2023-10-10 21:26:49
We live in a world of steel. It is so common that we use it as a metaphor for everyday life. There are those who have nerves of steel, and it is ship steel the biceps of so many muscular young men. What is not a metaphor is that steel is everywhere we look: in food containers, in jewelry, in buildings, refrigerators, railways, roads, surgical implantsthe cars, the shopping cart, the baby’s crib, the strings of a piano…
The steel is the second most consumed raw material globally after oil (Steel alone makes up 99% of the world’s metal consumption!). And it is also, attention, the metallic material that is recycled the most: 100% of steel can be recycled and 90% of the steel consumed is recycled. Iron ore, the main raw material for its manufacture, is abundant and, furthermore, its handling is not dangerous for humans.
On the other hand, we are faced with a cheap material to produce that can be molded, forged, welded… It is resistant, easy to manufacture and light, if we consider its specific resistance (resistance divided by density). If the Eiffel Tower were built again with steel instead of iron, it would be between 3 and 4 times lighter than the current one.
Within a hundred years, many of the fashionable materials and alloys that are most researched today will have ceased to be used due to their criticality, their unhealthiness, their strategic value or their scarcity. But steel will continue to be essential.
So why isn’t it investigated more? Is it banned?
Nobody remembers the steel
If you ask twenty experts to list ten new materials, or ten advanced materials, it is difficult for them to remember steel. If we look at the contents of ten master’s degrees on new materials or advanced materials, we will not find steel in the program either. And what is worse, if we scrutinize any competitive call for Materials Science and Engineering projects, we will hardly find the steel category among the priority lines for financing.
However, there is no structural material that influences us more as a society, in general, and as a technological society in particular. There is no structural material on which so-called new technologies depend more than steel. And steel is also one of the materials that most affects, in different ways, the so-called energy transition.
The benefits of perlite
Steel is an alloy based on iron and carbon, along with other alloying elements. Its microstructure is governed by a reaction called eutectoide which gives rise, in most cases, to an ideal material that is known by perlite. Perlite could be considered the perfect composite material, if it were not for the fact that it is not really a composite material.
Pearlite is made up of alternating sheets of iron (ductile and soft) and iron carbide (brittle and hard), so closely united and in such a perfect relationship that the result is a very resistant material with acceptable ductility.
This microstructure of the steel can be modified with thousands of possible heat treatments that offer benefits that cover thousands of possible combinations between resistance/hardness and ductility. In fact, there is no other alloy family as versatile.
And to top off the goodness of this material, all the manufacturing, shaping and heat treatments processes are, possibly, the most reliable and reproducible of all the alloys that exist.
The Achilles heel of steel: the generation of CO₂
Primary steel is obtained from the reduction of iron ore in the form of oxides in blast furnaces.
This is the Achilles heel of steel, since huge amounts of CO₂ are generated in this process. Is he second industrial process, after cement manufacturing, capable of generating CO₂. And in a world locked in the quest for zero emissions, this is a problem. That is a problem with a solution, because steel can be manufactured without emitting CO₂, replacing the material necessary for reduction, carbon (normally in the form of coke) with hydrogen.
Given that we need steel in all so-called alternative energy production, it is urgent to increase R&D in primary steel production processes, also alternative. And let’s not forget that steel is the alloy that is recycled the most, so a large part of the steel consumed is “secondary”, that is, it comes from recycling.
There is no material, no alloy, that engineers or scientists know more about. We know all its interiorities. All simulation tools (starting with thermodynamic simulation), design and development tools began using steel as the material under study. Heat treatments of steel are the reference for the study of any other alloy. Materials Science is based on the physical metallurgy of steel. One of the first phase diagrams studied was the Fe-C diagramand it is undoubtedly the most used diagram.
Our society needs R&D investment in steel
Today, and in the coming decades, steel is and will be part of our lives, and we need to have the best steel possible.
Let’s return steel to the front line of investment in R&D. Whether we like it or not, we are still in the Iron Age, and steel can still surprise us just as it did 40 centuries ago, when the Egyptian armies were amazed by a new material that the Hittites used which cut their bronze swords and shields like butter and gave them victory in battle.
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