Wear Resistance Of High Speed Steel Research Articles

The formation of heterogeneous wear-resistant coatings by the additive technology method

The microstructure, hardness property and wear resistance coatings of WC, Ni-Cr and Fe powders deposited by laser cladding at varying processing parameters were investigated. The results of the present study revealed the prospects of multilayer cladding of R6M5 high-speed tool steel (analogy of M2 steel) onto low-alloy steel with the use of a laser beam. Controlling thermal cycles of laser cladding, it is possible to obtain a clad coating made of high-speed steel having the structure of high-alloy austenite martensite mixture with disperse inclusions of carbides up to 10 mm thick, i.e., it is actually possible to create bimetal structures. The wear resistance of the laser-clad self-fluxing PG-10N-01 (Ni-Cr-B-Si-C) alloy increases by a factor of 5 due to additional hardening by cast tungsten carbide with spherical particles. As a result, it becomes higher than the wear resistance of high-speed steel by more than a factor of 3.

Improving Properties of Tool Steels by Method of Dynamic Alloying

The influence of high-speed particle fluxes on changes in the structure and properties of materials has been widely studied currently. The effect exerted by particles moving at very high speeds can have both negative (in spacecrafts) and positive character (dynamic processing of tool steels). Therefore a task for studying an effect of high-speed particle flows on structure change in tool steels and improving their performance properties has been set in the paper. The study has used an explosive method for creation of a high-speed flow of SiC + Ni and Al2O3 particles. Samples after dynamic alloying have been subjected to diffusion nitriding. Microstructure of specimens made of X12M, R18, R6M5K5steel has been studied using optical and electron metallography. Wear resistance of the samples has been also tested on a friction machine. Theoretical and experimental results on a complex effect of high-speed microparticle flows and nitriding on a structure and properties of tool steels have been obtained during the research. It has been established that dynamic alloying by particles leads to formation of a specific structure in a composite material reinforced with channels. Central fiber (channel) zone with powder particles residues is surrounded by areas of amorphous state which is succeeded by a zone with a nanocrystalline fragmented cellular structure. Then we observe a zone with a microcrystalline structure that transits to a zone with crystalline structure which is characteristic for a matrix material of structural steel. The obtained data can expand and complement some ideas about mechanisms for dynamic loading of solids and condensed matter, plastic deformation, physical mechanics of structurally inhomogeneous media at different levels, a number of effects arising from collision and ultra-deep penetration of microparticles into metals. It has been shown that wear resistance of high-speed steel subjected to dynamic alloying in the quenched state is increased by 1.2 times in comparison with wear resistance of steel alloyed in the annealing state.

Research on the chance of increasing the wear resistance of high-speed steel Using chemical thermal treatment methods

The thermal borating methods from powder environment under heating conditions in a chamber furnace in order to determine their effect on the change in the structure and wear resistance properties of high-speed steel P6M5 was simulated by using Al2O3 to form neutral saturating environment. The simulated borating conditions included both saturation without heat treatment, and saturation with twin complex heat treatment in the form of quenching directly after borating, followed by tempering at a temperature of 200 °C for decrease tensions. The structures were researched in the directions of along and across the rolling, because this steel is prone to structural heterogeneity. The chamber with an operating temperature of 1250 ° C was used as heat treatment device. It is shown that thermal treatment modes, used in boronizing steels, slightly changes the structure of the core of P6M5 steel and does not lead to a significant decrease in its mechanical properties, which makes it possible to successfully combine boronization with the final heat treatment of high-speed steel. Regardless of the speed of cooling, the hardness of P6M5 steel is decreased insignificantly. It was noted that heat treatment in powdered saturating environment without a fuse or the use of a protective atmosphere does not lead to negative consequences for the structure and wear resistance properties.

High-Speed Steel Surface Modification by Electron-Beam Processing

The structure and microhardness of high-speed steels P6M5, P9 and P18 after electron-beam processing were investigated in the work. Electron-beam processing was carried out on the industrial accelerator ELV-4. It was established that electron-beam processing allows to obtain a modified layer on the surface of fast-cutting steels with thickness of 20 μm with high hardness, consisting of fragmented martensite with fine carbide particles. It was determined that after electron beam processing the microhardness of high-speed steels increased to 9.5 GPa. It has been experimentally established that the growth of hardness and wear resistance of high-speed steels after electron-beam processing is the result of the formation of more fragmented martensite and a decrease in the size of carbide particles.

Effects of Oxide Scale on the Corrosion and Mechanical Properties for a High Speed Steel and a Graphite Cast Iron

The mechanical properties and the oxidation characteristics of the high speed steel (HSS) for hot-rolling process, produced by centrifugal casting process, were investigated experimentally. Because of the complicated microstructure with tiny V-, Cr-, and W-based precipitations in the matrix, high hardness of the HSS samples was obtained. Moreover, high compressive strength and high compressive strain were detected, while low tensile properties were obtained. In spite of the high hardness of HSS, the wear resistance was a low level due to severe oxidation on the HSS surface and generated cracks, but the wear resistance of HSS was still better than conventional graphite cast iron. Although the corrosion occurred by the wear test, no clear microstructural change was detected. Wear and corrosion characteristics were examined at high temperatures and high humidity using an originally proposed testing machine. With this testing machine, failure characteristics of HSS were clarified, in which the HSS sample was worn away easily due to the brittle oxidation scale during the rolling process, leading to the rough HSS surface. Furthermore, the low tensile strength of HSS made an acceleration of the failure especially crack growth. Such rough surface has made reduction in the quality of the rolled materials.

