R6M5 High-speed Steel Research Articles

Cutting tests for end-milling radius cutters of high-speed steel with and without diffusion coating

Results of laboratory cutting tests of an end-milling radius cutter of R6M5 high-speed steel with a diffusion complex coating (C-B-N) and without coating are given. The relationship between the wear kinetics and tool life is determined. Under the accepted test conditions, the tool life with coating is shown to be 1.6 times higher than the tool life of similar milling cutters without coating. The higher tribological stability of the coating in the course of wear is verified by the results of electron-microscope analysis of the worn surfaces of milling cutters.

Combined plasma-vacuum processing of wood-cutting tools

The influence of the regimes of the combined vacuum-plasma processing on the structure, phase composition, and microhardness of the modified layers and the titanium carbonitride coatings formed on samples of R6M5 high-speed steel is investigated. The combined processing involves ion nitration in a glow discharge plasma and the deposition of coatings using arc plasma.

A method for improving the structure and properties of the material of cast preforms from waste high-speed steel R6M5

A method for fabricating cutting tool preforms from waste high-speed steel R6M5, which includes stages of progressive improvement of the microstructure and mechanical properties of the material (electroslag mold remelting followed by pressure treatment by extrusion and heat treatment in the chosen mode), is presented.

Alternative technology of thermomechanical treatment of high-speed tungsten-molybdenum steel R6M5

A several-pass alternative process of thermomechanical treatment based on the discovered regular features of the effect of superplasticity is developed. Optimum modes of treatment for high-speed steels of type R6M5 are suggested. The technology has been patented in the Russian Federation and belongs to processes of environmental management.

Modifying Cast Tungsten-Molybdenum High-Speed Steels with Niobium, Zirconium, and Titanium

The influence of modifying additives of niobium, zirconium, and titanium on the structure and properties of cast tungsten-molybdenum high-speed steels R6M5 and R6M5K5 is studied. Results of metallographic and x-ray diffraction analyses and of studies of fracture surfaces of the steels after casting, annealing, hardening, and tempering are discussed. The relationship between structural parameters, the degree of contamination of the metal by nonmetallic inclusions, and mechanical properties is established. It is shown that modifying with the mentioned elements in optimum amounts primarily promotes an increase in the impact toughness and wear resistance of the metal.

Use of REM-Based Modifying Agents for Improving the Structure and Properties of Cast Tungsten-Molybdenum High-Speed Steels

Special features of the structure and properties of cast high-speed steels R6M5K5 and R6M5 modified by REM-based additives, i.e., ferrocerium in a design amount of 0.1, 0.3, 0.6, and 1.2% and silicomishmetal and alumoyttrium in a design amount of 0.1, 0.3, and 0.6% are studied. Results of metallographic, x-ray diffraction, fracture surface, and microscopic x-ray spectral analyses of the steels after casting, annealing, hardening, and tempering are discussed. It is shown that the modifying changes the chemical composition, morphology, and distribution of the carbide component in the steels. Relation between the structural parameters and the characteristics of mechanical properties is determined.

Structure and Properties of Cast Rapidly Cooled High-Speed Steel R6M5

Special features of the structure and properties of cast high-speed steel R6M5 cooled from a solid-liquid condition at various rates are considered. Liquid metal is cast into a permanent graphite mold heated to 20, 300, and 600°C and cooled in open air or in liquid nitrogen. It is shown that with increase in the cooling rate the degree of alloying of the solid solution and the amount, morphology, and distribution of the carbide component of the steel vary during the crystallization. The parameters of the structure are shown to depend on the properties of the metal (hardness, strength, impact toughness, heat resistance, and wear resistance). Results of wear tests of cast metal-cutting tools are presented.

Borosulfocarbonitriding of Cutting Tools in Electrolyte Plasma

The use of electrolytic deposition for hardening cutting tools from high-speed steel R6M5 is considered. The composition of the electrolyte is chosen so as to provide the formation of a composite borosulfocarbonitride layer on the cutting tool (cathode). A distinctive feature of the suggested saturation technique is the formation of an ionized gas atmosphere heated to 950°C around the cathode (the treated tool) due to the high current density. As a result, a diffusion layer 0.1 mm thick forms on the surface of the tool in a very short time (50 – 90 sec). Due to the short duration of the discharge the tool has no time to soften. The phase composition of the surface layer provides high hardness and wear resistance of the tool.

