AISI D2 Research Articles

Effect of Ti interlayer on mechanical properties of TiZrN coatings on D2 steel

The objective of this study was to investigate the effect of Ti interlayer on the stress relief and mechanical properties of TiZrN coatings with thickness up to 3 μm. TiZrN coatings with 250-nm Ti interlayer (TiZrN/Ti) were deposited on AISI D2 steel substrate using unbalanced magnetron sputtering. In addition to TiZrN/Ti specimens, two more sets of specimens were prepared for comparison, namely, TiN and TiZrN monolayer coatings. The results showed that Ti interlayer can enhance the (111) preferred orientation of the thinner TiZrN coatings (≤1 μm); however, the preferred orientations of the thicker coatings (>1 μm) showed weak dependence on the Ti interlayer. The stresses in the TiZrN top layer, Ti interlayer and steel substrate were respectively measured using cos2αsin2ψ X-ray diffraction method. The results indicated that the stress in the top TiZrN layer was relieved by both Ti interlayer and the steel substrate for most of the TiZrN/Ti specimens, except for the specimen with 0.53 μm TiZrN, where the stress in the top TiZrN layer was mainly relieved by Ti interlayer. The stress relief reached a maximum in sample with 1.46 μm TiZrN. Then, the stress in TiZrN increased with the film thickness up to 3 μm, where the stress relief was mainly by the steel substrate. The results of scratch test showed that Ti interlayer could increase the adhesive strength. The wear resistance cannot be evaluated by individually considering residual stress or coating thickness. Instead, the elastic stored energy (Gs) combining the residual stress and coating thickness is a better index for evaluating the wear resistance of hard coatings. Adding a Ti interlayer may increase the wear resistance for coatings ≤1 μm; however, the wear resistance may decrease for thicker TiZrN coatings (>1.5 μm) due to the increase of Gs which decreases the capacity in absorbing the external input energy.

Laser Polishing of Cold Work Steel AISI D2 for Dry Metal Forming Tools: Surface Homogenization, Refinement and Preparation for Self-Assembled Monolayers

Liquid lubrication guarantees high precision and surface quality of workpieces in industrial forming processes. In the case of aluminum cold extrusion, wear and cold welding due to direct contact of tool and workpiece are usually prevented by the extensive use of lubricants. Since the use of lubricants is economically and ecologically unfavorable, surface treatments of tools by, e.g. laser polishing and/or coatings are in the focus of current investigations to substitute these lubricants and establish so called “dry metal forming” processes. The material AISI D2, a ledeburitic 12% chromium steel which is known to have a significant amount of chromium carbide precipitations, is widely used in cold extrusion for forming tools. The large fraction of chromium carbide precipitations, however, hinder the formation of a dense self-assembled monolayer (SAM) that is necessary to avoid direct contact of reactive aluminum with surface oxides of the tool. Therefore, a homogeneous distribution of the chemical elements with a smaller fraction or no chromium carbides in the steel matrix, particularly in the tool surface, is aimed for. Using laser polishing, the surface layer is molten by continuous or pulsed laser radiation. Within the melt pool, the elementary distribution is homogenized as a result of thermal convection and diffusion processes, as well as a smoothed surface and a grain refinement are achieved. Consequently, the effects of the surface treatment by laser polishing on the area coverage of self-assembled monolayers are investigated. Thus, a combined surface treatment by laser polishing and functionalization with a dense self-assembled monolayer shall reduce overall adhesive wear. For this investigation, several specimens of conventional manufactured and powder metallurgical molten AISI D2 are laser polished using continuous or pulsed laser radiation or a combination of both. The resulting surfaces are investigated by microscopy and spectroscopic techniques to analyze the surface topography and the elemental distribution near to the surface. These results are compared to those of conventionally hand-polished specimens. Furthermore, the influence of the element homogenization and grain refinement on the area coverage of self-assembled monolayers is explored. First results show that laser polishing of AISI D2 is suitable to achieve a reduction of grain size and a more homogeneous distribution of chromium carbides within the surface layer.

