Built-up Layer Research Articles

Effects of the size of built-up layer on the wear of cemented carbide tools in cutting of SUS304 stainless steel

Effects of the size of built-up layer on the wear of cemented carbide tools in cutting of SUS304 stainless steel

High temperature wettability and oxidation behavior of TiN, Ti–Al–N and Ti–Si–N PVD film

In aluminium cutting and die casting, tools are exposed to Built UP Edge (BUE) and Built Up Layer (BUL) and erosion due to the frequent contact of the tool surface to the aluminum alloy, to oxidation due to high temperatures. For this reason, the susceptibility to reaction with liquid aluminum and stability of TiN, Ti–Al–N and Ti–Si–N films were investigated using wetting test, high temperature oxidation experiment and complementary differential scanning calorimetry. The results show that the type of chemical bond affects the surface tension, tool steel with metal bonds is most easily wetted, after being wetted and cooled by molten Al at 725 °C, the contact angle is approximately 0°. Because the maximum temperature of the experiment has reached the decomposition temperature of TiN film, therefore, the contact angle of TiN film with ionic bond is 35.3°, slightly larger than tool steel. However, there are complex ionic bond compounds Ti3AlN and covalent bond compounds Si3N4 in Ti–Al–N and Ti–Si–N films, which significantly reduce the wettability of the film with molten aluminum. The contact angles are 78° and 71°, respectively. During the oxidation process, due to Ti–Al–N and Ti–Si–N films contain Al and Si elements, the phase and morphology did not change until 800 °C, this indicates that the effects of different chemical bonds caused by alloying elements on oxidation resistance and wetting resistance have a similar relationship.

Experimental Characterization of Tool Wear Morphology and Cutting Force Profile in Dry and Wet Turning of Titanium Metal Matrix Composites (Ti-MMCs)

Metal-matrix composites (MMCs) are made of non-metallic reinforcements in metal matrixes, which have excellent hardness, corrosion, and wear resistance. They are also lightweight and may pose a higher strength-to-weight ratio as compared to commercial titanium alloys. One of the MMCs with remarkable mechanical properties are titanium metal matrix composites (Ti-MMCs), which are considered a replacement for super-alloys in many industrial products and industries. Limited machining and machinability studies of Ti-MMCs were reported under different cutting and lubrication conditions. Tool wear morphology and life are among the main machinability attributes with limited attention. Therefore, this study presents the effects of cutting and lubrication conditions on wear morphology in carbide inserts when turning Ti-MMCs. To that end, maximum flank wear (VB) and cutting forces were recorded, and the wear morphologies within the initial period of the cut, as well as the worn condition, were studied under dry and wet conditions. Experimental results denoted that despite the lubrication mode used, abrasion, diffusion, and adhesion mechanisms were the main wear modes observed. Moreover, built-up layer (BUL) and built-up edge (BUE) were the main phenomena observed that increase the tendency of adhesion at higher cutting times.

Convolutional neural networks for global human settlements mapping from Sentinel-2 satellite imagery

Spatially consistent and up-to-date maps of human settlements are crucial for addressing policies related to urbanization and sustainability, especially in the era of an increasingly urbanized world. The availability of open and free Sentinel-2 data of the Copernicus Earth Observation program offers a new opportunity for wall-to-wall mapping of human settlements at a global scale. This paper presents a deep-learning-based framework for a fully automated extraction of built-up areas at a spatial resolution of 10 m from a global composite of Sentinel-2 imagery. A multi-neuro modeling methodology building on a simple Convolution Neural Networks architecture for pixel-wise image classification of built-up areas is developed. The core features of the proposed model are the image patch of size 5 × 5 pixels adequate for describing built-up areas from Sentinel-2 imagery and the lightweight topology with a total number of 1,448,578 trainable parameters and 4 2D convolutional layers and 2 flattened layers. The deployment of the model on the global Sentinel-2 image composite provides the most detailed and complete map reporting about built-up areas for reference year 2018. The validation of the results with an independent reference dataset of building footprints covering 277 sites across the world establishes the reliability of the built-up layer produced by the proposed framework and the model robustness. The results of this study contribute to cutting-edge research in the field of automated built-up areas mapping from remote sensing data and establish a new reference layer for the analysis of the spatial distribution of human settlements across the rural–urban continuum.

