High Speed Steel Surface Research Articles

Design of AlCrSiN multilayers and nanocomposite coating for HSS cutting tools

In the present work, AlCrN coating and AlCrSiN multilayer and nanocomposite coating were designed and deposited on the surface of high speed steel (HSS) cutters. The microstructures of these coatings were investigated systematically by means of grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscope (XPS), electron probe X-ray microanalysis (EPMA), scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM), in association with mechanical property measurement and corresponding cutting test. The results showed that the AlCrN coating mainly composed of nanocrystalline fcc-CrN, hcp-AlN and fcc-(Cr,Al)N solid-solution. In addition to these nanocrystalline phases, a few amorphous Si3N4 phases were observed for the AlCrSiN multilayers and nanocomposite coating with a stronger {200} preferred orientation. The modulation period (6nm) of the AlCrSiN coating was much smaller than that of the AlCrN coating (18nm). The service life of the AlCrSiN coated tool increased approximately 40% longer in comparison with the AlCrN coated tool because of its more excellent mechanical properties (48GPa hardness, 1123MPa toughness, 52N LC2 adhesion strength and 0.25 average friction coefficient). During the cutting process, the wear mechanisms of coated tools at the early stage and mid-stage were abrasion wear and adhesion wear, respectively. And the worn loss of AlCrSiN coated tool was less than that of AlCrN coated tool.

Surface Modification of High-Speed Steel by Plasma Nitriding

The article investigates the changing in the structure and phase composition of the R6M5 high-speed steel surface layer after electrolytic-plasma nitriding. It is found that after electrolytic-plasma nitriding on the R6M5 steel surface, modified layer is formed, which consist from a diffusion layer. It was showed phase composition of difysion layer is changing depending on the nitriding. It is found that electrolytic-plasma nitriding lead to accelerated formation of the modified layer. It is determined that after electrolytic-plasma nitriding on the high-speed steel surface, modified layer is formed, consisting only of the diffusion layer.

Preparation and Characterization of Boron Carbon Nitride Films on High Speed Steel Surface

In this paper, we deposited BCN films on high speed steel (HSS) substrate by magnetron sputtering. The structure and composition of the films were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The tribological properties of the films was studied by ball-on-disc tribological test. Results show that BCN films have a certain antifriction effect, which is influenced by RF target power and substrate bias.

Structural-Phase Transformations in R6m5 Steel while Electrolytic-Plasma Processing

The article examines regularities of high-speed steel surface changes in the phase and structural states of during the electrolytic-plasma processing. It is determined that after modification by electrolytic-plasma influence on the surface of R6M5 high-speed steel formation of small pores, microdefects and fine inclusion. Surface modified layer consists of nitrogen austenite, nitrogen martensite and fine nitride particles.

Characteristic of TiN Film Prepared by Multi-Arc Ion Plating

Multi-arc ion plating technique was used to fabricate TiN film on the surface of high speed steel (HSS) to improve its wear resistance. The structure and morphology of TiN film were analyzed by XRD and SEM,and the bonding strength between the film and substrate was studied by the scratch tester. The results show that the thin film formed on the surface of the substrate consists of compact TiN. There are some white spots and black spots on the surface of the film. The bonding strength between the film and the substrate reaches 43 N/mm2, which correlates to formation of a pseudo diffusion layer. The tribological experimental results show that plating TiN film can greatly improve wear resistance of HSS.

Electrolyte Plasma Nitriding of High-Speed Steel

Developed a new method of electrolytic-plasma nitriding, which enable to carry out surface modification of high-speed steels and provide the high kinetic energy efficiency of diffusion saturation process. . Implementation of electrolytic-plasma nitriding of high-speed steel R6M5 in the optimal mode was determined, which leads to a significant increase in hardness and wear-resistance of the high-speed steel surface layer. It is experimentally established, that after nitriding of electrolytic-plasma heating on the surface of high-speed steel R6M5 formed the modified layer, which has high abrasive wear resistance as compared with the source material.