Investigation of Friction Conditions in Dry Metal Forming of Aluminum by Extended Conical Tube-Upsetting Tests

In cold forming of aluminum, various lubricants and coatings are typically used to reduce friction and wear, resulting in higher workpiece surface quality. The preparation of the workpiece surfaces and the cleaning of the products after the forming step generate a significant amount of environmentally hazardous residues. Therefore, current research focuses on the realization of dry metal forming processes. Instead of lubricants, modified tool surfaces can also optimize tribological conditions in the interaction zone of forming tool and workpiece. The applicability of these surfaces needs further examination before usage within an industrial manufacturing process. In this paper, different surface modifications are examined by using a conical tube-upsetting test setup that is based on the concept of the well-known ring-compression test. The conical tool surface homogenizes the relative displacement between tool and workpiece and suppresses the appearance of a neutral point. Conical tools from AISI H11 / DIN 1.2343 and AISI D2+ / DIN 1.2379+ are laser polished and functionalized with self-assembled monolayers. Friction conditions resulting from different surface modifications are analyzed and evaluated by the use of nomograms. Moreover, the applicability of different friction laws for dry metal forming of aluminum is investigated.

Effect of Tool Wear on Machining GFRP and AISI D2 Steel Using Alumina Based Ceramic Cutting Tools

The alumina based ceramic cutting tools are used to machine glass fibre reinforced plastic (GFRP) composite material and AISI D2 steel. The machining studies were conducted using Ti[C,N] mixed alumina based ceramic cutting tool (CC650) and SiC whisker reinforced alumina based ceramic cutting tool (CC670). Machining process was performed at different cutting speeds at constant feed rate and depth of cut and the flank wear of the cutting tools were measured. From the machining studies, the wear behaviour of the cutting tool are studied and compared with reference to the work material. Very smooth wear land was observed while machining GFRP composite whereas, ridges and groves were observed while machining steel using alumina based ceramic cutting tools. The hard metal chips produced during machining has induced to undergo the severe in changes on machining D2 steel. Based on the flank wear, tool face fibre / matrix chip has prone to maximum wear of 0.4mm compared to machining a metal. On machining AISI D2 steel the machining has reduced one fold (1:2) than the GFRP composite material. In summary, Ti[C,N] mixed alumina cutting tool performance better on machining AISI D2 steel and SiC whisker reinforced alumina cutting tool for machining GFRP composite.

The influences of various mixed dielectric fluids on the performance electrical discharge machining of AISI D2 hardened steel

AbstractThis research mainly explores the influence of various mixed dielectric fluids on the performance of electrical discharge machining of AISI D2 hardened steels. In this investigation, four types of dielectric fluids such as pure kerosene, kerosene and chromium powder mixed, kerosene and Span‐20 surfactant and the combination of kerosene with chromium powder and Span‐20 surfactant were studied. The obtained results illustrated that the addition of chromium powder and Span‐20 surfactant in the dielectric fluid obtained high material removal rate, low electrode wear rate and good surface finish. The presence of chromium powder will stabilize the gap distance between electrodes which promotes the occurrence of multiple discharges in one input pulse and particle agglomeration is reduced after Span‐20 surfactant molecules cover the surface of debris and carbon dregs in kerosene solution. Combination of kerosene with chromium and Span‐20 surfactant were found significant to improve the effects of carbon accumulation and drag discharge, and reduce unstable concentrated discharge.

