In modern times there are plenty of things we use and see every day that are made from metals. But do you know how these metals came to be?
History is interesting to a good many people, but if you’re not one of those people that’s okay! But, this post might not hold your attention well, even though the process is quite fascinating and collecting this information was enjoyable for me that may not be the case for you. This will likely be the only in depth history lesson you’ll find in the blog section of my website.
A bit of background information into the world of molten liquid metal should give you a good idea of how intense the process of creation can be. Metal can be made into many things, it can be of high quality or of low quality depending on the refining methods. Humans have been using this material for thousands of years, as you’ll read in my brief explanation below.
The parent to modern day steel is iron, which scientists and archeologists have discovered remnants of ironware dating back to 1800BC in Anatolia. This information shows that humans have been using some form of iron for thousands of years. [Fun fact: Though we have been using forms of iron since ancient times, copper was used even earlier on in human history].
The base of steel requires iron ore, which is found in sedimentary rocks. Because pure iron is inherently ductile/soft, during the smelting process (heating/melting), the addition of carbon is important for strength.
Early on, the iron making process was done in a “bloomery” which looks like a chimney and made of earth material such as clay or stone. It has one or more tubes (made of clay or metal) at the bottom to introduce air into the furnace and a may have an opening to remove the finished bloom, or some styles may be tipped over to obtain the finished product. The bloomery is preheated with charcoal and when hot enough, small pieces of iron ore and additional charcoal are added in from the top. The temperature and ratio of charcoal must be controlled so that too much carbon is not absorbed into the iron (which would make it too hard to be workable). Small particles of iron and molten slag fall to the bottom to create what is called a bloom. The bloom can later be heated and beaten with a hammer; it is then know as “worked” or “wrought iron”.
Cast iron is made differently, as it has a higher carbon content (making it much harder) Cast iron was first made by the Chinese around around 500-401 BC; where iron ore would be melted and poured into molds to make weaponry, agricultural tools, and statues; since cast iron contained a lot of carbon, it was very hard, but very brittle. Steel was produced by the Chinese (Han Dynasty) between 250BC and 250AD, where they melted together cast iron and wrought iron to create a superior carbon intermediate steel.
In an effort to make higher quality of iron in the use of guns, as the production of steel was expensive (too expensive to make weaponry such as cannons from it). The steel making process was further refined by Henry Bessemer of England (patented in 1855) which made production more affordable, efficient and yielded a better product. His method was to burn off as much of the carbon and impurities as possible, and then re-introduce the right quantities of manganese, carbon and silicon. This process was carried out through the invention of the “Bessemer Converter“.
In modern day, we use mild steel (iron alloyed with usually less than 1% carbon). It’s the most used type of sheet steel today, and it’s used on a wide range of products, including our cars!
All sheet metals start their journey the same way; being melted down into liquid form and mixed with other added materials. From there, they could be poured into rectangular molds to form “ingots” which are pickled in a chemical mixture to be cleaned before being rolled. In modern steel making, ingots are rarely used; the molten material is poured into a form much closer to the final product, such as billets or slabs.
The “ingots” could need to be rolled several times before the desired thickness is achieved; causing the need for an annealing process to reheat the metal (without melting it), which is likely why the process was improved. Typical steel thickness ranges from 1/2″ thick and down to 1/32″ thick, but thicknesses above and below this range are available from certain distributors.
With the process being refined over time, people like Andrew Carnegie’s were able to utilize the material in mass production through the late 1800s; continued use and improvement over time have allowed us to have a reliable product that is readily available in today’s world. If hand crafts can be considered a form of art, then the production of sheet metal gives metalworking “artists” a blank canvas to create whatever they can envision. From amazing feats of engineering complex designs to something as simple as a license plate, we need metal to shape in our world. [It can be fun too!]
It’s easier than ever to order quality material for a shop or individual, while 150 years ago it wasn’t as likely that you could just pick up the phone and get a 24″square piece of titanium sheet stock that was 1/16″ thick and have it delivered within 2 days.
Being a metalworker can be very rewarding; and with the help of the pioneers before us, we can now enjoy the opportunities we have in the industry with the quality that customers deserve.