Dry Machining Performance of AA7075-T6 Alloy Using Uncoated Carbide and MT-CVD TiCN-Al2O3-Coated Carbide Inserts

The present study examines dry machining performance of AA7075 T6 alloy using uncoated and MT-CVD TiCN–Al2O3-coated carbide inserts. Machining performance is assessed with regard to tangential cutting force, tool tip temperature and depth of flank wear. The performance of coated tool is compared to that of uncoated insert. In addition, different modes of tool wear and chip morphology are studied in detail. It is experienced that coated tool causes lower tool tip temperature and lesser flank wear than untreated counterpart. Apart from abrasion, adhesion and built-up layer formation; attrition wear is distinctly visible in case of uncoated tool. On the contrary, in addition to common wear modes, coated tool also experiences diffusion wear.

Impact of BUE on surface ruggedness for machining of aluminium matrix composites (6061/fly ash)

ABSTRACT Nowadays, when the aluminium metal matrix is machined, the devices are prematurely decepted mainly by adhesive wear. The adhesive wear leads to deterioration of surface texture and changes the cutting tool signature. Change of tool signature leads to over power consumption, reduction in effective use of the cutting tool and increase of surface roughness. The surface roughness on the machined component and formation of lay is dependent on the machining parameters, tool signature and machining conditions. This paper demonstrates the effect of Built Up Edge (BUE and Built Up Edge (BUL) on the surface roughness of the composites of fly ash in aluminium using K10. The results achieved were compared with Al6061 aluminium and Al6061 fly ash composites for different cutting edge speeds and feeds at a constant deep cut. The results of the experiment established the significant impact of cutting edge speed and feed on the making of the built-up edge and coating creation that rises surface rugging. Investigation specifies that the cutting edge speed and feed has the uppermost influence on the built-up edge and built-up layer creation while machining such as Al6061 aluminium and Al6061 fly ash composite and hence variation in surface roughness.

MODELLING AND SIMULATION OF POTENTIAL FUTURE URBANIZATION SCENARIOS AND ITS EFFECT ON THE MICROCLIMATE OF LOWER SESSION ROAD, BAGUIO CITY

Abstract. This paper analyzed both the horizontal and vertical extent of air temperature variations as affected by vegetation leaf area density (LAD) and building area per height threshold. The current microclimate (Scenario 1) and two potential future urbanization scenarios in Lower Session Road, Baguio City were simulated with ENVI-met. The future scenarios include the removal of the Balete trees in the median strip (Scenario 2), and removal of some pine trees and addition of new buildings in the study site (Scenario 3). Remotely-sensed data were used in creating the primary model inputs including the initial built-up layer from PlanetScope green-based built-up index (VgNIR-BI), and digital elevation models (DEM) and normalized difference vegetation index (NDVI) maps derived from unmanned aerial system (UAS) for tree canopy mapping. The horizontal variations in air temperature were observed by selecting three subsites with different proximity to the adjusted variables, while vertical analysis was done by comparing the temperature values from the near-ground up to the 20m height range. Very minimal temperature change (0 °C to −0.01 °C) was observed between the current and simulated scenarios when average temperature of the whole site is obtained. However, temperature variations were better observed with per-subsite analysis as the effects of the adjusted variables are seen to be localized and restricted only to the surrounding thermal condition. Air temperature is highest within 12:00 to 13:00 hours for the three scenarios. In the current scenario, the right region of the study site is cooler in the morning, which gradually became warmer pre-noon up to late afternoon. Removal of Balete trees with Scenario 2 have increased the temperature in the near-ground elevation only, both in Subsites 1 (up to 0.1 °C) and 3 (up to 1.6 °C), attributed to the loss of surface shadow and reduction in total LAD. In contrast, the removal of pine trees and addition of buildings impacted the air temperature across all subsites and across all atmospheric height ranges. Application of Scenario 3 to Subsite 3 which is close to the adjusted variables, gave the highest near-ground air temperature rise across the study site with a mean value of 1.4 °C and a maximum value of 1.9 °C. The ENVI-met model of the current scenario generated high accuracy (R2 = 0.59 to 0.99) which implies that the simulation outputs are reliable for this study.

