D2 Tool Steel Research Articles

Micro-magnetic characterisation of ground AISI D2 tool steel using hysteresis loop technique

According to tooling industries, grinding is the most effective and economical machining for AISI D2 tool steel owing to its low thermal conductivity. The first objective is to investigate the effect of grinding environments on surface integrity of AISI D2 tool steel. Grinding performance like force ratio and grinding temperature was investigated under wet and dry environments. The second objective is to qualitatively assess the thermal damage of ground surface using non-destructive hysteresis loop (HL) technique. The result shows that higher force ratio and surface roughness were obtained under flood grinding. Maximum thermal damage in terms of drastic variation in microstructure and microhardness were observed under dry grinding owing to serious plastic deformation at higher grinding temperature. HL outcomes like lower average permeability, higher coercivity and remanence were obtained with higher thermal damage on ground surface. Finally, linear correction was obtained between HL outcomes and microhardness of ground samples.

On the Use of Microscale Abrasion Test for Determining the Particle Abrasivity

Abstract Particle abrasivity is an important concept for helping to select materials for pumps and for disc cutters in underground excavation, and specific ASTM standards are available for making these selections. However, for manufacturing processes in which abrasive action is their core, the particle size range is approximately a few micrometers. The evaluation of particle abrasivity using the microscale abrasion test matches this range of particles for this purpose, but relatively few investigations using this kind of method have been conducted. The aim of this investigation is to use the microscale abrasion test to evaluate the particle abrasivity, avoiding changes on the ball surface and on the particle size distribution. Samples of quenched AISI D2 tool steel were used for tests. The wear mode was dependent on the testing time. Alumina (Al2O3) particles presented a lower abrasiveness when compared to boron carbide (B4C) ones, confirmed by the higher wear coefficient found in the latter after reaching the steady-state regime. This behavior was evidenced by the number of active particles in the contact, which showed that there were a larger number of B4C particles than Al2O3 during the contact at all sliding distances. The particle abrasivity is discussed in terms of significant characteristics of slurries: particle shape, particle size distribution, hardness-to-elastic modulus ratio, zeta potential, and density. As the controlling of those characteristics seems to be very important, particle abrasivity is a concept that needs to be improved besides the test system used for that purpose.

Micro-magnetic characterisation of ground AISI D2 tool steel using hysteresis loop technique

According to tooling industries, grinding is the most effective and economical machining for AISI D2 tool steel owing to its low thermal conductivity. The first objective is to investigate the effect of grinding environments on surface integrity of AISI D2 tool steel. Grinding performance like force ratio and grinding temperature was investigated under wet and dry environments. The second objective is to qualitatively assess the thermal damage of ground surface using non-destructive hysteresis loop (HL) technique. The result shows that higher force ratio and surface roughness were obtained under flood grinding. Maximum thermal damage in terms of drastic variation in microstructure and microhardness were observed under dry grinding owing to serious plastic deformation at higher grinding temperature. HL outcomes like lower average permeability, higher coercivity and remanence were obtained with higher thermal damage on ground surface. Finally, linear correction was obtained between HL outcomes and microhardness of ground samples.

Analysis on surface finish and chip morphology during dry turning process

In this paper the effect of input variables such as spindle rotation, feed rate and depth of cut on surface roughness and chip thickness which were taken as the output parameters were analysed during dry turning process. Single point carbide turning insert and AISI D2 tool steel were used as cutting tool and workpiece material respectively. 2D roughness profile and scanning electron microscope images were used to analyse surface roughness and chip thickness respectively. It is observed that surface roughness and chip thickness are affected mostly by feed rate. Minimum surface roughness of 0.242 μm and least chip thickness of 0.233 mm were achieved. A multiple linear regression model is proposed to estimate the influence of input variables on surface roughness and average chip thickness. The model predicts surface roughness and chip thickness with R2 = 77.5% and R2 = 78.1% respectively.