Surface Characterization of Electric Discharge Machined Surface of High Speed Steel

A comprehensive study of the Surface Characterization of Electric Discharge Machined surface of High Speed Steel work piece was investigated in this Project. EDM tests on High Speed Steel work piece were conducted on a Minor model Modern Machine Tools make Electric Discharge Machine with a transistorized pulse generator having a maximum output of 85 V and 20 A. The test conditions used were Copper electrode with negative polarity, kerosene as dielectric, side flushing, Pulse Current settings of 2, 5, 10, 15 and 20 A, Pulse on-times of 50, 200, 400, 800 and 1600 s with duty factor of 0.5, and 85V open voltage. The Electric Discharge Machined surface morphology was examined with a Metallurgical Microscope and Scanning Electron Microscope (SEM-Leo-440 model) with EDX analysis. It was observed that at low pulse current and low pulse on-time, the craters were shallow and the density of global appendages and pockmarks were low, whereas at higher pulse current and pulse on time, the craters were deeper and global appendages were most evident. These global appendages were molten metals, which were expelled randomly during the discharge and later solidified on the work piece surfaces. It is also observed that the EDM conditions have no effect on the microstructure of the bulk material work piece, and the damage caused by the EDM surface is limited to certain depth only. These changes will depend on the variation of pulse current and pulse on-time. The development of new, advanced engineering materials and the need for precise and flexible prototypes and low-volume component production have made Electric Discharge Machining an important manufacturing process to meet such a demand. Electric Discharge Machining (EDM) is a thermo electric process that erodes work piece material by a series of discrete electrical sparks between the work piece and an electrode flushed by or immersed in a dielectric fluid. Unlike traditional cutting and grinding processes, which rely on the force generated by a harder tool or abrasive material to remove the softer work material, the EDM process utilizes electrical sparks or thermal energy to erode the unwanted material and generate the desired shape. The hardness and strength of the difficult to machine work material are no longer the dominating factors that affected the tool wear and hinder the machining process. This makes the EDM process particularly suitable for machining hard, difficult to machine material. The EDM process has the ability to machine precise, complex and irregular shapes with a CNC control system. In addition, the cutting force in EDM process is small, which makes it ideal for fabricating parts with miniature features. Several theories were proposed by early investigators to account for the erosion mechanism of the EDM process. It has been accepted generally that the metal removal phenomenon is predominantly thermal in nature [1]. The best explanation of EDM phenomena has been established by extensive experimental studies [2, 3]. Three stages can be distinguished: 1. Ionization and arc formation, at a localized area between the electrodes, following the application of a voltage exceeding the breakdown voltage. 2. The occurrence of the main discharge as an electron avalanche striking the anode, with low electrical resistance in the discharge channel. The cathode is struck by ions and is heated less rapidly than the anode.

Property Study on High-Speed Steel Deposited TiN Coatings by Magnetron Sputter Ion Plating

TiN coatings were deposited by Magnetron Sputter Ion Plating (MSIP) on the surface of high-speed steel W18Cr4V.The microstructure,coating thickness, micro-hardness and wear resistance of surface modification sample were investigated by the D/MAX-ⅢB X-ray diffraction tester, the coating thickness tester, the HV-1000 micro-sclerometer,the LKDM－2000 friction and wear tester,the S-3000N scaning electron microscopy.The influence of sputtering time,N2 partial pressures and sputtering current on the microstructure,coating thickness, micro-hardness and wear resistance of TiN coatings were also analysed.The best synthesis performance sputtering coatings of technologic scheme was established.

Hardness profile improvement of plasma nitrided high speed steel by glow discharge heating

The hardness of a plasma nitrided high speed steel surface is extremely high at the surface because of the formation of nitrides and the diffusion layer. It decreases steeply to the value of the substrate. Such a brittle surface and steep change in hardness are not favourable for tool applications because of tool chipping. This paper investigated the improvement of such a hardness profile of plasma nitrided high speed steel using glow discharge heating as a post-nitriding diffusion treatment. High speed steel was plasma nitrided at 500°C under 667 Pa for 2 h in a gas mixture of nitrogen and hydrogen. A diffusion process was then conducted in the same chamber by changing the gas to hydrogen or argon. The plasma nitrided high speed steel was also diffusion treated by furnace heating. The microstructures and the hardness profiles of these two post-nitriding treated samples were compared. Diffusion treatment by glow discharge heating lessens the hardness gradient from steep to gentle more effectively than fur...

Effect of Laser Surface Melting on Structure and Properties of a High Speed Tool Steel

The purpose of this research paper is focused on the high speed steel surface layers improvement properties using HPDL laser. The paper present laser surface technologies, investigation of structure and properties of the high speed steel alloying with carbides using high power diode laser HPDL. Investigation indicate the influence of the alloying carbides on the structure and properties of the surface layer of investigated steel depending on the kind of alloying carbides and power implemented laser (HPDL). In the effect of laser alloying with powder of carbides occurs size reduction of microstructure as well as dispersion hardening through fused in but partially dissolved carbides and consolidation through enrichment of surface layer in alloying additions coming from dissolving carbides. Introduced particles of carbides and in part remain undissolved, creating conglomerates being a result of fusion of undissolved powder grains into molten metal base. The structural mechanism was determined of surface layers development, effect was studied of alloying parameters, gas protection method, and thickness of paste layer applied onto the steel surface on structure refinement and influence of these factors on the mechanical properties of surface layer, and especially on its hardness, abrasive wear resistance, and roughness. It has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the used ones.

