Laser—ultrasonic formation of melts of high-speed tool steels

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.

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Betrachtungen zum Gefügeaufbau der Schnellarbeitsstähle / Observations on the Microstructures of High Speed Tool Steels

Practical Metallography ◽

10.1515/pm-1975-120801 ◽

1975 ◽

Vol 12 (8) ◽

pp. 393-406

Author(s):

Alfred Fischer ◽

Erich Kohlhaas

Keyword(s):

High Speed ◽

Tool Steels

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Tool Steels

10.31399/asm.tb.spsp2.t54410621 ◽

2015 ◽

pp. 621-645

Keyword(s):

Wear Resistance ◽

Phase Transformations ◽

Retained Austenite ◽

High Speed ◽

Cold Work ◽

Heat Treating ◽

Alloy Design ◽

Tool Steels ◽

Evolution Of Microstructure ◽

Alloying Principles

Tools steels are defined by their wear resistance, hardness, and durability which, in large part, is achieve by the presence of carbide-forming alloys such as chromium, molybdenum, tungsten, and vanadium. This chapter describes the alloying principles employed in various tool steels, including high-speed, water-hardening, shock-resistant, and hot and cold work tool steels. It discusses the influence of alloy design on the evolution of microstructure and properties during solidification, heat treating, and hardening operations. It also describes critical phase transformations and the effects of partitioning, precipitation, segregation, and retained austenite.

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Preparation of Molybdenum High Speed Tool Steels with Addition of Niobium Carbide by Powder Metallurgy Techniques

Materials Science Forum ◽

10.4028/www.scientific.net/msf.802.102 ◽

2014 ◽

Vol 802 ◽

pp. 102-107 ◽

Cited By ~ 1

Author(s):

Oscar Olimpio de Araújo Filho ◽

Rodrigo Tecchio Antonello ◽

Cezar Henrique Gonzalez ◽

Severino Leopoldino Urtiga Filho ◽

Francisco Ambrozio Filho

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Powder Metallurgy ◽

Liquid Phase ◽

High Speed ◽

Niobium Carbide ◽

High Energy ◽

Tool Steels ◽

Vacuum Sintering ◽

Scanning Electron

High speed steels processed by Powder Metallurgy (PM) techniques present better mechanical properties when compared with similar steels obtained by the conventional process of cast to ingot and hot working. PM techniques produce improved microstructures with smaller and better distribution of carbides. Liquid phase sintering high speed steel seems to be a cheaper processing route in the manufacturing of tool steels if compared to the well-known and expansive hot isostatic pressing high speed steels. The introduction of niobium as alloying element began with the object of replacing elements like vanadium (V) and tungsten (W). Phase liquid sintering consists in a manufacturing technique to process high speed steels by powder metallurgy. The aim of this work of research is to process and obtain AISI M2 and M3:2 with and without the addition of niobium carbide by high energy milling, cold uniaxial compaction and vacuum sintering in the presence of a liquid phase. The powders of the AISI M2 and M3:2 were processed by high energy milling adding a small quantity of niobium carbide (6% in mass), then the powders were characterized by means of X-ray diffraction (XRD) and scanning electron Microscopy (SEM) plus energy dispersion spectroscopy (EDS) in order to evaluate the milling process. The powders of the AISI M2 and M3:2 with the addition of niobium carbide (NbC) were uniaxially cold compacted and then submitted to vacuum sintering. The sintered samples had their microstructure, porosity and carbide distribution observed and evaluated by means of Scanning Electron Microscopy (SEM) and the mechanical property of hardness was investigated by means of Vickers hardness tests. At least five samples of each steel were investigated.

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