Examination and prediction of process parameters for Surface roughness and MRR in VMC-five axis machining of D3 steel by using RSM and MTLBO

VMC five-axis is modern machining method, used for milling operations that focus on rotary cutters to extract surplus material from a work piece. To achieve machining economics in VMC-5-axis machining, choice of optimum process variables is crucial. Surface roughness and material removal rate are significant response variables, and analyzing and optimizing both the responses combinedly is an important research area in milling. Current research is planned to analyze, model and predict the optimum milling parametric condition of VMC-5-axis machining of D3 tool steel to anticipate surface roughness and MRR simultaneously by applying response surface methodology and multi-objective teaching learning-based optimization (MTLBO). The experiments had been planned as per Box-Behnken design of response surface methodology. Statistical analysis of variance (ANOVA) is applied to determine the significances of milling conditions on milling performance characteristics. ANOVA results revels that milling processing conditions are more significant for MRR as compared to surface roughness. Modeling of responses is made by RSM. Contour plots are drawn from developed mathematical models for visualizing the direct and combined effects of milling conditions on both the responses. Multi-responses are solved by MTLBO technique. Predicted milling condition is verified by confirmatory test. The concluding remarks have been drawn from the study. From the present research work, it is found that milling responses are improved at predicted condition obtained by hybrid RSM and MTLBO approach.

Hard turning of AISI D6 tool steel under dry, wet and cryogenic conditions: An economic investigation aimed at achieving a sustainable machining approach

The aim of this study was to encourage cleaner production processes by investigating the economic feasibility of using LN2 as a cutting fluid in the turning of quenched and tempered AISI D6 tool steel using solid PCBN inserts. For this purpose, an LN2 supply system was developed to deliver liquid nitrogen to the tool rake and flank faces. In order to measure the LN2 mass flow rate, a system based on load cells was set up. Three different LN2 flow rates (79, 51 and 21 ​L/h) were investigated. For comparison, turning tests under dry and wet conditions using a mineral-based emulsion were also performed. Nose wear (VBC) was monitored and used as one of the input parameters for an economic analysis, which was performed based on a previous study. It was concluded that the LN2 delivery system and the method used for the LN2 flow rate measurement were effective in supplying liquid nitrogen to the cutting zone in a controlled way, and liquid nitrogen at the highest flow rates provided longer cutting tool life than dry and wet conditions. Furthermore, the use of an emulsion did not increase the cutting tool life in comparison with the dry condition and machining assisted by LN2 at the lowest flow rate presented no statistical difference as compared to the wet condition in terms of production cost. Thus, based on this case study, liquid nitrogen can be considered as a sustainable alternative to the use of mineral-based emulsions, without incurring economic losses.

Modelling and Optimizing Process Parameters of AISI D2 Tool Steel for WEDM automation

The AISI D2 tool steel are the material that for machining of heat treated AISI D2 tool steel, a highly developed method must be employed. Due to exceptional thermo-mechanical properties and superior wear resistance AISI D2 tool steel are finding widespread applications in a lot of manufacturing industries. WEDM is one of the highly developed and sophisticated methods for making of intricate shapes and convoluted details as required for dies and punches. For efficient machining, the need of optimization and appropriate choices of process parameters such as Material Removal Rate and Surface Roughness is utmost goal.

Particle Swarm Optimization and Machinability Aspects during Turning of Hardened D3 Steel

Metal cutting processes are associated with excessive forces, friction and heat generation due to continuous intensive contact between the active cutting tools and the work which degrades the machined surface quality. The hardened tool steel having excellent wear resistance property receives an extensive promotion, investigation and application in the die manufacturing industries. In this research, the machinability of hardened AISI D3 tool steel has been investigated using TiN-coated Al2[Formula: see text](C,N) ceramic tool inserts as per Taguchi’s [Formula: see text] orthogonal design of experiments is in horizontal turning under the dry condition. The experimental dataset was used for the regression model development of primary process outputs as well as mean cutting force using the response surface methodology (RSM) which was found to be significant. The parametric interaction effects on each process output were studied along with with chip morphology in detail. The cutting force as well as material removal rate was found to be significantly influenced by depth of cut, whereas machined surface quality was primarily dependent on tool feed rate. The wider with less prominent saw tooth chips got changed to narrower saw-tooth form with intensive shear bands at higher feed rates. Finally, an attempt has been made to develop an optimal parametric setting using particle swarm optimization technique to achieve minimum surface roughness and maximum material removal rate at less cutting force. The optimal parametric setting was high cutting speed (308[Formula: see text]m/min), high tool feed rate (0.08[Formula: see text]mm/rev) with medium depth of cut (0.6[Formula: see text]mm) to achieve each objective. This evolutionary particle swarm optimization technique was found to be highly accurate (within 8% error) as per validation experiment.

