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Friday, 8 September 2017

Optimizing deoxidation and desuIphurization during vacuum induction melting of alloy 718 is now online and free to members of IOM3.

My seminal paper:

Optimizing deoxidation and desuIphurization during vacuum induction melting of alloy 718, J. Alexander,

The above referenced scientic publication is an indispensible reference of fundamental importance for the very highest quality (and not mentioned higher productivity) manufacturing by Vacuum Induction Melting (VIM)  of a large family of alloys,(high intergrity materials such as aero-engine quality Nickel based superalloys (and similar materials). My paper was first briefly reported at a Superalloy meeting in London UK (1982) then fully published in 1984-85, in the, then new, journal, Materials Science and Technology (IOM3, UK). At the time of this work the only acceptable method of manufacturing to the very high standards and specifications of materials used in the manufacture of aeronatic engines was by the use of so called virgin materials, as opposed to the use of recycled materials (eg. previously manufactured and/or used alloys of same or simalar grades.)

(NB a typical aeroengine such as those powering an Airbus or Boeing Aircaft to name two is require to withstand 50 000 hrs of flight).

Now in this work sucessful trials and procedures were developped by which the use of either virgin raw material melt charges or carefully selected recycled materials (superally scrap) in the melt charge process equally reach the same very high standards required for aeroengine application.

This work has now been made available, online, by the UK Institute of Minerals,Mining and Materials (IOM3) and their publisher (Taylor and Francis) UK. As mentionned this work is now freely available to members of IOM3 via their website www.iom3.org.

The work was carried out while I, the author, worked at Imphy SA, now APERAM, in France (Burgandy Region, Department 58, La Nièvre).

My role was absolutely indispensible in the acceptance of the project  by our steelworks  and our chemical analysis laboratory in response to  GE-SNECMA's extremely high aero-engine main shaft requirements obtaining adheshion of both Steelworks and Chemistry Lab (90 or so Chem Elements to be analysed in order to satisfy the imposed specification of the client GE-SNECMA consortium for the above work to begin. (I had previous engaged a college student to carry out an indepth inventory which allowed us to know all unwanted fragilising trace element ever encountered in over a historically long period within this long and rightly proud plant (company).

With his trace element inventory and subsequent analysis by use of a Venn Diagramme I was able to reduce the internal trace element spec to a few known and easy to analyse chem. elements in our inhouse Chem Lab. The indispensible adhesion of Meltshop and Chemistry Lab. was thus gained. Melt trials were programmed. A team composed of researchers and meltshop specialists was set up to follow the procedures in which improved, but difficult to handle, desoxidation and desulphurisation agents were to be introduced. During the first melt trial as the refining took place and timide ajustments were made following chemical analysis of specimens.  The appointed research colleague on first melt- incidentally qualified to PhD level!!! "threw in the towel" while, I, as the experienced steel-melt-shop quality process engineer, stayed overseeing the initial meltshop personel and continued throughout the night making sucessive adjustments to the chosen chemical agents. At 5am in the morning the Chem. Lab anounced that all oygen and sulphur had been removed. "YES...EUREKA"! While others doubted the feasability the adjustments required to suceed and special precautions were published,  In fact I finished these adjustments alone throughout the night. At about 5am in the morning, the laboratory was able to announce to me, virtually zero oxygene and sulphur in the melt.  This work also showed that recycled materials can prove equally acceptable as the standard so called "virgin raw material" until then the only acceptable raw materials choice to meet the Aeronautics Authoritities stringent Safety Specifications and Regulations. And of course various improved economics and sustainability of ever rarifying strategic materials. NB. Highly reliable "aeronautic quality scrap material" was resourced via Ireland Alloys in Scotland (with thanks).

Rapidly these procedures were adopted in a wide range of Inconel & Udimet type superalloys and Hastelloys. The powder metallurgical plant was a very early adept to this breakthrough.

The overall cleanness of our  (Imphy S.A.- now APERAM)special and superalloys was greatly enhanced.

I remain available to discuss and assist companies with such improvements if required. Most of this work has been adopted in regular production. Also these VIM procedures greatly helped the desulphurization ability of ESR-Electro Slag Remelting (Nothing like taking the sulphur our before ESR! ) Other productivity improvements were achieve.

James Alexander is a Free-Lance Consultant and Translator (Bilingual French-English) 
Specialialities-process metallurgy, technology transfer (Japan-Invar for Liquid Gas Transport & India-Ministry of Defense India MIDHANI project, Hyderabad,India.

To cite this article: J. Alexander (1985) Optimizing deoxidation and desulphurization during vacuum induction melting of alloy 718, Materials Science and Technology, 1:2, 167-170, DOI: 10.1179/mst.1985.1.2.167 To link to this article: http://dx.doi.org/10.1179/mst.1985.1.2.167

Other Citations:

Sulphur Control in Nickel-Based Superalloy Production Dipl.-Ing. J. Morscheiser1 , Dipl.-Ing. L. Thönnessen2 , Prof. Dr.-Ing. B. Friedrich1 1 IME Process Metallurgy and Metal Recycling, RWTH Aachen University Intzestraße 3 52056 Aachen NB The date of my work is incorrectly referrences as 1995 (ie ten years late!!!)

((ALEXANDER, J.: Optimizing deoxidation and desulphurization during vacuum induction melting of alloy 718, in Materials Science and Technology, Vol. 1, 1995,(should be 1985) p. 167-170

and correctly cited as one would expect by Prof A.Mitchell  renowened also as a first class consultant

THE MAGNESIUM PROBLEM IN SUPERALLOYS A. Mitchell, M. Hilbom, E. Samuelsson and A. Kanagawa Dept. of Metals and Materials Engineering The University of British Columbia Vancouver, B.C., Canada, V6T lW5

4. J. Alexander: Material Science and Technology, Feb. 1985, V.l, pp. 167- 170.  

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