Results of the experimental bits bench test, equipped with the compound built-up layers

The article shows the results of performance laboratory studies of compound built-up layers, as well as benches of the pilot tests of the drilling bit rolling cutters, equipped on the bit gage surface of the compound built-up layer; the hardening layers were located along the gage teeth contour. The cast tungsten carbide building-up welding on experimental bits was carried out using a gas-flame method. The induction method of building-up welding was implemented on the rolling cutters of the serial bits. The article shows the results of comparative indicators of serial and experimental bits when their processing on the bench. It was found that experimental bits were more efficient than the serial ones. The estimation of the performance laboratory tests results was confirmed by tests on the bench under pilot conditions of the rolling cutter bits drilling, equipped on the bit gage surface by the compound built-up layer.

Effect of increase of chrome and carbon content in the cored wire of Fe-C-Si-Mn-Cr-Ni-Mo-V system on physical and mechanical properties of built-up metal

Building-up of a layer, having high hardness, abrasive and shock-abrasive wear resistance on worn surfaces of mining equipment is the most perspective direction of their repair and restoration. For these purposes special building-up cored wires are used, development and production of which is made in both Russia and abroad. The aim of the research was to study the effect of chrome and carbon content in the blend of a new Fe-C-Si-Mn-Cr-Ni-Mo-V system cored wire on microstructure, wear and hardness of built-up metal. As a filler (blend) powdered materials were used: iron ПЖВ 1, ferrosilicon ФС 75, high-carbon ferrochrome ФХ 900 А , carbonaceous ferromanganese ФМн 78( А ), nickel ПНК -1 Л 5, ferromolybdenum ФМо 60, ferrovanadium ФВ 50 У 0,6, cobalt ПК -1 У , tungsten ПВН . Samples of the wire were made at a laboratory facility by multiple drawing through draw plate. The building-up by the manufactured wire was made in three layers under flux АН -26 С at a welding machine ASAW-1250 with the following parameters: I = 500 А , U = 29 V, V weld = 15 m/h. Results of the study of chemical composition, hardness and wear resistance of the built-up layers presented. A dependence of built-up layer hardness and its wear resistance on mass share of elements comprising the composition of the studied cored wires. It was shown, that the increase of hardness and decrease of wear speed takes place due to forming of martensitic structure of the built-up metal and due to increase of volume share of carbide phase of chrome when increasing chrome content from 1.8 until 5.2%, and carbon from 0.20 until 0.28%.

Experimental study on the effects of cold chamber die casting parameters on high-speed drilling machinability of casted AZ91 alloy

Abstract In this study, the effects of the cold chamber die casting parameters on high-speed drilling machinability of AZ91 Magnesium alloys were experimentally investigated. The influence of different casting parameters (casting temperature, molding pressure, and gate speed) on microstructure, mechanical properties and machinability characteristics (thrust force, tool wear, built-up edge, built-up layer formation, surface topography, chip morphology, and burr formation) were examined. The experimental results showed that the grain size of the conventional casting sample was around 50 microns, while in other cold chamber die casting tests, it varied depending on temperature, pressure, and gate speed. It was observed that the tensile strength values ​​of the samples produced with 1000 bar mold pressure were higher than those of other samples. In the formation of thrust force, the feed rate is more effective than the cutting speed. The least tool wear occurred in the drilling of the As-cast sample, while the highest tool wear occurred in the drilling of the sample which was produced with low pressure and low gate speed combination. As a result of the drilling tests, depending on casting and cutting parameters, three different types of chips were formed: fan, spiral cone, and long ribbon type. Furthermore, uniform and transient burrs in different sizes were observed.

