Fixed Time Integration-Emission Spectrochemical Analysis of Tool Steels and High Speed Steels by Unified Calibration Curves and Study of a Correction Method

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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Blockage Correction and Reynolds Number Dependency of an Alpine Skier: A Comparison Between Two Closed-Section Wind Tunnels

Proceedings ◽

10.3390/proceedings2020049019 ◽

2020 ◽

Vol 49 (1) ◽

pp. 19

Author(s):

Ola Elfmark ◽

Robert Reid ◽

Lars Morten Bardal

Keyword(s):

Reynolds Number ◽

High Speed ◽

Absolute Error ◽

Reynolds Numbers ◽

Correction Method ◽

Wind Tunnels ◽

Alpine Skier ◽

Blockage Correction ◽

Reynolds Number Dependency ◽

The Impact

The purpose of this study was to investigate the impact of blockage effect and Reynolds Number dependency by comparing measurements of an alpine skier in standardized positions between two wind tunnels with varying blockage ratios and speed ranges. The results indicated significant blockage effects which need to be corrected for accurate comparison between tunnels, or for generalization to performance in the field. Using an optimized blockage constant, Maskell’s blockage correction method improved the mean absolute error between the two wind tunnels from 7.7% to 2.2%. At lower Reynolds Numbers (<8 × 105, or approximately 25 m/s in this case), skier drag changed significantly with Reynolds Number, indicating the importance of testing at competition specific wind speeds. However, at Reynolds Numbers above 8 × 105, skier drag remained relatively constant for the tested positions. This may be advantageous when testing athletes from high speed sports since testing at slightly lower speeds may not only be safer, but may also allow the athlete to reliably maintain difficult positions during measurements.

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Numerical Investigations of Centrifugal Compressor Flows With Tip Leakage Using a Pressure Correction Method

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery ◽

10.1115/93-gt-109 ◽

1993 ◽

Author(s):

A. Tourlidakis ◽

R. L. Elder

Keyword(s):

Flow Pattern ◽

High Speed ◽

Stokes Equations ◽

Correction Method ◽

Secondary Flows ◽

Tip Clearance ◽

Physical Models ◽

Wake Flow ◽

Operating Characteristics ◽

Pressure Correction

In this paper, a three-dimensional computational model for the solution of the time-averaged Navier-Stokes equations, based on a pressure correction method and the k-ε turbulence model, is presented and implemented for the viscous flow modelling through a series of centrifugal compressors. Theoretical calculations with the current fully elliptic method are carried out and the results are compared critically with available experimental data and with results from other computational models. A radial and two backswept high-speed subsonic compressors with different geometrical and operating characteristics are analysed at design and off-design conditions. In all cases, a wake flow pattern is evident and strong secondary flows are discerned. The tip clearance effects on the relative flow pattern are found to be important and are appropriately simulated. The predictive capability of the current flow model is judged to be encouraging taking into consideration the limitations of the physical models and the numerical schemes involved in the computations.

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