Alloying Liquid Metal with Nitrogen from Electric ARC Plasma

476 Pages·1999·3.96 MB·English

by  V I Lakomskii

Alloying Liquid Metal With Nitrogen From
title: Electric Arc Plasma : Theoretical
Fundamentals
author:
publisher: Cambridge International Science Publishing
isbn10 | asin: 1898326533
print isbn13: 9781898326533
ebook isbn13: 9780585237459
language: English
subject Alloys.
publication date: 1999
lcc: TN690A55 1999eb
ddc: 669.95
subject: Alloys.
Page iii
Alloying Liquid Metal with Nitrogen from
Electric Arc Plasma
Theoretical Fundamentals
V I Lakomsky
E.O. Paton Electric Welding Institute
National Academy of Sciences of Ukraine, Kiev
CAMBRIDGE INTERNATIONAL SCIENCE PUBLISHING
Page iv
Published by
Cambridge International Science Publishing
7 Meadow Walk, Great Abington, Cambridge CB1 6AZ, UK
http://www.demon.co.uk/cambsci/homepage.htm
First published 1999
© V I Lakomsky
© Cambridge International Science Publishing
Conditions of sale
All rights reserved. No part of this publication may be reproduced or
transmitted in any form or by any means, electronic or mechanical,
including photocopy, recording, or any information storage and
retrieval system, without permission in writing from the publisher
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN 1 898326533
Production Irma Stupak
Printed by Pear Tree Press Ltd., Stevenage, Herts., SG1 2BH
Page v
Preface
At the beginning of the Sixties, the second importand method of
special electrometallurgy was developed in the former Soviet Union
on the basis of electroslag remelting: plasma-arc remelting of steels
and alloys in a water-cooled continuous solidification mold (PAR).
Pioneering work in this area was carried out by the E.O. Paton
Electric Welding Institute, National Academy of Sciences of Ukraine,
Kiev. Experts at the Institute also developed the remelting method and
designed laboratory and industrial furnaces. The Institute also carried
out investigations into all aspects of plasma remelting: examination of
the processes of high-temperature interaction of gases with liquid
metals, development of the remelting technology of steels and alloys
for different applications. The properties of remelting metal were
investigated in cooperation with metallurgical plants and branch
Institutes.
Plasma-arc remelting furnaces were rapidly constructed and
introduced in ferrous and nonferrous metallurgy plants, aviation and
military industry.
One of the many of technologies used in this area was alloying with
nitrogen of liquid chromium-nickel and chromium-nickel-manganese
steels from the gas phase, combined with the process of remelting the
steel. Already at the end of the Sixties, Soviet plants melted 500 kg
steel ingots designed for facing the combustion chambers of aviation
turbine engines where the nitrogen content was 1% or higher (usually,
nitrogen content did not exceed 0.5%). The produced high-nitrogen
steels were characterised by a favourable combination of physical-
mechanical and chemical properties (strength, plasticity and corrosion
resistance) and represented a new class of metallic materials.
At that time, no special interest was paid to this method of processing
steels in foreign plants. Only in the Eighties, initially in Germany and
then in France and Sweden, there was a sudden increase in the number
of investigations concerned with the production and properties of
high-nitrogen steels. The number of investigators interested in this
problem have been continuously increasing. International conferences
on high-nitrogen steels were organised. The investigators, having no
information on the work of the E.O. Paton Electric Welding Institute,
started work to find their own solutions for alloying experimental
steels with nitrogen in large quantities and preventing the precipitation
of nitrogen during welding and solidification of liquid metal. This
situation was the reason for the publication, in 1992 in Kiev, of a
monograph by the author, named 'Interaction of Diatomic Gases with
Liquid Metals at Higher Temperatures'. However, because of the
language barrier, this book was not known abroad. In addition, as a
result of the disintegration of the book market in the former USSR,
Page vi
the book has not even reached readers in Russia and other CIS
countries.
