Steel Fabrication in London – History
Steel Fabrication in London – A Brief History
Nearly 22,700 metric tons of steel were used in the construction of the new Wembley stadium. That is just one of the many modern structures in London that used a vast quantity of steel in its construction.
Steel has been used in construction for many years, and in this blog we are going to look at how steel production began and some of the big changes in the industry as it evolved through the years.
Ancient Steel to the 17th Century
Steel was known about in ancient times, but it was very difficult to make and of varying degrees of quality. Many people have heard of the legendary ‘Damascus Steel’, supposedly a superior steel produced around 2,000 years ago, the precise recipe and methods now lost to the mists of time.
This steel was made in such small quantities however that it was only used for tools and weapons. Steel used for construction purposes began much later, around the start of the industrial revolution in Europe.
Pig Iron and Steel Making
Pig iron is a product created from the smelting of iron ore. It is very high in carbon which is ideal for steel making, but it is high in impurities like silica, phosphorus and sulphur. To make strong steel able to be turned into structural steel, the iron must be purified. This process has changed somewhat over the years, but the principle is still the same.
In the 19th century and into the 20th century, open hearth furnaces were used to create steel – which made the product expensive to make and not as pure as modern steel products. The process simply relies on the impurities rising to the top of the molten metal after the addition of flux. It is time intensive and not as effective as modern methods for extracting impurities. This meant that wrought iron was used more often than steel, until steel production became more economic and produced better quality product.
Steel production increased rapidly through the 20th century, with the development of numerous new techniques for the production process. Whilst wrought iron was the metal of choice in construction during the 19th century, steel became commonplace in the 20th century, and eventually wrought iron was completely replaced as a construction material. The height of wrought iron production can be seen in the 1860s, when huge iron clad warships were at their zenith.
Current Steel production
Most current steel foundries use an oxygen furnace to create their steel. This was a process developed in the 1950s which revolutionised the speed and quality of the steel being produced. The pig iron is heated and oxygen blown through the molten liquid to remove impurities, along with various chemicals called fluxes which bind to other impurities and remove them.
The result is a very pure steel product, which can then have other agents added to create variations of the steel – for example, chromium is added to create stainless steel. The steel is poured into moulds to create the shape and size of beams required, but for the final end product used in construction, a supplier like Surrey Steels will receive set lengths of beams which can be cut down to size as required by the customer.
Alloys of Steel
Today steel production is a science, with varying types of steel produced depending on the requirements of the end user. These are called alloys, and their properties vary depending on the types of additives that are included in the recipe. Chromium for example, is added to create stainless steel, whilst nickel is added to create nickel steel.
The kind of steel most commonly used in construction is known as Mild Steel. This has a small amount of carbon present which creates a strong but quite ductile metal, suitable for large construction projects. This is the product you will find at Surrey Steels!