Quantification of the Dislocation Density, Size, and Volume Fraction of Precipitates in Deep Cryogenically Treated Martensitic Steels

Two groups of martensitic alloys were examined for changes induced by deep cryogenic treatment (DCT). The first group was a range of binary and ternary compositions with 0.6 wt % carbon, and the second group was a commercial AISI D2 tool steel. X-ray diffraction showed that DCT made two changes to the microstructure: retained austenite was transformed to martensite, and the dislocation density of the martensite was increased. This increase in dislocation density was consistent for all alloys, including those that did not undergo phase transformation during DCT. It is suggested that the increase in dislocation density may be caused by local differences in thermal expansion within the heterogeneous martensitic structure. Then, samples were tempered, and the cementite size distribution was examined using small angle neutron scattering (SANS) and atom probe tomography. First principles calculations confirmed that all magnetic scattering originated in cementite and not carbon clusters. Quantitative SANS analysis showed a measurable change in cementite size distribution for all alloys as a result of prior DCT. It is proposed that the increase in dislocation density that results from DCT modifies the cementite precipitation through enhanced diffusion rates and increased cementite nucleation sites.

Effects of Cooling Parameter and Cryogenic Treatment on Microstructure and Fracture Toughness of AISI D2 Tool Steel

The application of cryogenic treatments is gradually increasing in tool steels. In this sense, these heat treatments can modify the mechanical properties of high chromium alloy steels. However, the influence of the cooling parameter (during quenching) is often neglected. This investigation aims at evaluating the effects of cooling parameter and cryogenic treatment on microstructure and fracture toughness of AISI D2 tool steel. The cooling parameter (λ) was defined as the cooling time from 800 to 500 °C divided by 100. During quenching, different cooling parameters (λ1 = 2.8 and λ2 = 1.8) were employed, and the samples were tempered three times or, besides, cryogenically treated by a single tempering. Later, the samples were evaluated through phase analyses and their proportions, sizes, and distribution of carbides by optical and scanning electronic microscopy, hardness measurements, x-ray diffraction, and fracture toughness tests. For the λ2 cooling parameter followed by cryogenic treatment, the results presented an increase of 51% over the initial condition of secondary carbides. However, the higher hardness values were found in the λ1 cooling parameter followed by cryogenic treatment. In the fracture toughness evaluation, a reduction of 8% in KIC was observed for samples with cryogenic cycles compared to the samples without it.

Cryo-Treated Blanking Punch Life Improvement Analysis

Cryogenic treatment is a secondary process to traditional heat treatment used for improving the hardness and wear resistance of tool steels. Though the potential use of cryogenic treatment on AISI D2 tool steel under laboratory conditions has been well established by the researchers, it is essential to do the analysis to ensure its sustainable use for industrial application. Therefore, impact of cryogenic treatment on AISI D2 steel blanking punch was evaluated in terms of increase in production rate and its life. The cryogenically treated D2 tool steel punches were used and subjected to manufacture the control levers using blanking operations. The improved wear resistance of cryogenically treated punch resulted in increase in production and punch life more than 200%. Punch life was studied and correlated to increase in production & wear behavior of blanking punch. The AISI D2 steel samples were prepared and subjected to laboratory tests comprising of metallographic observations and hardness. It was found that laboratory tests were not enough to predict improvements in mechanical properties. The mechanism responsible for augmented wear resistance by cryogenic treatment was the conversion of retained austenite to martensite and precipitation of new secondary carbides.

IMPROVED REPRODUCIBILITY OF D2 TOOL STEEL AFTER CRYO-TREATING AT -78°C (DRY ICE)

The exposure of steel to very cold temperatures (cryogenics) as a means to improve properties of the metal has had a controversial history. This study employed several tests to determine differences between D2 tool steel cryo-treated in dry ice (-78°C) versus in liquid nitrogen (-196°C), as compared to control D2 steel (not cryo-treated). These tests showed no major changes between the control and the liquid nitrogen treated steel, but the dry ice (-78°C) treated steel showed narrower XRD peaks, more reproducible hardness measurements, less scatter in the corrosion weight loss, and lower corrosion currents in the cyclic polarization tests in saltwater. All these differences were measured even though there was no measurable difference in retained austenite. The authors hypothesize that the -78°C (dry ice) allowed internal stress reductions, while the -196°C (liquid nitrogen) was too cold to allow any transformations.