This second edition of the book differs from the first one by a more
detailed explanation of relatively complicated problems of alloying
liquid metals with nitrogen from electric arc plasma. The author hopes
that the book will be useful to experts working in electrometallurgy
and welding and, possibly, will initiate new investigations in this
interesting area.
The author is grateful to Mr Riecansky of the Cambridge International
Science Publishing for publishing this book with such specific and
difficult terminology.
V I LAKOMSKY
<><><><><><><><><><><><>
About the Author
Professor V.I. Lakomsky was born in 1926 in Kramatorsk (Donbass
region) in a family of a metallurgist. In 1950, he completed his
education at the Zaporozh'e Engineering Institute in casting and in
1954 he finished his post-graduate the Academy of Sciences of
Ukraine. This dissertation dealt with gases in cast iron; his scientific
supervisor was Prof. V. Yavoiskii, the well-known expert on gases in
metals.
Since 1957, on the basis of an invitation of Academician B.E. Paton,
the VI Lakomsky has been working at the E.O. Paton Electric
Welding Institute, National Academy of Sciences of the Ukraine,
Kiev.
At the Institute, Professor Lakomsky founded, developed and headed
the scientific section concerned with the high-temperature interaction
of liquid metals with gases in the plasma state.
The results of studies of Professor Lakomsky have been applied in
practice in a new process of special electrometallurgy: plasma-arc
remelting (PAR) steels and alloys. This subject was also the content of
his PhD dissertation in 1969.
For the development and introduction of PAR, Professor Lakomsky
was awarded the State Prize of Ukraine in 1980.
In 1992, Professor Lakomsky was elected a Corresponding Member
of the National Academy of Sciences of Ukraine, and in 1998 he
received the title: Honoured Activits in Science and Technology in
Ukraine.
Professor Lakomsky has published five monographs and more than
300 scientific articles. This is his sixth book.
Page vii
List of conventional symbols
A - enthalpy coefficient in the equation of isobar of gas solubility in
metal
ag - thermodynamic activity of gas dissolved in metal
B - entropy coefficient in equation of isobar of gas solubility in metal
D - coefficient of molecular gas diffusion in metal, cm2/s
De - Damköhler's criterion
- parameter of the first order of magnitude of gas interaction with
element i in metal solution
- coefficient of thermodynamic gas activity in metal alloyed with
element i
- Gibbs' partial energy of a gas dissolved in metal, J/(g·atom)
-Gibbs' molar energy of a gas in gas phase, J/(g·mole)
- relative partial Gibbs' energy of a gas dissolved in metal,
J/(g·atom)
[G] - gas concentration in metal, % mass
- partial enthalpy of a gas dissolved in metal, J/(g·atom)
-molar enthalpy of a gas in gas phase, J/(g·mole)
- relative partial enthalpy of a gas dissolved in metal or dissolution
heat of a diatomic gas in metal, J/(g·atom)
-standard partial enthalpy of a gas dissolved in metal, J/(g·atom)
h - Plank's constant, J·s
Ia - current of electric arc, A
Ks - equilibrium constant of reaction of dissolving a diatomic gas in
metal (Sieverts' constant), %·atm-1/2
- virtual coefficient of proportionality between gas concentration in
metal and in electric arc atmosphere, %·atm-1/2
- plasma sorption coefficient, %·atm-l/2
- standard gas solubility in metal at appropriate T, %·atm-1/2
Page viii
k - Boltzmann's constant, erg/K
m - atom mass, g
N0 - Avogadro number
Ng - gas concentration in metal, at.fractions
ng - mole number of gas dissolved in metal
PS - gas mixture pressure, arm or Pa
Pg2 -partial gas pressure in gas phase, atm or Pa
Pg - Prandtl number
- heat of evaporation of metal, kJ/mol
- parameter of the third order of gas interaction with element i in
metal solution
- parameter of the second order of gas interaction with element i in
metal solution
R - universal gas constant, J/(g·mole)
Re - Reynolds number
r - radius of gas bubble in liquid metal, cm
S - total area of gas interaction with liquid metal, cm2
Sa - liquid metal area heated by gas plasma flow through which gas is
absorbed, cm2
Sd - liquid metal area heated by gas plasma flow through which a gas
evolves from metal bath, cm2
Sc - Schmidt number
Sg - partial entropy of a gas in metal solution, J/(g·atom·K)