The influence of Span-20 surfactant and micro-/nano-Chromium (Cr) Powder Mixed Electrical Discharge Machining (PMEDM) on the surface characteristics of AISI D2 hardened steel

The application of powder mixed dielectric to improve the efficiency of electrical discharge machining (EDM) has been extensively studied. Therefore, PMEDM have attracted the attention of many researchers since last few decades. Improvement in EDM process has resulted in the use of span-20 surfactant and Cr powder mixed in dielectric fluid, which results in increasing machiniability, better surface quality and faster machining time. However, the study of powder suspension size of surface charateristics in EDM field is still limited. This paper presents the improvement of micro-/nano- Cr powder size on the surface characteristics of the AISI D2 hardened steels in PMEDM. It has found that the reacst layer in PMEDM improved by as high as 41-53 % compared to conventional EDM. Also notably, the combination of added Cr powder and span-20 surfactant reduced the recast layer thickness significantly especially in nano-Cr size. This improvement was great potential adding nano-size Cr powder to dielectric for machining performance.

Machining performance optimization during plasma arc cutting of AISI D2 steel: application of FIS, nonlinear regression and JAYA optimization algorithm

The work focuses on assessing the optimal machining conditions which could simultaneously satisfy multiple process performance indices during machining of AISI D2 steel. The main characteristic indices that have been considered here for evaluating plasma arc machining are surface roughness and material removal rate; the corresponding machining parameters are cutting speed, gas pressure and torch height. The study proposes an integrated optimization module combining fuzzy inference system, nonlinear regression and JAYA algorithm towards optimizing correlated multi-response features during machining of AISI D2 steel. Optimum value of machining parameters found as cutting speed of 4000 m/min, gas pressure of 95 psi and torch height of 0.5 mm using aforementioned methodology. Application potential of the aforesaid integrated optimization route has been compared to that of teaching–learning based optimization (TLBO) algorithm and genetic algorithm. It has been concluded that JAYA algorithm possesses less convergence time and hence execution is faster as compared to TLBO and genetic algorithm.

A Utility based Approach towards the Multi Objective Optimization during Turning of AISI D3 Steel using Various Bio Degradable Cutting Fluids

A Utility based Approach towards the Multi Objective Optimization during Turning of AISI D3 Steel using Various Bio Degradable Cutting Fluids

Comparative study on machinability improvement in hard turning using coated and uncoated carbide inserts: part II modeling, multi-response optimization, tool life, and economic aspects

The present study focused on mathematical modeling, multi response optimization, tool life, and economical analysis in finish hard turning of AISI D2 steel ((55 ± 1) HRC) using CVD-coated carbide (TiN/TiCN/Al2O3) and uncoated carbide inserts under dry environmental conditions. Regression methodology and the grey relational approach were implemented for modeling and multi-response optimization, respectively. Comparative economic statistics were carried out for both inserts, and the adequacy of the correlation model was verified. The experimental and predicted values for all responses were very close to each other, implying the significance of the model and indicating that the correlation coefficients were close to unity. The optimal parametric combinations for Al2O3 coated carbide were d1–f1–v2 (depth of cut = 0.1 mm, feed = 0.04 mm/r and cutting speed = 108 m/min), and those for the uncoated tool were d1–(0.1 mm)–f1 (0.04 mm/r)–v1 (63 m/min). The observed tool life for the coated carbide insert was 15 times higher than that for the uncoated carbide insert, considering flank wear criteria of 0.3 mm. The chip volume after machining for the coated carbide insert was 26.14 times higher than that of the uncoated carbide insert and could be better utilized for higher material removal rate. Abrasion, diffusion, notching, chipping, and built-up edge have been observed to be the principal wear mechanisms for tool life estimation. Use of the coated carbide tool reduced machining costs by about 3.55 times compared to the use of the uncoated carbide insert, and provided economic benefits in hard turning.