Research on CBN Grinding Wheel Dressing with Ultrasonic Vibration Assistance and its Grinding Performance

The experiment of resin-bonded CBN wheel dressing using a diamond dresser assisted with longitudinal ultrasonic vibration along the direction of depth of cut was carried out and the dressing characteristics and grinding performance were discussed in the present paper. The influence of acoustic parameters on the topography of CBN wheel was studied to check the effectiveness of dressing for this method. The experimental results showed that the higher the ultrasonic frequency is, the better the wheel topography. The grinding on K9 optical glass and high speed steel has achieved higher G-ratio than that of traditionally mechanical dressed CBN grinding wheel. The ground surface of high speed steel is better than that of K9 optical glass. According to the interferometer images, it was concluded that the grinding of high speed steel was in ductile cutting regime, while removal of K9 optical glass was in brittle fracture regime.

Nitriding of high speed steel

Current practice when nitriding high speed steel (HSS) cutting tools is to avoid embrittlement of the cutting edge by limiting the depth of the diffusion zone. This is accomplished by reducing the nitriding time and temperature and eliminating any compound layer formation. However, in many applications there is an argument for generating a compound layer with beneficial tribological properties. In this investigation, results are presented of a metallographic, X-ray diffraction and X-ray photoelectron spectroscopy analysis of nitrided HSS surface layers generated using active screen plasma nitriding and reactive vapour deposition using cathodic arc. These results are discussed in the context HSS cutting tool performance when machining under built-up edge conditions.

Magnetic Field on Properties of Solid Lubricants Coating on High-Speed Steel Surface

The main factors that affect properties of solid lubricant coating on high-speed steel surface are the surface roughness and the weight of phosphate coating. The effect of magnetic field on high speed steel phosphate process is significant. It promotes the film and the different appearance and composition of the film. Because the ferric phosphate and dihydric phosphate in phosphate solution may be ordered arrangement by additional magnetic field, they can be deposited on metal surfaces quickly. That is to say that a certain intensity of the magnetic field can reduce the entropy of the phosphate processing system and speed up the formation of phosphate film. During phosphate treatment, the friction performance of high-speed steel coated with solid lubricant coating was significantly improved.

Development of a reversible machining method for fabrication of microstructures by using micro-EDM

A new micromachining method for the fabrication of micro-metal structures by using micro-reversible electrical discharge machining (EDM) was investigated. The reversible machining combines the micro-EDM deposition process with the selective removal process, which provides the ability of depositing or removing metal material using the same micro-EDM machining system. From the discharge mechanism of micro-EDM, the process conditions of micro-EDM deposition were analyzed firstly. Using the brass and steel materials as a tool electrode, the micro-cylinders with 200 μm in diameter and height-to-diameter ratio of more than 5 were deposited on a high-speed steel surface. Then the machining procedure was transformed easily from deposition to selective removal process by switching the process conditions. Different removal strategies including micro-EDM drilling and micro-EDM milling were used in the machining. Micro-holes with 80 μm in diameter are drilled successfully in the radial direction of the deposited micro-steel cylinder. Also, a brass square column with 70 μm in side length and 750 μm in height, and a micro-cylinder with 135 μm in diameter and 1445 μm in height are obtained by using micro-EDM milling. Finally, the characteristics of the deposited material were analyzed. The results show that the material components of a deposited micro-cylinder are almost the same as those of the tool electrode, and the metallurgical bonding has been formed on the interface. In addition, the Vickers-hardness of 454Hv of the steel deposited material is higher when compared to the hardness of 200Hv of the raw steel electrode.

Study of High Co Superhard High Speed Steel Surface

Cobalt- superhard high speed steel layer has been formed on the surface of low alloy steel 20Cr2V by tungsten-molybdenum-cobalt plasma surface alloying and following plasma carbonizing. After plasma surface alloying, a homogeneous and dense surface alloying layer was formed, thickness of which is 200μm. Composition, microstructure and properties of the alloying layer were investigated. Contents of W, Mo, Co, Cr, V and C in the surface layer reach 8%,5%, 6% ,4%,1.5% and 1.5% or so respectively. The concentrations of alloy elements basically meet the requirements of high cobalt type superhard high speed steel. Constituent phases of the surface layer were martensite, M7C3 ,M2C and Cr3C2 carbides and μ phase after quenching treatment. The advanced gradient superhard high speed steel possesses not only high surface hardness, high anti-temper softening ability but also enough toughness.

