Published on October 26th, 2015 | by David Bott and Sridhar Seetharaman0
One man’s ceiling is another man’s floor
Historians used to define the progress of mankind by the materials they used to impose their will on the world around them – thus we had a Stone Age, a Bronze Age and an Iron Age. If it hadn’t been for the speed with which processes were implemented and the social changes that both facilitated and came from the events of the late 18th Century and the early 19th Century then it would possibly have been called the Steel Age rather than the Industrial Revolution, for it was steel that made the machines that powered the changes possible.
In those days steel, although significantly better that the other materials, was an undeveloped material. Although its strength and modulus were adequate at the time, its corrosion resistance was not good and its production needed high temperatures and reactive chemicals. Nevertheless, the insatiable appetite of industry for machines made steel the material of the time.
Sadly, from the evidence of the media and even those who fund research, the common view of steel is that it has remained frozen in history – it is a thing of the past, something mankind went through before it could really use science. This is wrong. It is, in fact, the modern science of steel and its manufacture that still makes it a staple of modern industry and a material which offers real opportunities in the future.
Steel is an alloy of iron. In its most recognisable form, the other material is carbon, and from these two elements, it is possible to conjure a wide range of properties. Add in manganese, chromium, nickel, tungsten and many others and it is possible to produce materials properties unrecognisable to it originators. Not only does the chemical composition of steel give it a wide range of properties, it can produced in many thermodynamically stable or kinetically frozen microstructures – although the temperature (and hence the energy costs) of manufacturing do go up to achieve these enhanced properties.
An interesting aspect of the steel making industry is that it is inexorably linked to its customers, for they need to turn the raw form of the steel supplied into artefacts and that requires further processing – often involving more heat, more pressure and more time – which can alter the microstructure – and hence the properties of the steel.
As the first material of the modern age, steel has been the “sitting tenant” as far as the new pretenders are concerned and their marketing campaigns have added to its reputation as an older material, with less of a future. Of those newcomers, Aluminium has also shown its flexibility in alloys and offers lighter weight in many applications, but although Composites offer tailoring of properties at the microstructural level, they suffer from the lack of an industrial process to make them in quantity and at lower prices. All have complicated supply chains, energy intensive processes and their total environmental cost is therefore difficult to pin down.
Steel has three main stages in its production. The first is the production of iron and some alloying. This is where the chemical composition is effectively set. Then comes treatment with pressure and moderate heat to both produce the physical format and develop the microstructure that gives the required properties. Finally most steels have some kind of surface treatment to protect or facilitate future processing. Steel is also the most widely recycled material, with over 60% recycled in 2008. All of these activities have benefited from better understanding and it is increasingly possible to produce industrial quantities of very high performance steels that retain flexible downstream processing options. This is possible thanks to process developments for producing TWIP (Twin Induced Plasticity), TRIP(Transformation induced plasticity) and other grades of Advanced High Strength Steels. Innovations have also been made to produce high strength steels through lean and simple but innovative processing such as flash Bainite which produces relatively leanly alloyed steel with tensile strength up to 2 GPA at the fraction of the cost of conventional processing.
Part of the “business” problem with steel is that it is heavily capital intensive, with all stages of its production requiring large equipment that use large amounts of energy. In integrated plants, much of the gases produced can be used to lower input energy costs, but the combination of large equipment and high running costs discourages many forms of non-strategic investment.
The current challenges facing the UK steelmaking industry are a consequence of several factors, but they mostly come back to a single assumption. That assumption is that we will not need to produce steel in the future. The UK has not invested in steel making in the way that the US, Korea and China have done and so the factories are neither modern in terms of technology nor flexible enough to produce the latest materials – they are therefore stuck competing in the commodity market where others can cut prices and take market share. That steel is a globally traded material, and the UK is unable to respond to market changes means that global players will invest elsewhere. Given that we still consume about 10 million tonnes of steel in our industrial sector, the consequence of recent history means that we are importing about 60% of that – and it is increasing. We can continue with the path we have been on for the past 20-30 years and import all the steel we will need in the future, or we can use the knowledge contained in our materials departments in universities and what remains of the steel companies and build a industry that will underpin our stated goal of maintaining a manufacturing base. There are examples of companies that have, through innovative technology transformed themselves to become competitive. Nucor Steel, through the adaptation of radically innovative process improvement are now one of North Americas largest steel producers. Austria based Voest-Alpine have through research and development managed to stay well ahead of any competition in producing steel-based solutions to automotive customer needs, as opposed to merely selling steel as a feed material. Whatever, we do, it ought to be an evidence-based, thought-through decision rather than the sleepwalking approach it appears to be.