture and the skid resistance. In this paper, the optical microscope is used to acquire the surface morphology of three types of aggregates including basalt, limestone and red sandstone respectively, where a total of 12 indicators are developed based on the surface texture information. The polishing effect on aggregate is simulated by Wehner/Schulze (W/S) device, during the polishing procedure, the skid resistance are measured by British Pendulum Tester (BPT). Based on the results of independent T-test and the polishing resistance analysis, it shows that the surface texture of basalt is significantly different between limestone and red sandstone. Three indicators including the average roughness ( Ra), the kurtosis of the surface ( Sku) and the mean summit curvature ( Ssc) are selected to describe the characteristics of aggregate micro-texture based on the correlation analysis. The contribution of micro-texture to the skid resistance can be described with the secondary polynomial regression model by these indicators. [ABSTRACT FROM AUTHOR]

Three kinds of aggregates were polished by genuine pneumatic rubber tyres. The initial states of surface texture and dynamic friction coefficient were measured and their developments in polishing process were monitored. The characterizations of height distribution and power spectral density of aggregate surface texture were estimated. The changes of micro-texture were also investigated based on a fractal filtering method with sound theoretical backgrounds of rubber friction on rough surfaces. Global height reduction and differential removal of mineral component are observed in polishing process. It is concluded that the tyre-polishing action plays the critical roles in the micro-scale texture, and the evolution of friction of aggregate is governed by the micro-texture changes due to the differential removal of mineral component. [ABSTRACT FROM AUTHOR]