British Stainless Steel Association Conference 2008

Recent raw material market fluctuations require us to reconsider the technical functions of
stainless steel to provide economic solutions for manufacturers, fabricators, finishers, architects
and end users. NBS Technical author John Scott attended the BSSA conference in June and reports on consequences for the construction industry.

Costs for the end consumer depend on supply and demand which, for stainless steel, have traditionally been relatively stable. A decade ago there was a lack of major investment in mining exploration, new production resources and purification plants. This under-provision led to volatility in the commodity prices of raw materials such as molybdenum, nickel and ferrochrome, which sent shock waves through the stainless steel industry.

There is increasing demand for stainless steel – particularly in Brazil, India and China – which to a certain extent will be offset by plans to increase production capacity in these countries. There is also anticipated new demand for stainless steel over the next decade from the energy supply sector, for increase in nuclear and wind generated power supplies. Its green credentials might add to the appeal (see Catherine Houska, Wrapped in stainless steel, The Construction Specifier, August 2008 (48-62) – see www.csinet.org). Couple this new demand with normal demand (e.g. building, civil and other engineering projects) and product manufacture (e.g. bathroom and kitchen fittings), and there will almost inevitably be cost increases. Specifiers will need to be more selective in the grade of stainless steel required to fulfil the functional requirements of the design.

Metallurgy

Molybdenum, nickel and ferrochrome are fundamental to malleability and corrosion resistance of stainless steel. Small percentage variations in their content have major effects on the qualities and finish of the stainless steel. Some well respected manufacturers of domestic components have already started to change from traditional austenitic to ferritic grade stainless steel. Similarly in other sectors such as the aircraft industry, research and development is resulting in shifts to duplex and other specialist grades. The construction industry can benefit from these new steel types and developments providing we understand the technology or, more precisely, the metallurgy behind their usage. Also, more attention will need to be given to the finishing of components.

There will be pressure to reduce the expensive materials content, which will affect corrosion resistance and workability. Increased understanding of these properties and their effect on fabrication, and of finishing required for components, particularly with complex shapes or in exposed locations, will become critical. Evidence of failures in some recent prominent projects were illustrated at the conference. Traditional knowledge relating to the use of well known grades of stainless steel will no longer be satisfactory. To optimise the properties, availability and economic cost of components, a more considered and scientifically-based selection will be necessary.

Architects, engineers and other design professions specifying stainless steel are generally not metallurgists. Yet they need to become more conversant with the developments and changes which economic conditions are forcing on the supply and use of stainless steel. The stainless steel industry needs to encourage education packages to enable a fuller knowledge of stainless steel among these important people.

Nomenclature

The change of nomenclature, to grades with a scientific basis, does not seem to have worked. The problem is that non-metallurgist specifiers do not understand the technical implications of a steel named X5CrNi18-10 or X5CrNiMo17-12-2 (see BS 10088-2 or -3). This nomenclature is too complex and needs to be simplified. True, we can specify by grade number, e.g. 1.4301 or 1.4401, but that still requires a search through the designation names and knowledge of the technical implications. Yet, for the whole conference, the delegates referred to steels using the previous system by referring to withdrawn standards BS 1449-2 and BS 970-1, and by quoting grade 304 or 316 as well as other 'group' headings such as 200 or 400 series steels. If the leaders of the stainless industry don't use the current nomenclature, it does not set an example for the rest of us to use it.

We need a system of user-friendly definitions. BS EN 10088-1:2005 Stainless steels. List of stainless steels includes over 150 variations in nine tables, yet no more than a dozen or so types of stainless steel were referred to throughout the conference. Yes, metallurgical knowledge is paramount, but for the most-used construction steel grades surely a simplified system could be created, even one as simple as grade A, B or C and a suffix for the finish. This would be far easier to specify and consequently less risky.

Stainless steel is an essential part of the construction industry. If we are to make the best and most economic use of it in the future then the specialist aura needs to be removed and specifiers need to better understand its properties and use. Supplier and specifier will need to cooperate in the future development and use of stainless steel.

Written September 2008

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