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Paper originally delivered at the BSSA Conference ‘Stainless Solutions for a Sustainable Future’ held in Rotherham on 3rd April 2003. The paper describes what is happening to the world and what will continue to happen if people do not become more environmentally friendly. I looks at, for example, global warming, the UK’s energy consumption and resource depletion and then goes on to discuss the way forward by using sustainable design, execution and recycling.
Is there a COSHH (Control of Substances Hazardous to Health) information data sheet generally available for stainless steels to outline any risks associated with its handling, fabrication and use.
The valency states of chromium, including trivalent and hexavalent chromium are outlined. The valency (oxidation state) of chromium, as an alloying constituent of stainless steels, is 0 (zero). The chromium in solid stainless steels should not be regarded as a health hazard, but care should be taken with the fumes from welding stainless steels.
Youngs modulus and thermal expansion data is tabulated for a range of commonly used grades shown in BS EN 10088-1. More detailed ‘typical’ data follows for austenitic steel types only from the INCO publication ‘Austenitic chromium-nickel stainless steels-engineering properties at elevated temperatures’, including tensile and shear modulus data, Poisson’s ratio, density, thermal expansion, conductivity, specific heat and electrical resistivity.
The European ‘ELV’ directive 2000/53/EC should not have a detrimental affect on stainless steels intended for applications in automobiles. Analysis work done so far shows that the levels of lead, mercury and cadmium are well below the levels currently understood to be the limits. Stainless steels do not contain hexavalent chromium and so this requirement is not relevant.
Paper originally delivered at the BSSA Conference ‘Stainless Solutions for a Sustainable Future’ held in Rotherham on 3rd April 2003. Sustainable Development is a sociopolitical issue not a technological or economic one, which could be the reason that very few people want to know about it. It comments that the industry must demonstrate that it uses resources effectively, that they commit to continuous improvement and that its takes effective action. Doing this the industry can persuade regulators and politicians to do what the industry wants. The paper goes some way to explain why regulations relating to metals and alloys are based on risk and not simply on hazard and that stainless steel is regulated as an alloy and not as a mixture of elements. To ensure stainless steel has a bright future stainless steel and raw material suppliers need to work closely together.
Paper originally delivered at the BSSA Conference ‘Stainless Solutions for a Sustainable Future’ held in Rotherham on 3rd April 2003. This paper addresses European health and environmental regulation as it applies to stainless steel, and the threats posed to the markets for stainless steel. Mixtures, alloys and toxicity of materials are discussed and a list of EU Directives relevant to the use and application of stainless steels listed. These Directives include 76/769/EEC, the Jewellery (Jewelry) Directive, 2000/60/EEC and 98/83/EC, the EU drinking water Directives, 93/42/EEC covering medical devices and 2000/53/EC, the end-of-life vehicles Directive. Hazard classification is related to nickel content. Stainless steels are not however mixtures and so the risk classifications in relation to skin sensitisation and carcinogenic (cancer) effects are unjust. Risk phrases R43 and R40 still apply, however by European Dangerous Preparations Directive (67/548/EEC and 1999/45/EC).
Stainless steels do not have an intrinsic ‘fire rating’. Tests to assess fire resistance are performed on specific fabrications under precise conditions to BS476 parts 20, 21 (load-bearing elements) and 22 (non-load-bearing elements). Fire tests results on some specific products demonstrate the good fire resisting properties of stainless steels in building and ship bulkhead applications. (186)
Both flux- and gas-shielded processes for welding stainless steels generate fume. So does plasma arc cutting. Fume consists of both particles and gases, including ozone. Concerns that fume, particularly particles containing hexavalent chromium, is a cause of cancer have not been supported by extensive studies, although there is a slight excess of lung cancers among all welders. Therefore it is sensible to limit contact with welding fume and there are statutory requirements.
This technical paper by Dr Mike Fletcher, Metallurgical and Welding Consultant to Huntingdon Fusion Techniques Ltd, explores the development in the composition of electrodes used in the GTAW (TIG) process. He concludes that refractory oxide doping is beneficial, in particular lanthana and ceria.