Vibration prediction in drilling processes with HSS and carbide drill bit by means of artificial neural networks

Vibrations occur in the cutting tool during machining. These vibrations adversely affect cutting tool’s life span, the measurement accuracy of the workpiece and the surface quality. In order to minimize these effects, an experimental study is conducted and the vibrations generated during the process are measured. The effects of these vibrations on the cutting tool and material are investigated. Drilling tests (total of 1304 experiments) are performed experimentally and modeled with artificial neural networks (ANN). Firstly, the hole drilling operation is applied to C2080 (AISI D3) cold work tool steel workpiece with high-speed steel and carbide cutting tools at cutting speeds of 15, 20, 25 and 30 m/min and at feed rates of 0.06, 0.08, 0.1 and 0.12 mm/(rev) and the vibrations in the x, y and z axes are measured. An experimental setup for vibration measurement is prepared so that the technical equipment works in harmony with each other. Secondly, input and output parameters are determined by classifying the data obtained in the experimental work, then a new ANN model is developed, and the results are compared with the experimental data. The aim of the study is to ensure the simulation of the vibrations that may occur during hole drilling processes via a model. In this context, high-reliability ANN model has been developed with a 4 input (cutting speeds, feed rates, cutting tool type and time) and 3 output (x, y, and z vibration values).

Machining of AISI D2 Tool Steel with Multiple Hole Electrodes by EDM Process

In recent years, with the increasing of technology the demand for machining processes is increasing for the newly developed materials. The conventional machining processes are not adequate to meet the accuracy of the machining of these materials. The non-conventional machining processes of electrical discharge machining is one of the most efficient machining processes is being widely used to machining of high accuracy products of various industries. The optimum selection of process parameters is very important in machining processes as that of an electrical discharge machining as they determine surface quality and dimensional precision of the obtained parts, even though time consumption rate is higher for machining of large dimension features. In this work, D2 high carbon and chromium tool steel has been machined using electrical discharge machining with the multiple hole electrode technique. The D2 steel has several applications such as forming dies, extrusion dies and thread rolling. But the machining of this tool steel is very hard because of it shard alloyed elements of V, Cr and Mo which enhance its strength and wear properties. However, the machining is possible by using electrical discharge machining process and the present study implemented a new technique to reduce the machining time using a multiple hole copper electrode. In this technique, while machining with multiple holes electrode, fin like projections are obtained, which can be removed easily by chipping. Then the finishing is done by using solid electrode. The machining time is reduced to around 50% while using multiple hole electrode technique for electrical discharge machining.

A Kinetic Model for the Boriding Kinetics of AISI D2 Steel During the Diffusion Annealing Process

In this work, a diffusion model was proposed to estimate the boron activation energies for FeB and Fe2B layers during the pack-boriding of AISI D2 steel at temperatures of 1223, 1253 and 1273 K for a treatment time varying between 2 and 10 h. This model considers the effect of boride incubation times during the formation of the FeB and Fe2B phases. To study the influence of diffusion annealing process on the boriding kinetics of AISI D2 steel, the mass balance equations were modified in order to follow the evolution of boride layers as a function of annealing time for the specified boriding parameters. Finally, the kinetic model was validated by a comparison of the experimental thicknesses of boride layers with the predicted ones at a temperature of 1243 K for 2, 4 and 6 h. A simple equation was then obtained for estimating the total time necessary to get a single boride layer (Fe2B) that depends on the boriding parameters and on the thickness of each boride layer prior to the diffusion annealing process.

Comparative investigation towards machinability improvement in hard turning using coated and uncoated carbide inserts: part I experimental investigation

The investigation of low cost uncoated and coated carbide insert in the hard turning of hardened AISI D2 steel (≥ 55 HRC) will definitely open up a new arena as an economical alternative suitable to industrial machining sectors. Thus, this paper reports the comparative machinability assessment for the hard turning of AISI D2 steel ((55 ± 1) HRC) by coated and uncoated carbide insert in a dry environment. Micro hardness and abrasion tests were carried out to assess resistance capability against wear. The above test results confirmed the greater wear resistance ability of Al2O3 coated carbide insert over uncoated carbide. Based on the extensive investigation of comparative machinability, the coated carbide insert (TiN-TiCN-Al2O3) outperformed the uncoated carbide insert with regard to surface roughness, flank wear, chip-tool interface temperature, and chip morphology. Abrasion and diffusion were observed as the principal tool wear mechanisms in the investigated range. The uncoated carbide failed completely due to the severe chipping and quick dulling of the cutting edge, which led to its unsuitability for machining hardened steel.