Phase Composition of Electrospark Tungsten Carbide-Based Coatings after Heating and Isothermal Soaking

A study of phase formation on electrospark coatings with WC ― Co ― Cu electrodes on R6M5 high-speed steel during isothermal heat treatment at the operating temperature of the coating. Copper tungstate CuWO 4has been found to form, with its crystal lattice coherently bound to the basic carbide phase of the coating, tungsten monocarbide, through tungsten semicarbide as intermediary. The results complement the data on phase formation during the application of WC-based coatings and during their subsequent use with sliding friction.

Integrated technology for casting-crystallization heat treatment in the continuous casting of high-speed steels

1. A new method has been developed for obtaining cast metal products. The method is based on combining crystallization processes and processes which occur during heat treatment of the crystallizing metal in a single production cycle (CCHT). 2. For the first time in domestic practice, combined cycles of CCHT have been used in the continuous casting of high-speed steel R6M5 on a radial continuous caster. The casting was done at the Serp i Molot plant. 3. Replacing casting in ingot molds by continuous casting shortens the production cycle for high-speed steels by a factor of more than eight and decreases the number of processing operations and conversions threefold. It has also been shown that it is possible to roll high-speed steel cast on a continuous caster by the proposed technology, without the need for forging. 4. The quality of finished products of steel R6M5 made by the new technology meets the requirements of GOST 19265-73. Tools made from an experimental batch of the steel lasted 20% longer than tools made from steel produced by the usual technology.

Electrospark alloying followed by laser treatment of high-speed steel cutting tools

The effect of electrospark and laser alloying with WC-, TiC-, and TiN-based electrodes on the physicomechanical and working properties of the high-speed steels R6M5 and R6M5K5 was investigated. Laser treatment of electrospark coatings based on refractory compounds increased hardness and heat resistance, and improved the contact properties of cutting tools in their interaction with the chip, thus increasing wear resistance. The optimal conditions of electrospark and laser alloying were determined.

A thermal analysis study on nitriding R6M5 high-speed steel powder

A thermogravimetric analysis has been applied to processes in R6M5 high-speed steel powder thermochemically treated in ammonia. Temperature ranges have been identified for the adsorption of nitrogen, nitriding, and denitriding. To prepare a powder containing nitrogen of superequilibrium concentration, conditions have been defined for maximum nitrogen uptake, fullest appliance of phase transitions, and diffusion: isothermal hold at 520°C for 20 min and at 620°C for 60 min.

Formation of directional austenite-carbide structures during the carburization of complex alloyed steels

In the present work the structure of the surface layer of low-alloy steels analogous to the high-speed steels R6M5, R3M3, and R3M3F2 (see Table i) after carburization was investigated. The steels were melted in induction furnace IST-016 in a crucible with a basic magnesia lining. Thick-walled sleeves 87 mm in external and 25 mm in internal diameter were produced by centrifugal casting. Commercial iron and ferroalloys were used in the preparation of the steel melts.

Structural changes in steel R6M5 due to surface melting by electron beam

When high speed steel R6M5 is molten by an electron beam, rapid cooling has the result that in the process of crystallization a finely disperse structure forms, and the width of the secondary branches of its dendrites depends on the cooling rate in the process of crystallization. In the molten zone we find finely disperse metastable carbide type M2C, the content of alloying elements (W, Mo, V) in the solid solution increases, martensite forms, both rack and lamellar one. In addition to that, δ-ferrite, was discovered in the molten zone; this is ascribed to the suppression of the peritectic reaction.

