Many modern industrial metal fabrication practices model their blacksmithing and metal forging techniques from the medieval and ancient world. Aspects of the smelting, forging, metal property manipulation and the use of alloy materials all got their start as primitive practices rooted in pre-industrial civilizations across the globe.
It’s because of this past that metal fabrication is what it is today. When we look back at the past, it’s easy to see the logistical processes used to evolve and progress the art of metal manipulation.
While the technological resources and capabilities of metal fabrication and manipulation have experienced immense leaps and bounds forward, there are still basic elemental practices that the industry owes its prosperity to. Fabricators and manufacturers should constantly strive to pay homage to these ancient techniques that have paved the way for modern metal fabrication practices and knowledge.
Metal Manipulation 101
The manipulation of metals was unearthed globally during the approximate timeframe of 3300-600 BC, forming what’s commonly referred to now as the Bronze Age.
Following the Stone Age chronologically, Bronze Age metal fabricators and traders were known to have mined and smelted lead and copper, alloying with tin, arsenic and other metals to create bronze, an alloy material which offered increased strength and value. It’s through this early process of smelting, alloying, and forging that helped accelerate global human culture in various regions across Europe, Asia, and Africa.
During this timeframe, lead and tin were the first metals to be smelted. Lead casts have been found in modern-day Turkey from about 6500 BC – while their production remains a mystery, as the invention of writing came later, leaving the process shrouded in speculation.
Typically, lead was melted in campfires, having little impact on the ancient world. It was used as mortar, a pliable metal for water containment and for piping in ancient Greece and Rome. Copper came next, and with it the kiln, because of the temperatures required to melt the metal.
The process of smelting is a form of extractive metallurgy, meaning its main use is to separate a base metal from its ore. Still used in metal production today, traditional smelting required a heat source and a chemical reducing agent to decompose the ore, usually a source of carbon like charcoal or coke. This carbon element removes oxygen from the ore, leaving behind the metal itself. As most ores are impure, a flux, or chemical cleaning agent, like limestone is used to remove slag from the ore as well.
This chemical reaction combines the oxidizing materials to free the metal from the ore.
Copper pottery kilns used as primitive smelters were first used around 5000 BC, as campfires used to melt and soften lead were about 200°C lower than required to melt copper.
By combining molten copper with tin or arsenic to make bronze, ancient blacksmiths and metal manipulators could increase the strength of the copper and were used to make weapons, shields and body armor, as well as tools like chisels, saws, pots, cauldrons, and sewing needles.
Iron smelting dates back to about 900 BC and early Roman times. Iron smelting in ancient Egypt and western Africa could have accidentally discovered properties similar to carbon steel through complex preheating methods. This meant being able to control a heat source of about 3,650 degrees Fahrenheit to cause the iron ore to melt into a liquid that would flow easily.
Most early iron smelting processes meant the use of a bloomery or a low prolonged heat that would not melt the metal, only soften until it could be pounded with a hammer. The bloomery was replaced by a blast furnace, a further tool in the process to create workable bar iron.
Main heat treatment techniques are separated into four distinct practices:
– Case Hardening
Hardening is when a metal is heated to a cherry red and plunged into cold water, quenching the metal. Plunging the metal into the water straight ensures minimal distortion. If brittleness or distortion continues to be an issue, adding salt or oil to the water increase the boiling point, slowing down the cooling process.
Annealing is the heating of a metal to a cherry red color, and then allowing it to cool slowly. The primary purpose of annealing is to alter the chemical properties of the metal to increase its malleability and to reduce its hardness so that it becomes more workable for shaping, stamping and forming.
Tempering is used to put a good hard edge on a piece of metal, enabling the tool or piece to take quite a beating. It involves the polishing of the face of the metal until you achieve a shine, then slowly reheating the piece increasing the heat where strength is required. The polished portion causes the metal to change color, with peacock, being the ideal tempered hardness. Tempering can be repeated again and again to increase strength.
Case hardening is a seldom used carbon-increasing method, wherein prolonged exposure to heat (for upwards of 10 hours) is joined by packing the piece into a powdered charcoal or carbon-rich substance. Hardening must be completed afterward.
These metal treatments to increase strength have been used over time to create metals designed to serve different purposes. Depending on their intended usage, they may require one or more of these practices, just as certain gauges and strengths of steel or other metal may be required of a modern day fabrication company for modular or structural use. For example, modular construction requires stronger welds because the pieces are transported fully or partially assembled. Metals for these uses may benefit from being tempered and hardened, depending on a multitude of factors.
Use of Alloys
An alloy is a mixture of metal and another element. Characterized as a metal bonding character, an alloy can be made from a solution of solid elements or a mixture of metallic phases. Used in a variety of applications in modern times, alloys were used in ancient times to bring forth practical characteristics in metals.
Examples of alloys are most commonly steel, aluminum alloy (bonded with copper, magnesium, manganese, silicon, tin or zinc), solder, brass, pewter, bronze, and amalgams.
Alloys were used traditionally in strengthening, lightening and increasing the workability of certain metals for certain applications. For example: steel, an alloy consisting of iron and other elements like carbon, was widely used in plating and weaponry upon its invention around 1800 BC.
Nowadays, the use of alloys is much the same. One particularly popular modern iteration of an alloy exploration is in Ford vehicles, which have opted to use aluminum alloys – blended with magnesium and silicon, as well as high-strength steel where applicable to increase strength and decrease weight in pickup trucks.
Forging / Welding
Combining two pieces of metal, whether through modern welding or traditional forge-welding, has been a staple of fabrication and metal manipulation for millennia.
The most typical ancient method for joining metals together is through heating and hammering them manually. Known as forge-welding, the joints can be achieved in a number of ways, notably via a Lap Scarf Weld, or a Vee weld, wherein ends are crafted and prepped for hammering.
Welding can be broken into two arenas: fusion and diffusion welding. Fusion is common in the gas or electric welding of today, while diffusion relies on joining the metals without melting them in a solid state. In ancient and medieval times, forge welding was used to create everything from farming implements to weaponry, gates and prison cells.
Forge welding is still practiced today, usually through a mechanized process involving a heated press, which presses overlapping metals together, creating a weld. Modern steel pipe is often forge-welded during the manufacturing process using a specially shaped roller to continually press and shape the welds or joints into a continuous seam. Many alloys and modern materials can be forge-welded, like carbon steel and even aluminum alloy. Titanium is commonly forge-welded because of its ability to create a strong weld when in a molten, solid state, rather than when the metal is liquefied.
What the Future Holds
From investigating the past, we can see that metal manipulation through blacksmithing, smelting, the advent and use of alloys, and welding/forging practices have maintained constant progress since their inception hundreds, if not thousands, of years ago.
If anything, we can accurately predict that these elemental practices will only increase in their usage, strength, and practicality over time. We can expect to unearth and hone new alloy materials by combining different combinations of metals and other elements; we can expect to see the continued development of welding processes which increase the mobility, and strength of metals. We can also be sure to see the reimagined use of metals in new applications.
What is interesting is that all of these processes, while new and advanced in scope, all harken back to some form of ancient knowledge that put humankind on the path of advancement like never before. It is this realization, that respect should be given to our ancestors for unearthing these basic principles, and for passing them along for us to use, adapt, modify and refine.
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