Influence of tool path strategies on friction and wear behavior of high-speed ball-end-milled hardened AISI D2 steel

This paper aims at exploring how tool path strategies influence the friction and wear behavior of high-speed ball-end-milled hardened AISI D2 steel. High-speed hard milling (HSHM) operations were conducted on a 5-axis machining center with three different tool path strategies. Dry sliding friction and wear tests of test samples versus GCr15 rings were performed utilizing a block-on-ring tester. Results showed that friction and wear behavior were closely associated with tool paths. Though the same cutting parameters were used, there is a numerical evidence on the difference in surface integrity for different tool path conditions. Low friction coefficient was obtained for surfaces with microgroove orientation perpendicular to sliding direction. Inclination extent of grain boundary can act as a wear resistance indicator. The subsurface softening degree is the most evident factor by which tool paths influence wear behavior. It determines the way of carbide spalling and the severity of plastic deformation and then the main wear mechanisms. This study indicates that the friction and wear performance of ball-end-milled surfaces suffering from known friction loads can be improved by appropriate selection of tool path strategies.

A predictive model for characterizing hardness of D2 tool steel by eddy current method: A statistical optimization approach

ABSTRACTResponse surface modeling is a well-grounded method to identify empirical relationships between factors involved in engineering experiments. This paper presents a novel mathematical/statistical approach to design an optimal predictive model to evaluate hardness by eddy current method. A new approach has been presented to find an optimal frequency in eddy current testing which maximizes detectability and accuracy of the measured values. In order to determine the hardness values of AISI D2 tool steel during tempering, the eddy current tests were conducted by applying different values of operating frequency in the range 50–1000 Hz. Unknown heat treatment conditions estimated from eddy current tests creates a link that provides hardness estimation. The results showed that coupling the eddy current method to the proposed model acts as a high accurate hardness measuring system for the samples with unknown heat treatment conditions.

Effects of cutting speed on tool nose wear with ACE-MQL aerosol at optimum-temperature

This study is focused on evaluating newly developed chilled-emulsion Minimum Quantity Lubrication (MQL) method on machining hard-to-cut metals. Previous research work revealed that, aerosol at 15°C provides the optimal tool life and generates the least surface roughness when machining AISI P20 and D2 tool steels at a given cutting speed. In that context, the influence of varying cutting speeds with MQL aerosol at 15°C is further studied in this paper. Three cutting speeds were used as per the tool manufacturer’s recommendations. For the aforementioned cutting conditions, tool nose wear were measured and topologies of worn cutting edges were observed and compared. The experimental results revealed that tool wear rate and other forms of damages such as chipping and plastic deformation for different work material have contrasting responses. This indicates that MQL aerosol performance is notably sensitive to work material properties and its benefits as a cutting fluid should be further investigated over wider range of materials.

Control of tribofilm formation in dry machining of hardened AISI D2 steel by tuning the cutting speed

This study is focused on the investigation of nano-scale tribological effects formed during the machining of hardened material. Tribofilm formation was associated with the transfer of workpiece material to the cutting tool surface with further tribo-oxidation occurring through interaction with the environment. In addition to wear evaluation studies, a number of advanced surface analytical techniques were used to characterize surface phenomena, including X-ray photoelectron spectroscopy (XPS) and Auger Electron Spectroscopy (AES) (including AES imaging). This was combined with Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDX) studies. Wear performance of uncoated ceramic (mixed alumina and TiCN) tools was studied in detail at different constant cutting speeds (50; 80; 100 and 120 m/min) and tuned through two-step and three-step cutting speed adjustments (120–100 and 120–100–80 m/min) during hard dry turning of AISI D2 tool steel. The tuning of the cutting speed was performed in order to enhance the generation of favourable tribofilms and obtain an extended tool life. As a result of these tuned cutting approaches, tool life was increased by 36% at 120–100 m/min and improved 99% at 120–100–80 m/min when tested separately. Both the two-step and three step speed adjustment involved enhanced formation of beneficial tribofilms on the tool surface under a higher cutting speed, with a subsequent lower speed preventing the wearing out of these films and thus sustaining the improved tribological conditions. This research provides a novel strategy to enhancing the efficiency of machining processes which operate under extreme tribological conditions of dry machining of hardened tool steels.