Study on the protective effect of built-up layer in dry cutting of stainless steel SUS304

This work presents a systematic and comprehensive investigation of the protective effect of built-up layer (BUL) in dry cutting of stainless steel SUS304. A detailed examination of BUL and built-up edge (BUE) formation conditions, their formation mechanisms, and their protective effect was carried out at different cutting speeds (5–140 m/min), and different feed rates (0.02–0.1 mm/rev). The uncoated cemented carbide tool was used as a cutting tool. The dimensions of BUL/BUE and tool wear were measured by scanning electron microscope (SEM) and laser confocal microscopy (LCM). The protective effect of BUL/BUE was characterized using flank wear progression, as well as crater wear progression, cutting force analysis, and surface roughness analysis. As a result, it was found that BUE forms around the cutting edge at low cutting speeds (5–20 m/min), and BUL, which resembles a water drop, forms on the tool rake face at cutting speeds equal to or above 40 m/min. And a thin layer of flank built-up (FBU) can form on the tool flank face as the cutting speed increases from 40 m/min to 140 m/min. The BUL/BUE formation mechanism was also confirmed. It was revealed that BUL can be considered as a protective layer, which can not only prevent the tool rake face from wear but also decrease the tool flank wear, but BUE can only prevent the crater wear; and to a certain extent, the thin layer of FBU can also work as a protecting layer on the worn tool flank face in dry cutting of SUS304. It was also revealed that the height of BUL plays a very important role in its protective effect. Meanwhile, it was found that BUL and the thin layer of FBU have no or few influences on the amplitude variation of cutting forces and on the surface roughness. These results indicated that BUL can be used to realize the self-protective tool (SPT) in cutting of difficult-to-cut material such as SUS034. In addition, the research also proved that it is necessary to take the influences of BUL, BUE, and FBU formations on tool wear into account in the tool wear model in order to achieve high-precision prediction.

Evaluation of surface roughness and optimization of cutting parameters in turning of AA2024 alloy under different cooling-lubrication conditions using RSM method

In the present study, the effect of reduction of cutting fluid consumption on the surface quality and tool wear was studied. Mathematical models were developed to predict the surface roughness using response surface methodology (RSM). Analysis of variance (ANOVA) was used to investigate the significance of the developed regression models. The results showed that the coefficient of determination values (R2) for the developed models was 97.46% for dry, 89.32% for flood mode (FM), and 99.44% for MQL, showing the high accuracy of fitted models. Also, under the minimum quantity lubrication (MQL) condition, the surface roughness improved by 23%–44% and 19%–41% compared with dry and FM, respectively, and the SEM images of machined surface proved the statement. The prepared SEM images of tool rake face also showed a considerable decrease in adhesion wear. Built-up edge and built-up layer were the two main products of the adhesion wear, and energy-dispersive X-ray spectroscopy (EDX) analysis of specific points on the tool faces helped to discover the chemical compositions of adhered materials. By changing dry and FM to MQL mode, dominant mechanism of tool wear in machining aluminum alloy was significantly decreased. Breakage wear that led to early failure of cutting edge was also controlled by MQL technique.

Accuracy assessment of Global Human Settlement Layer (GHSL) built-up products over China.