Precision Multi-Response Optimization of Performance Characteristics In Wire-Cut Electric Discharge Machining (Wedm) Process

In this paper, an effective two stage multi-response optimization technique (i.e. grey relational analysis coupled with Taguchi technique) has been applied to achieve a better performance characteristic in wire-cut electrical discharge machining (WEDM) process. A zinc coated brass wire of 0.25 mm diameter was used as tool electrode for machining a D2 tool steel specimen. Experiments were planned according to Taguchi’s L9 orthogonal array under different cutting parameters such as: pulse on time (TON), pulse off time (TOFF), peak current (IP) and wire feed rate (WF). The three quality characteristics (i.e. performance characteristics), namely cutting rate, kerf width and surface roughness have been simultaneously optimized in two different stages. It wasobserved that the cutting speed is increased by 24.60% compared to first stage/primary optimization process. From the analysis of variance (ANOVA), pulse-on time is found to be the most influencing cutting parameter having 74.91% contribution towards overall performance of the WEDM process. Finally,a confirmatory experiment has been carried out at optimum set of cutting parameters obtained from the precision optimization stage to identify the effectiveness of this proposed method. It was observed that the predicted values of the responses obtained from regression models were in good agreement with the experimental findings.

Influence of Intermediate Cryogenic Treatment on the Microstructural Transformation and Shift in Wear Mechanism in AISI D2 Steel

AISI D2 steels are an interesting family of tool steels that generally have applications in knife blades, shaper blades, and forging and punching dies due to its optimum toughness, lower wear rate, and relatively high hardness. The present research work aims to design a new heat treatment cycle consisting of single tempering followed by cryogenic treatment and soft tempering to improve the wear properties of these steels. Specimens of AISI D2 tool steel were subjected to three different heat treatment cycles: hardened and double tempered at 450 °C (HTT450), hardened and double tempered at 450 °C followed by cryotreatment and soft tempering at 250 °C (HTT450CT250), and hardened and single tempered at 450 °C followed by cryotreatment and soft tempering at 250 °C (HT450CT250). The microstructures of the samples were characterized for hardness, carbide density, impact energy, wear loss, wear surfaces, and residual stresses. The influence of these measured parameters on the wear behavior was determined using a pin-on-disc wear testing machine. The results confirmed that HT450CT250 is the optimized heat treatment cycle out of the three cycles studied, which showed enhanced wear resistance index, minimum compressive residual stresses, and optimum impact toughness due to increased volume fraction and finer distribution of carbides in the tempered martensite structure. It is further revealed that there is a change in morphology of carbides from globular to needle-shaped, resulting in wear transition, which is well corroborated by scanning electron microscopy studies and wear surface analysis.

CRUCIBLE REX M2

Abstract Crucible Rex M2 is a general-purpose high-speed tool steel that contains tungsten, molybdenum, chromium, and vanadium as principal alloying elements. It is suitable for a wide variety of cutting tools that require moderate feeds and speeds. For cold work applications, Rex M2 offers higher hardness and wear resistance than Type D2 tool steel. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on low and high temperature performance as well as forming, heat treating, machining, and surface treatment. Filing Code: TS-801. Producer or source: Crucible Industries LLC.

Contribution in developing a rapid strategy in assessing hardened steel machining

The present work is a contribution to developing a strategy for rapid analysis of the behaviour of surface roughness and tool wear during machining hardened steel with carbide cemented cutting tools on conventional cutting machines. In agreement with dies and mould manufacturers in East Algeria, the strategy is based on the machining potential of the manufacturers, cutting tools manufacturer’s guidelines and recommendations from literature. The agreement suggested to focus on up and down shoulder finish milling of hardened AISI D3 tool steel using GC1030 insert on a conventional vertical milling machine. The strategy has been developed within five successive steps starting from the analyses of the performance of a machine tool to the definition of an experimental plan to respect. As expected, results show that down shoulder milling is the most suitable process rather than up shoulder milling which must be avoided whatever the hardening condition. In addition, the best performance of down shoulder milling is obtained when machining unhardened steel. In the as-received condition (31.6 HRc) when using down milling the cutting speed can be increased up to the maximum value of 113 m/min, however, the tool life obtained for this value is three times lower than that at Vc = 59 m/min. In 49 HRc hardening condition, milling at Vc = 59 m/min resulted in the good surface finish but with a tool life 6.5 times lower than the tool life when milling in the as-received condition. Vibration measurements provide a time referential data on the evolution of surface roughness together with corresponding tool wear. A time referential data on the evolution of displacement together with the corresponding tool life has been proposed as useful information to meet the needs of dies and moulds manufacturers when milling hardened steels.

