scholarly journals Modeling of structural transformation kinetics in steels during their heat treatment

2021 ◽  
Vol 344 ◽  
pp. 01015
Author(s):  
Liudmila Roslyakova ◽  
Vladimir Paukov ◽  
Aleksandr Besedin ◽  
Vadim Suchilkin
Keyword(s):  
Heat Treatment ◽  
Structural Transformation ◽  
Growth Kinetics ◽  
Classical Theory ◽  
Carbide Phase ◽  
Calculated Data ◽  
Metals And Alloys ◽  
Transformation Kinetics ◽  
Phase Growth ◽  
Made In

Analysis of carbide phase growth kinetics during carburizing of steel has been made in this paper, using experimental and calculated data obtained according to the classical theory of transformations in metals and alloys.

scholarly journals A New Systematic Approach Based on Dilatometric Analysis to Track Bainite Transformation Kinetics and the Influence of the Prior Austenite Grain Size

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 324
Author(s):  
David San-Martin ◽  
Matthias Kuntz ◽  
Francisca G. Caballero ◽  
Carlos Garcia-Mateo
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Prior Austenite ◽  
Bainitic Transformation ◽  
Transformation Rate ◽  
Transformation Kinetics ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

This investigation explores the influence of the austenitisation heat treatment and thus, of the prior austenite grain size (PAGS), on the kinetics of the bainitic transformation, using as A case study two high-carbon, high-silicon, bainitic steels isothermally transformed (TIso = 250, 300, 350 °C), after being austenised at different temperatures (γTγ = 925–1125 °C). A methodology, based on the three defining dilatometric parameters extracted from the derivative of the relative change in length, was proposed to analyse the transformation kinetics. These parameters are related to the time to start bainitic transformation, the time lapse for most of the transformation to take place and the transformation rate at the end of the transformation. The results show that increasing the PAGS up to 70 µm leads to an increase in the bainite nucleation rate, this effect being more pronounced for the lowest TIso. However, the overall transformation kinetics seems to be weakly affected by the applied heat treatment (γTγ and TIso). In one of the steels, PAGS > 70 µm (γTγ > 1050 °C), which weakly affects the progress of the transformation, except for TIso = 250 °C, for which the enhancement of the autocatalytic effect could be the reason behind an acceleration of the overall transformation.

Evaluation of Martensite Fraction in 1026 Steel by Infrared Thermography Combined with the Koistinen-Marburger Model

2016 ◽  
Vol 869 ◽  
pp. 411-415
Author(s):  
Dimitry V. Bubnoff ◽  
Mariana M.O. Carvalho ◽  
Carlos Roberto Xavier ◽  
Gláucio S. da Fonseca ◽  
José Adilson de Castro
Keyword(s):  
Heat Treatment ◽  
Phase Transformations ◽  
Infrared Thermography ◽  
Martensite Transformation ◽  
Infrared Camera ◽  
Martensite Formation ◽  
Transformation Kinetics ◽  
Temperature Distributions ◽  
Martensite Fraction ◽  
Model Adjustment

In the present work, the martensite formation during heat treatment of 1026 steel was studied in order to acquire process knowledge and reinforce the effectiveness of infrared thermography method to evaluate the temperature distributions. Several tests were carried out and monitored by an infrared camera and thermocouples. Martensite fraction was evaluated with the aid of the Koistinen-Marburger model and adequate parameters describing phase transformations were obtained for 1026 steel samples. This research revealed the need of model adjustment in order to accurately describe the martensite transformation kinetics according to experimental results.