Effect of Carbides on Wear Characterization of High-Alloy Steels under High-Stress Rolling–Sliding Condition

This article describes the wear characterizations of high-speed steel composed of vanadium carbide and high-chromium cast iron composed of chromium carbide. These metals were studied under rolling–sliding conditions with a sliding ratio of 10% using a self-made ring–ring wear testing machine. The fine microstructure of carbides and failure behaviors were analyzed by scanning electron microscopy and high-resolution electron microscopy. The results showed that carbide significantly affected the wear properties and failure behaviors of metals. The relative wear resistance of high-speed steel reinforced by vanadium carbides was twice that of high chromium cast iron composed of chromium carbides. Chromium carbide was characterized by a stacking fault substructure, and slips occurred in chromium carbide under high-stress contact, resulting in crack formation. Vanadium carbide was reinforced and pinned by large amounts of nanoparticles, which prevented its dislocation under high-stress rolling–sliding conditions, thereby effectively resisting crack initiation. Furthermore, the (200) lattice plane of vanadium carbide is coherent with the (111) lattice plane of austenite, preventing cracks from forming at the interface of the vanadium–carbide matrix. The morphology and hardness of vanadium carbide also contributed to the excellent wear property of high-speed steel.

Wear resistance of high-speed steel cutting tools

Wear resistance of high-speed steel cutting tools

Wear resistance of high-speed steels and cutting performance of tool related to structural factors

The dry, abrasive wear and cutting resistance of a high-speed steel has been investigated for both the cast and wrought states. The presence of a network of eutectic carbides in the cast material is shown to enhance its wear resistance because the network prevents excessive plasticity at the contact surfaces. In contrast, the isolated carbides in the wrought form are less effective so that the wear surfaces show roughness caused by plasticity, leading to an enhanced wear rate. Similar conclusions are reached with respect to the cutting behaviour of tool inserts made from the cast and wrought steels.

On the wear resistance of high-speed steels

The wear resistance of cast and strained high-speed steels are evaluated and compared, and the regularities of variations in their structure and properties depending on the austenitizing temperature are described. The impact of modification on the wear resistance of tungsten-molybdenum high-speed steels has been studied. Data on the steels with improved wear resistance are reported

Properties of double dispersed tool steels

The aim of this study was to develop a new tool material, which combines the toughness of Hot-Work Steel (HWS) with the wear resistance of High-Speed Steel (HSS). This has been realised via powder metallurgy by blending HWS and HSS powders. The blend, which may contain up to 30 vol.% of high-speed steel powders (grain size 150 microns), is subjected to Hot Isostatic Pressing (HIP). This results in a microstructure that shows a double dispersion of coarse HSS clusters with dispersed small carbides (< 5 microns) in a martensitic HWS matrix without carbides. The new materials can be treated to produce hardness levels of between 40 and 60 HRC. The materials were examined with respect to their wear resistance and fracture toughness and the results obtained were correlated to the microstructure. It is shown that the wear rate of the double dispersed material decreases as the HSS content increases without causing a significant reduction in fracture toughness.

Microstructure and wear resistance of high-speed steel treated with intense pulsed ion beam

The structural and phase transformations occurring in the near-surface layers of pre-quenched W 6Mo 5Cr 4V 2 high-speed steel (HSS) subjected to intense pulsed ion beam (IPIB) melting have been investigated. The effect of IPIB irradiation on wear resistance of the HSS has also been studied. The IPIB consists mainly of C n+ (70%) and H + (30%), with a high beam current density of 80 A/cm 2, acceleration voltage of 250 kV and pulse duration of 70 ns. Samples were bombarded with 1, 3 and 5 pulses. Electron microscopy and X-ray diffraction have revealed that after IPIB irradiation the initial martensite in the near-surface layer of HSS changed into austenite and residual stresses were produced. Refined crystal grains in the near-surface layer having a thickness up to ∼2 μm were also observed. Redistribution and interlace of dislocations in the irradiated samples were generated under the impact of the shock wave. With increasing number of pulses, gradual liquid-phase dissolution of the M 6C carbides occurred in the near-surface layer and produced nanocrystalline MC. This process results in the decrease of martensite crystal (α-phase) and increase of the austenite (γ-phase) content and the dispersion of carbides. The wear resistance of the HSS was improved by a factor of 2, which is explained by the formation of metastable nanocrystalline phases as well as by the presence of residual stresses and the redistribution dislocations.

Increasing the wear resistance of surface layers of high-speed steel by electric-spark alloying and laser treatment

How the combined action of high-energy spark alloying and laser treatment affect the wear resistance of high-speed steel cutting tools has been studied. That action has been found to form a strengthened layer of composite refractory compounds on the tool surface, thus making it hard and wear-resistant, and create a protective barrier that reduces the adhesive interaction of the cutting tool with a chip. The tribological properties and the durability of the cutting tool can be enhanced by alloying the surface layer with elements and compounds that form stable oxides tightly bonded to the substrate.

Reducing wear of high-speed steel cutting tools by spark hardening

“Spark hardening” is a process by which a wear-resistant material is deposited on the surface of steel components and cutting tools by the action of electric sparks. The deposited material forms a fused hardened skin. The wear resistance of high-speed steel cutting tools can be improved by this process and an increase in tool life of about four times has been obtained. The performance of the tools depends on the spark energy and the specific time of treatment.