Micro-Forming Process and Microstructure of Deposit by Using Micro EDM Deposition in Air

Based on analysis of the mechanism of Electrical Discharge Machining (EDM) and the characteristics of deposition processing, the processing conditions of micro EDM Deposition (micro EDD) are determined. Micro EDD is a new EDM method taking air as machining medium, using narrow pulse width, long pulse interval, low discharge current and connecting the tool electrode with the anode of pulse generator. Using EDM shaping machine and brass, tungsten and steel as tool electrode respectively, micro cylinders are deposited on high-speed steel surface. And then the microstructure of deposit is analyzed detailedly. Results show that elements of the deposited material distribute uniformly, whose components depend on the tool electrode material. As the high cooling rate of the solidification process, the deposit grain size refines obviously, which leads to the hardness of tungsten or steel deposit increasing. Moreover, the Metallurgical bonding has occurred on the interface between deposit and high-speed steel base, whose thickness is about 5μm.

Tribological analysis of TiN and DLC coated contacts by 3D FEM modelling and stress simulation

Surface coatings, like titanium nitride (TiN) and diamond-like carbon (DLC) coatings, offer high wear resistance and good friction performance for a wide range of applications. With novel advanced techniques like modelling and simulation, the performance of these coatings can be predicted under a wide range of loading conditions. This provides valuable information for the coating design and for the use of coatings in different applications. A previously developed three-dimensional finite element method (FEM) model was used for calculating the first principal stress distribution in a scratch test contact as a spherical diamond tip is moving with increased load on DLC and TiN coated high speed steel surfaces containing no residual stresses. The used three-dimensional model is comprehensive in the sense that it considers elastic and plastic behaviour of the contacting surfaces. The first cracks to appear on the surface are angular cracks on the edge of the scratch groove. This corresponds to the region of high two directional tensile stresses occurring in FEM stress simulations at the edge of the scratch groove. The coating/substrate stiffness ratio influences considerably on the coating behaviour. The TiN coating that had higher Young's modulus compared to the substrate material experienced high tensile stresses when loaded by the diamond stylus. The DLC coating that had lower stiffness compared to substrate material experienced comparatively low tensile stresses. The DLC coatings had maximum tensile stresses in the range of 700–900 MPa. The TiN coatings had tensile stresses in the range 2200–3000 MPa. The coating thickness had only minor effect on the maximum tensile stress level for the 1 and 2 μm thick coatings. The location of the experimentally observed first crack in the surface corresponds to the location of maximum tensile stress concentrations in the stress simulations and the direction of the observed crack corresponds with the stress components in the calculated stress field. The role of residual stresses is discussed.

A Micro-Deposition Method by Using EDM

A new micro EDM method is described. First, the basic principles of micro EDD are analyzed and realized conditions are predicted. Then with an ordinary EDM shaping machine and electrode brass, steel and tungsten, a large number of experiments are carried out in air to obtain the effects of different processing parameters on micro EDD. A micro cylinder with 0.19mm in diameter and 7.35mm in height is formed on high-speed steel surface. By exchanging the polarities of electrode and workpiece the deposited material can be removed selectively, thus the reversible machining is realized. In the end, measurements show that the deposited material is compact and hardened, whose components depend on the tool electrode material although Zn in brass electrode is oxidized to ZnO.

Study of micromechanical properties of ion-beam mixed tungsten-on-steel layers

The relations linking structure, microhardness and adhesion were studied for ion-beam mixed tungsten layers deposited on the surface of high-speed steel. The 45nm thick W layer were mixed with 340keV Kr ions at temperatures ranging from RT up to 450°C. The increase of mixing temperature results in partial crystallization of the layers and the increase of the layer hardness. Substantial increase of layer adhesion has been observed in scratch tests for all mixed samples.

Effect of Heat Treatment on the Width of the Forbidden Band of Polyoxide Films Formed on the Surface of Tool Steel

The process of formation of polyoxide films on the surface of high-speed steel after high-temperature heating is studied. The relation between the modes of heat treatment of the tool steel and the width of the forbidden band of polyoxide films is obtained.