Vapor Phase Growth of Carbon Microcoils / Nanocoils

2005 ◽  
Vol 23 ◽  
pp. 387-0
Author(s):  
S. Yang ◽  
X. Chen ◽  
S. Motojima
Keyword(s):  
Heat Treatment ◽  
Catalytic Pyrolysis ◽  
Double Helix ◽  
Phase Growth ◽  
High Temperature Heat Treatment ◽  
Coil Diameter ◽  
Temperature Heat ◽  
Α Helix ◽  
Temperature Heat Treatment ◽  
Single Helix

The carbon microcoils and carbon nanocoils were prepared by the catalytic pyrolysis of acetylene under the Ni and/or Fe-containing catalysts, and the growth pattern, morphology and growth mechanism of the carbon coils were examined in detail. The inner coil diameter of carbon microcoils are of several µm and coil gap from zero to several µm. The inner coil diameter of carbon nanocoils are from zero to several ten nm and coil gap from zero to several nm. The carbon microcoils are generally of double helix coils such as DNA while carbon nanocoils were single helix coils such as α-helix proteins, with spring-like or twisted forms. A catalyst grain was usually observed on the tip of carbon coil. The carbon nanocoils are almost amorphous and can be graphitized by the high temperature heat-treatment.

Heat Treatment

2013 ◽  
pp. 271-324
Keyword(s):  
Heat Treatment ◽  
Surface Hardening ◽  
Precipitation Hardening ◽  
Temper Embrittlement ◽  
Induction Hardening ◽  
Heat Treatments ◽  
Metals And Alloys ◽  
Continuous Cooling Transformation Diagrams ◽  
Transformation Diagrams ◽  
Carbon System

Abstract This chapter discusses the processes used in manufacturing to thermally alter the properties of metals and alloys. It begins with a review of the iron-carbon system, the factors that affect hardenability, and the use of continuous cooling transformation diagrams. It then explains how various steels respond to heat treatments, such as annealing, normalizing, spheroidizing, tempering, and direct and interrupted quenching, and surface-hardening processes, such as flame and induction hardening, carburizing, nitriding, and carbonitriding. It also addresses the issue of temper embrittlement and discusses the effect of precipitation hardening on aluminum and other alloys.

scholarly journals Effect of Heat Treatment of Martensitic Stainless Steel on Passive Layer Growth Kinetics Studied by Electrochemical Impedance Spectroscopy in Conjunction with the Point Defect Model

2020 ◽  
Vol 1 (1) ◽  
pp. 77-91 ◽  
Author(s):  
Ingmar Bösing ◽  
Georg Marquardt ◽  
Jorg Thöming
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Passive Film ◽  
Growth Kinetics ◽  
Martensitic Stainless Steel ◽  
Electrochemical Impedance ◽  
Defect Model ◽  
Point Defect Model

Martensitic stainless steels are widely used materials. Their mechanical and corrosion properties are strongly influenced by their microstructure and thereby can be affected by heat treatment. In the present study, the effect of different austenitizing temperatures on the passive film growth kinetics of martensitic stainless steel is studied by electrochemical impedance spectroscopy. The data was further fitted by the point defect model to determine kinetic parameters. We show that an increasing austenitizing temperature leads to a more protective passive film and slows down passive film dissolution in sulfuric acid.

scholarly journals Polar analogues of two theorems by Minkowski

1974 ◽  
Vol 11 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Kurt Mahler
Keyword(s):  
Classical Theory ◽  
Distance Function ◽  
Convex Bodies ◽  
Classical Concept ◽  
Geometry Of Numbers ◽  
Basic Theorem ◽  
The Real ◽  
Unit Hypersphere ◽  
Image Position ◽  
Made In

Since Minkowski's time, much progress has been made in the geometry of numbers, even as far as the geometry of numbers of convex bodies is concerned. But, surprisingly, one rather obvious interpretation of classical theorems in this theory has so far escaped notice.Minkowski's basic theorem establishes an upper estimate for the smallest positive value of a convex distance function F(x) on the lattice of all points x with integral coordinates. By contrast, we shall establish a lower estimate for F(x) at all the real points X on a suitable hyperplanewith integral coefficients u1, …, un not all zero. We arrive at this estimate by means of applying to Minkowski's Theorem the classical concept of polarity relative to the unit hypersphereThis concept of polarity allows generally to associate with known theorems on point lattices analogous theorems on what we call hyperplane lattices. These new theorems, although implicit in the old ones, seem to have some interest and perhaps further work on hyperplane lattices may lead to useful results.In the first sections of this note a number of notations and results from the classical theory will be collected. The later sections deal then with the consequences of polarity.

Sign in / Sign up

Export Citation Format

Share Document