Building a density map over large areas could provide essential information of land development intensity and settlement condition. It is crucial for supporting studies and planning of human settlement environment. The Global Human Settlement Layer (GHSL) is a comprehensive data set of mapping human settlement at a global scale, which was produced by the Joint Research Centre (JRC), European Commission. The built-up density is an important layer of GHSL data set. Currently, the validation of the GHSL built-up area products was preliminarily conducted over the United States and European countries. However, as a typical East Asian region, China is quite different from the United States, Europe, and other regions in terms of building forms and urban layouts. Therefore, it is necessary to perform an accuracy assessment of GHSL data set in Asian countries like China. With individual building footprint data of 20 typical cities in China, this paper presents our effort to validate the GHSL built-up area products. The aggregation mean and neighborhood search based algorithms are adopted for matching building footprint data and the GHSL products, through the regression analysis at per-pixel level, the building density map in raster format are generated as validation data. The accuracy index of GHSL built-up area was calculated for the study areas, and the validation methods were explored for GHSL built-up products at large scale. The results show that the built-up layer aggregated by the building footprint have the highest correlation with the coarse resolution GHSL built-up products, but GHSL tends to underestimate the building density of low-density areas and overestimate the areas with high density. This study suggests that GHSL built-up area products in 20 representative Chinese cities of China could provide quantitative information about built-up areas, but the product accuracy still need to be improved in the regions with heterogeneous formations of human settlements like China. There is a big picture of mapping high accuracy built-up density of China with the training data set acquired by the study.

Development of Technology of Robotized Laser Welding of Thin Wall Products from Heat-Resistant Alloys

Results of the developed industrial technology of restoration of a surface corrosion-resistant staly are presented by method of laser building up. The comparative analysis of a microstructure of the built-up wearproof layer, an alloyage zone with material of a basis and diffusive zone at the different technological modes of building up is given. Influence of morphology of particles of additive powder on parametrical characteristics of the roller received by laser gas powder building up is investigated. The optimum modes of building up on a substrate from steel 12Cr18Ni10Ti are set. Tests for firmness against intercrystalline corrosion of the built-up powder compositions are executed by the AM method. Metalgraphic assessment of corrosion resistance is presented.

Monitoring the land consumption rate of urban growth from the Urban Footprint of Mexico, an online national cartographic platform

The spatial monitoring of the urban expansion and related population growth is useful for urban planning assessment of cities and megacities in the global South. Although market driven public programs for peri-urban low-income housing have retained much attention over the past twenty-five years in Mexico, a spatially explicit database of the consequent urban footprint together with the population census information has not been available online to the public. In this research, we build a geoscientific data collection consisting of: 
 
 A built-up layer in 2000 and 2010 for the 10 major metropolitan areas of the Mexico Central Altiplano Region;
 A built-up layer in 2000 for the remaining 14 most prominent cities of the Mexican Urban System. 
 A land consumption index at county (“Municipio”) level in the Mexico Central Altiplano Region. 
 
 The Urban Footprint of Mexico is the first online national cartography incorporating built-up and demographic expansion.

On the turning of electron beam melted gamma-TiAl with coated and uncoated tools: A machinability analysis

Abstract Electron beam melting (EBM) is one of the promising technologies with the capability of producing complex near-net shapes from difficult to process materials such as titanium alloys. However, the parts produced from the EBM process suffer from the poor surface quality and machining is required to finish the EBM parts to achieve the necessary surface quality. Unlike the reported studies in the literature, the current study employs both uncoated, and PVD multi-coated (TiAlN/Al2O3/ZrCN) carbide inserts for the finishing of the electron beam melted γ-TiAl (Ti-48Al-2Cr-2Nb) and compares the machinability performance to identify the suitable type of the tool and the corresponding machining conditions. The obtained results indicate that the performance of the uncoated inserts is far superior as compared to the coated inserts in terms of producing lower tool wear and cutting forces, improved surface finish and morphology, and less subsurface microstructural and hardness alterations. The poor performance of the coated inserts is due to the high-temperature accumulation at the tool-workpiece interface due to the thermal shielding effect of the coatings, leading to severe built-up layer formation resulting in cascading effect of higher cutting forces, tool wear and oxidation, and poor workpiece surface integrity.

