There are a variety of practices in the blacksmith trade that help in producing high-quality materials. One particular practice that many people wonder about is the submersion of welded metal into water.
Blacksmiths put metal in water because water submersion will allow the forger to control the brittleness and overall strength of the metal. This is referred to as “quenching,” and is used by many blacksmiths to decrease the risk of breakage when crafting new pieces.
To understand why this is a vital process, we need to examine it in further detail. The following information in this article will cover a few topics related to this question. I will discuss what the quenching process is, how it stabilizes the metal, and why it is an essential process for blacksmiths to practice.
What Is Quenching?
Quenching is a technique that blacksmiths use after they have treated metal at very high heat. If the workpiece is not brought back to room temperature in a reasonable amount of time, the microstructure of the metal may end up changing. If this occurs, it will affect the level of strength from your weld.
The basic process of quenching is to fully submerge your metal piece into a liquid.
Water is a common quench, however other materials such as oils and compressed air are often used as alternatives. Once this is done, the metal will harden to its hardest possible point.
When this happens, the metal may become brittle, causing it to break easily; this is why in the quenching process, there are two other steps that must be taken, solutionizing and aging.
All together, they are referred to as “precipitation hardening”.
Precipitation Hardening Process
The quenching method actually has three main processes – solutionizing, quenching, and aging – that together create a solvent on the metal, preventing it from being brittle.
The process is as follows:
This is the first step of the precipitation process. This phase is for dissolving the precipitates on the metal and lessening the separation that may be present in the metal alloy.
To do this, the metal is heated and soaked at its solvus temperature, and the alloy will remain until a solid homogeneous solution is developed.
Once this is done, the metal is removed from the heat, to make ready for its next phase.
This is the second phase, mentioned at the outset of this article. After the metal has been removed from the heat, it is immediately placed into a bucket of liquid, typically water.
When this phase occurs, the material cools at such a quickened rate that it creates a supersaturated solid solution – this means that it contains more of the dissolved material than could be dissolved under regular circumstances, thus causing an excess amount of copper elements upon the metal piece.
Because of how rapid the cooling process is, the precipitates do not have time to form on the metal alloy.
As mentioned earlier, this causes the metal to harden to its individual extent, readying it for the third phase.
This is the third and final step to the precipitation-hardening process. Once the metal has been submerged into the liquid, it is time to re-heat the metal, except this time, it is below the solvus temperature.
By heating the metal at said temperature, it enables the atoms in the metal to disperse at shorter distances, meaning that the metal gains a properly diffused layer of precipitate.
This enables the metal alloy to strengthen without the brittleness in its structure, therefore creating a high-quality weld.
If you are considering picking up blacksmithing as a trade or hobby, it is important to familiarize yourself with this process.
By doing so, you will be able to create high quality welded pieces without the risk of breakage at the point of forging.
It is also important to familiarize yourself with the terminology used, in order to further understand why metal requires this precipitation hardening process, based on the science behind metallurgy.
Why Does Metal Require Precipitation Hardening?
As mentioned earlier in this article, the process of precipitation hardening allows your metal piece to be complete without brittleness in its structure.
This is a necessary step, as brittle metal can break as easily as glass. Therefore, in order to ensure a high-quality weld, it is important to put this method into practice.
You may wonder, though, how the process of forging affects the structure of the metal, to the point where it needs to be cured.
In order to truly understand that, we need to look into the science behind metal precipitants, alloy, and solubility.
The Science – Precipitants, Metal Alloy, and Solubility
You may be slightly surprised to learn how much science plays a role in the blacksmith trade.
However, it is a fact that if a blacksmith does not pay attention to the importance of chemistry in the forging process, they run the risk of ruining the structural integrity of their workpiece.
The following is a list of main chemical compounds and properties in metalworking, and how the precipitation process affects their role in hardening metal:
Precipitants are a secondary cause of precipitation, the creation of a solid from a solution.
The dissolving of precipitants during the solutionizing process of welding is what enables the metal to increase its yield strength, which is further discussed below.
The metal alloy is a combination of metal compounds and/or non- metal compounds. For example, steel is a combination of iron (metal) and carbon (non-metal).
When producing metal for commercial use, the compounds are generally melted together, creating the metals used in forging.
So, when the solutionizing step of the precipitation-hardening process comes about, it reduces the separation between the two compounds in the metal, increasing the level of the hardness of the metal.
This is the property in a liquid, gas, or solid that determines its ability to dissolve. The solubility of an element may increase or decrease depending on its temperature.
Most solids and liquids will increase at high temperatures.
Therefore, when metal is heated during the forge welding process, its level of solubility will increase. This forms a solid solution, hardening the metal to its hardest point.
The bottom line – these various properties and compounds are what contribute to increasing the structural hardness of metal during forge welding, enabling it to reach its hardest point physically.
Understanding the chemistry behind the hardening of metal will enable you to further understand why the precipitation hardening process of forging is so essential, so as to prevent your welded piece from breaking.
Blacksmiths place metal in water In order to prevent the heated metal from becoming brittle and breaking.
The metal is put through the precipitation hardening process, which holds three steps – solutionizing, quenching (where the water submersion comes in), and aging.
This process is vital in protecting the structural integrity of your welded piece. The science behind the need for this process can be explained through the process of precipitation, the components of metal alloy, and the process of solubility.
A thorough analysis of the chemistry behind heated metal will help you to gain a better understanding as to why metal requires a solution after being heated.
If you are considering picking up blacksmithing as a trade or hobby, it is important to carefully and thoroughly analyze the inner workings of the precipitation-hardening process as well as its scientific basis.
Doing so will enable you to ensure the quality of your welded metal, as well as to further expand your skills as a blacksmith.
I hope this article was helpful. Good luck with your future projects!
Cheers, tools owners!