Heat treatment of high-speed steel with continuous laser

1. When preliminarily hardened high speed steel, tempered at 350–560°C, is treated by a continuous CO2-laser with energy density J=34±3 MJ/m2, a strengthened layer with maximal thickness and hardness forms. 2. Accelerated heating by laser beam to temperatures in the range between Ac3 and Tpl and practically instantaneous cooling to normal temperature at rates of more than 104°C/sec give rise to a highly disperse (in melting) and fine-grained structure recrystallized by precipitation hardening (in quenching in the solid state) and consisting of martensite, residual austenite (in increased amount), and carbides (in a small amount). The intense dissolution of ledeburitic carbides type M6C in the laser-hardened zone causes additional alloying of the solid solution, increased stability of the residual austenite, and super-sautration of the finely accular martensite. 3. The decomposition of residual austenite and the intense dispersion hardening in the process of tempering at 560–600°C 1 h increase the hardness of the laser-hardened layer of high speed steel R6M5 by 2–4 HRCe, and resistance to tempering by 40–50°C compared with conventional heat treatment. The absence of coarse carbide particles in the hardened layer reduced the probability of brittle failure by chipping in operation of the cutting tool.

Effect of superplastic deformation using different stress modes on the structure of high-speed steels

1. During superplastic deformation (SPD) of steel R6M by tension, up setting, and direct extrusion a more dispersed structure develops as a result of refinement and spheroidizing of the carbide phases and an increase in the uniformity of their distribution. This effect occurs to a greater extent during tension loading. 2. In powdered steel 10R6M5-MP, which possesses a greater degree of initial dispersion and uniform distribution of the carbide phases than in steel R6M5, there also occurs an increase in the dispersion and uniform distribution of the carbide phases. However, this effect is only observed during SPD by tension and upsetting. During direct extrusion of steel 10R6M5-MP the dispersion and uniform distribution of the carbide phases remain at the same level they were in the initial condition or become less so with increase in the compressive stress level. 3. The greatest degree of increased dispersion and uniform distribution of the carbide phases in high-speed steels R6M5 and 10R6M5-MP occurs during SPD by tension loading. 4. The more dispersed the initial structure, than the more strongly do compressive stresses inhibit diffusion processes. 5. Changes in the superplastic indices during transfer from tension to compression loading may be associated with a change in the contribution of diffusion creep to the superplastic process. 6. The increased dispersion and uniform distribution of the carbide phases in high-speed steels R6M5 and 10R6M5-MP due to SPD is a function of the initial dispersion and uniform distribution of the carbides and of the type of stress scheme used.

Mechanical and Frictional Properties of Tool Steels Exposed to HPIB Irradiation

en

Extraction of tungsten and molybdenum from grinding sludge of high-speed tool steels

Investigations were carried out into the process of oxidizing roasting the sludge waste of R6M5 high-speed tool steel to extract, from the sludge, tungsten and molybdenum by sublimating and condensing the oxides.

Corrosion damage of the surface of high-speed tool steel in acid-inhibitor pickling

Profilograms were recorded of the surface of 20-mm-diameter 1.5-mm-thick specimens prepared from hardened and tempered R6M5 high-speed tool steel (62 HRC) and also of similar specimens subjected to the action of pure hydrochloric acid etching solution and of the same solutions with additions of KhOSP-10, KhOSP-10D, and urotropin inhibitors at 30, 60, and 90/sup 0/C for 4.0, 2.0, and 0.5 h, respectively. The analysis of corrosion damage and determination of the surface finish of the steel made it possible to develop the optimum method of acid-inhibitor pickling specifying the addition to the acid of 1.5 g/liter KhOSP-10 inhibitor and a temperature of 30/sup 0/C. This suppressed the corrosion rate, hydrogen impregnation and embrittlement, decarburization of the steel, and sensitivity to crack formation, and reduced the number of scrapped parts.

Reduction of R6M5 high-speed steel powder

On the basis of a thermodynamic calculation of the reduction of iron., chromium, and vandanium oxides and of experimental data, the following optimum reduction annealing conditions were chosen for R6M5 powder from swarf: temperature 900–950°C, vacuum corresponding to 1.3–0.13 Pa, and holding time 2 h. In this powder about 25% of all oxygen was found to be present in the difficult-to-reduce chromium and vanadium oxides and 75% in iron oxides. An expression is proposed for calculating the amount of carbon that should be added to the powder.