Processing of T6 heat-treated Al-12Si-0.6Mg alloy

ABSTRACTIn this study, ternary Al-12Si-0.6Mg material was manufactured by gravity die casting method in induction melting furnace. Microstructure images of alloy were taken on optical microscope after T6 heat treatment. Hardness, yield and tensile strength and breaking elongation of as-cast and heat-treated materials were measured by universal methods. CNC lathe was used for cutting tests and dynamometer was used to measure cutting force. Cutting tests were performed by using different cutting speeds-CS (450-500-550 m/min), feed rates-FR (0.05–0.15-0.25 mm/rev) and constant depth of cut-DOC (1.5 mm). Uncoated (A), CVD-TiCN + TiN (B) and PVD-TiAlN+TiN (C) coated carbide inserts were selected as a cutting tool. In the microstructural observations, it was determined that the structure of the material made up of aluminum rich α, primary and eutectic silicon, δ (Al4FeSi2) and π (Al8Mg3FeSi6) phases. The heat treatment refined the phases in the structure of the alloy. In addition, it has been determined that it improves mechanical properties (hardness, yield and tensile strength) by spheroidizing silicon particles. As a result of the cutting tests, it was detected that the cutting force (CF) reduced with T6 heat treatment at all CS and FR values. The CF, BUE (Built up edge) and BUL (Built up layer) heightened with increasing FR, while it reduced with increasing CS on all cutting tools. CF, BUE and BUL were formed at least in tools A, B and C, respectively. While continuous chip formation was detected in the as-cast part, brittle chip formation was observed in the heat-treated part due to the reduction in breaking elongation of the material.

Effect of Zinc Content and Cutting Tool Coating on the Machinability of the Al-(5–35) Zn Alloys

In this study, Al-5Zn, Al-15Zn, Al-25Zn and Al-35Zn alloys containing 5, 15, 25 and 35 wt% Zn, respectively were produced by permanent mold casting. Their microstructures and mechanical properties were investigated using metallography and universal hardness and tensile tests. Cutting tests of the alloys produced were carried out in a vertical machining center. During the tests, the cutting forces were continuously measured and saved by a software. The roughness of the machined surfaces of the alloy samples was measured accordance with the standard of ISO 4287. It was observed that Al-(5–15)Zn alloys exhibit single phase (aluminum rich α) microstructure while Al-(25–35)Zn alloys exhibit two-phase microstructure consisting of α and zinc rich η. As the zinc content increased the hardness and tensile strength of the alloys increased, but their elongation to fracture decreased. Cutting force, surface roughness, formation of built-up edge (BUE) and built-up layer (BUL), and the size of the chip occurring in the machining of the alloys decreased with increasing zinc content. The machining of the Al-(5-35)Zn alloys with uncoated WC tools results in both lower cutting forces and better surface quality compared to titanium-aluminum-nitride (TiAlN) coated tools. The changes in the cutting properties of the tested alloys with the increasing zinc content were discussed in the based on changes in structural and mechanical properties.

Experimental studying of the crack resistance for the CuAl9Mn2 alloy during growing of samples by the method of laser powder surfacing

The paper presents the results of experimental studies of crack resistance at the fusion boundary of the base material and the built-up layer in cylindrical specimens made of CuAl9Mn2 alloy using additive technology of powder laser surfacing. The aim of the study is to analyze possible changes in the mechanical properties of the base material at the fusion boundary under the action of high temperatures. On the basis of the experimental data it is obtained that the thermal action during laser powder surfacing has not a great impact on the crack resistance of both the base material and the built-up metal.

Investigating the influences of coatings on the built-up layer formation during cutting of Ti-6Al-4V

Investigating the influences of coatings on the built-up layer formation during cutting of Ti-6Al-4V