Modelling of material removal rate and tool wear rate in EDM based on a fraction of energy approach

ABSTRACT To run any machine effectively and economically, the effect of different process variables on the performance must be known. An experimental investigation is costly, time-consuming as well as difficult for a complete understanding of the EDM process. Hence, several researchers have developed various models of the process using different approaches like mathematical modeling, finite element analysis, regression modeling, dimensional analysis, etc. based on certain assumptions and simplifications, which limit the accuracy of prediction. In this article, a novel modeling approach is presented to predict material removal rate (MRR) and tool wear rate (TWR) during machining of AISI D2 tool steel by the copper electrode using the full factorial design. The validation was carried out using Taguchi’s L9 orthogonal array-based confirmation experiments. The results showed that these models can be used for prediction of MRR and TWR at any set of process parameters for a given combination of workpiece and tool with good accuracy.

Effects of rapid heating and uniaxial loading on the phase transformation and mechanical properties of direct partial remelted butt joint of AISI D2 tool steel

Tool steels are widely used in various industries, such as automotive, shipbuilding, manufacturing, and marine, for rolling mills, blanking metals, and punching dies, given their distinctive hardness, resistance to abrasion, and deformation. However, joining tool steels using the conventional fusion welding process is difficult because of the formation of dendritic structures and hot cracking, which affect the strength of joining. Therefore, this study proposed the direct partial remelting process (DPRMP) for the butt joining of AISI D2 tool steel. Moreover, different uniaxial loads of 0, 0.5, 2.5, and 5 N were applied during the joining process to investigate the microstructural evolution and mechanical properties of DPRMP samples. Results showed that the ferrite phase in the base material was changed to the austenite phase with globular shape in the joined samples through DPRMP. In addition, increasing the uniaxial load from 0 N to 5 N reduced the average grain size, increased the shape factor, and caused joining defects, such as voids, to disappear. Furthermore, the tensile strength of the DPRMP samples improved by increasing uniaxial loading from 0 N to 5 N due to the effect of grain boundary diffusion and the decrease in eutectic carbide at the joint interface. The highest tensile strength was achieved in DPRMP-5, with a value of 652 MPa and a welding efficiency of 103%. Moreover, the average hardness value of the fusion zone improved in the DPRMP samples and increased to 400 HV wherein the as-received material presented a value of 226 HV.

Synthesis of cubic boron nitride diffused-D2 steel surface composite by thermo-chemical diffusion process to enhance the wear resistance

The diffusion of cubic boron nitride (c-BN) on the D2 tool steel surface was investigated using a thermo-chemical process in order to enhance the tribological properties of tool steel surfaces. The c-BN was diffused on the tool steel surface applying the thermochemical diffusion process using argon controlled furnace. The effect of temperature and soaking time on the diffusion process, micro-hardness, and wear resistance were the main parameters evaluated. The field-emission scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) was used to analyze the morphology and elemental composition of the as-synthesized c-BN-D2 surface composite. Here, the micro-hardness of manufactured coatings was investigated using a Vickers hardness tester. The wear resistance of surface composite was studied using a pin-on-disk apparatus. The morphological investigation revealed that c-BN was successfully diffused in the surface of tool steel in the form of white globular precipitates. The best surface hardness produced has a values of 1570 GPa. The diffused layer thickness varies between 50–90 μm and is very dense. It has mechanical interlocking properties suitable against delamination process and wear formation. The superior performances of novel c-BN-D2 tool steel surface composite permits to extend the machine tool life, especially when is applied on the single-point cutting tools.

A comparative study on coated carbide inserts performance in cryogenic end milling of AISI D2 tool steel

Cryogenic metal removal with the help of liquid nitrogen will be a clean substitute for our conventional flood cooling due to environmental regulations in the machining industries. The present work experiments the efficiency of TiN as well as TiAlN layered insert of carbide in the process of milling which takes place at the end in AISI D2 steel. The performance caused by cryogenic machining for the finishing on the surface and tear and wear of the tool are studied, the results are estimated with dry and existing flood coolant metal removing process at different cutting speeds. When estimated with TiN layered inserts, inserts of TiAlN shower maximized life of the tool and maximized finishing in the surface during metal removing process at several speeds behind their spindle, more than that they are environmentally clean metal removing process. We are going to discuss the significance of the cryogenic metal removal process which provides its importance for increased efficiency of machined components through its better penetration of lubrication in the tool and workpiece interface.