Regression Modeling of EDM Process for AISI D2 Tool Steel with RSM

In this paper, Response Surface Method (RSM) is utilized to carry out an investigation of the impact of input parameters: electrode type (E.T.) [Gr, Cu and CuW], pulse duration of current (Ip), pulse duration on time (Ton), and pulse duration off time (Toff) on the surface finish in EDM operation. To approximate and concentrate the suggested second- order regression model is generally accepted for Surface Roughness Ra, a Central Composite Design (CCD) is utilized for evaluating the model constant coefficients of the input parameters on Surface Roughness (Ra). Examinations were performed on AISI D2 tool steel. The important coefficients are gotten by achieving successfully an Analysis of Variance (ANOVA) at the 5 % confidence interval. The outcomes discover that Surface Roughness (Ra) is much more impacted by E.T., Ton, Toff, Ip and little of their interactions action or influence. To predict the average Surface Roughness (Ra), a mathematical regression model was developed. Furthermore, for saving in time, the created model could be utilized for the choice of the high levels in the EDM procedure. The model adequacy was extremely agreeable as the constant Coefficient of Determination (R2) is observed to be 99.72% and adjusted R2-measurement (R2adj) 99.60%.

Minimizing the Adhesion Effects in Food Packages Forming by the Use of Advanced Coatings

The metal packaging industry used for food application has undergone drastic changes in the demands of its final consumers. The raw material for these packages, is a low carbon steel coated with a thin layer of tin (2,0 g/m2), also known as tinplate. The stamping process of these packages occurs at room temperature and is critically influenced by the tin transfer from the steel surface to the tool surface, mainly due to the tin softness. This problem is easily solved using lubrification but the purpose of this study will be the reduction or even absence of lubricants during the process in order to comply with costumers’ requirements. A successful way to minimize the consumption of lubricants is to use tools which are coated with PVD (Physical Vapour Deposition) advanced coatings deposited with unbalanced magnetron sputtering technique. Thin WC (Tungsten Carbide) and CrCN (Chromium Carbonitride) coatings were deposited using PVD on tool stamping steel – AISI D2. Block on ring tribological tests were performed on the coatings against tinplate counterface in order to investigate their wear performance, with particular emphasis on the material transfer (tin) phenomena during the sliding tests. The results allowed for selecting the best coating tested with a view to avoid the tin adhesion to the die.

Effects of cryogenic cooling on the surface integrity in hard turning of AISI D6 steel

Methods able to enhance surface integrity of machined components have been one of the emerging areas in manufacturing engineering, and a technique that has been providing satisfying results in the last years is cryogenic machining. Besides promoting surface integrity improvement, it is considered an alternative to the use of conventional cutting fluids, which is in accordance with the latest global trends for sustainable means of production. In this sense, replacing grinding operation, which uses large volumes of conventional cutting fluids, by hard turning assisted by liquid nitrogen, for example, could be a good choice. The aim of this work was to investigate the effects of cryogenic cooling on the surface integrity of quenched and tempered AISI D6 tool steel after turning operation. Dry and cryogenic turning trials with polycrystalline cubic boron nitride tools were performed and the results of surface integrity (surface roughness and topography, microhardness and residual stresses, as well as the modified microstructure of the deformed layer) were analyzed for comparison. The results showed that cryogenic cooling played an important role in modifying the workpiece surface integrity, providing low values of surface roughness (similar to those obtained in grinding operations), as well as higher values of surface microhardness and compressive residual stresses as compared to the dry condition.