Quenching is a traditional Japanese technique used to create a paste on a blade using water, charcoal, clay, and other ingredients. This paste is applied to the blade spine on both sides, mimicking the wavy hamon of nihonto. A thinner slip is placed on the hard edge to help heat transfer. Water quenching is common in traditional Japanese knife making, as it cools the steel more quickly than oil, resulting in higher hardness. The water used is typically at a temperature of around 0°C.
On Japanese-style blades, water quench introduces sori or curvature, which can cause problems when bubbles form. To prevent this, salt is added to the water to keep bubbles smaller. The blade is then immersed in water, with the tip of the blade just immersed in the water.
Traditional European swordsmen perform heat treatment by quenching the entire blade in water or oil. However, Japanese swordsmiths use different heat treatments, such as applying a clay layer to the blade. A soft steel scraper is used to remove the clay mask, and the blade is cleaned and tempered over the remaining hot coals. After coating the blade in wet clay slurry, the swordsmith heats the blade and quenches it in oil or water. This method allows for subtle differences in the sword’s properties due to the presence of clay.
Quenching in water is a traditional Japanese technique that is rarely used in the West due to its harshness and potential for cracking or warping. For a 3/16 thick carburized iron blade, water is used, or warm brine with similar saltiness as sea water.
📹 Forging A Japanese Style Knife With Water Quench
Are samurai swords quenched in water?
The article discusses the process of quenching steel, focusing on the selection of the appropriate quenching agent and method. It highlights the limitations of various quenching agents and their respective cooling capacities. Water has a large cooling capacity at 650-500 degrees, making it easy to harden but still too fast at 300-150 degrees, leading to insufficient toughness and cracking. Oil has a smaller cooling capacity at 300-200 degrees, making it difficult to quench but not as good as water.
To achieve an ideal cooling rate, the sword heated to austenitization is quenched into water, which is then transferred to oil when cooled to 400-300 degrees. This process ensures high hardness martensite while maintaining good toughness, reducing internal stress, and preventing deformation and cracking. The key is to master the time spent in the water, usually less than 1. 5 seconds. For larger blade thicknesses, the water residence time should be increased appropriately, but not more than 1. 5 seconds.
The article also discusses measures to prevent cracking, stating that the reason for blade quenching is not due to shrinkage but rather the tensile stress generated by the blade bending backwards when the blade cools and shrinks. To avoid cracking, the residual temperature of the blade should be used to temper the blade in time. For single-edged knives, the process can be done by immersing the reddish blade in water, allowing the blade to cool to 200 degrees. After a few seconds, the blade should be lifted from the water and the “rainbow” golden area should enter the edge of the blade.
The actual operation process must be fast and efficient, as failure to temper the blade may result in quenching or insufficient toughness. Unfamiliar sword friends can try with iron plates first and then try the sword after seeing clearly to avoid unnecessary losses. The bearing steel processed by this method can be chopped vigorously without crimping or chipping, making the effect satisfactory.
In conclusion, the article emphasizes the importance of selecting the appropriate quenching agent and method for steel quenching, particularly for single-edged swords that are not too long.
Is it better to quench with water or oil?
Quenching in oil vs. water is a process that depends on the desired material outcome. Water is faster and cheaper but typically results in a brittle end product. Oil, on the other hand, is slower but produces a product with moderate hardness and less stress. The choice between the two depends on the type of material, as some materials can only be hardened with water due to irreversible damage caused by oil quenching.
What liquid do you use to quench a blade?
A steel forging process involves a series of steps to create a hardened steel. These include applying a beveling to the blade, using a heat source like a propane torch or mini-forge, using a fireproof quench container, using oil for quenching, using a fireproof regulator block, testing the steel temperature, using tongs or vise-grip pliers, using a fire extinguisher, wearing a face shield and heat-resistant gloves, testing the blade hardness, and using a kitchen oven.
Step 1 involves normalizing the steel to create a uniform state, making it more resilient and easier to work with. This is achieved by using P150-grit sandpaper to dull the blade edge and heat the steel to 1500 to 1600℉ before cooling. It is important to rotate the steel over the flame regularly to avoid problems with the finished product.
Why do samurai wipe their swords?
In films set in feudal Japan, the practice of chiburi, or “cleaning the sword,” is often depicted as a ritualistic act performed by swordsmen after killing an opponent. However, this portrayal deviates from the historical accuracy of the practice, which was not merely a simple swipe that removed all blood. In actuality, the sword must be meticulously wiped with a cloth in order to forestall the formation of rust. The term “chiburi” is a slang pronunciation that is not found in any Japanese dictionary. The Eishin Ryu of Tosa offers further insight into the practice of chiburi.
What liquid is used for quenching?
After soaking a workpiece, it is submerged into a quenching fluid, which can significantly affect its final characteristics. Water is the most efficient quenching media, but it may cause distortion and cracking. Mineral oils are often used when hardness can be sacrificed, but they often oxidize and form sludge, lowering the process’s efficiency. Intermediate rates between water and oil can be achieved with a purpose-formulated quenchant. Inert gases like nitrogen and noble gases can also be used for quenching.
Nitrogen is commonly used at higher atmospheric pressures, while helium has a higher thermal capacity than nitrogen. Argon, on the other hand, requires more energy to move and has a lower thermal capacity. To minimize distortion, long cylindrical workpieces are quenched vertically, flat workpieces are quenched on the edge, and thick sections enter the bath first. The bath is agitated to prevent steam bubbles.
If an iron or steel alloy becomes excessively hard and brittle due to an overabundance of martensite, tempering is performed to increase its toughness. Tempering is usually performed after hardening to reduce excess hardness by heating the metal to a temperature below the critical point and allowing it to cool in still air.
Why do blacksmiths quench in oil and not water?
Oil is a commonly utilized medium for quenching due to its rapid heat transfer without substantial distortion. In contrast, water-based caustic quenchants exhibit an even more expeditious heat transfer but may induce distortion or cracking in certain materials.
What is the best liquid for quenching steel?
Mineral oil quenching agents are highly efficient and cost-effective for oil-hardened and fast quench-rate steels, offering greater cooling capacities and superior cooling capabilities for steel alloys.
Why do blacksmiths quench in oil instead of water?
Oil is a commonly utilized medium for quenching due to its rapid heat transfer without substantial distortion. In contrast, water-based caustic quenchants exhibit an even more expeditious heat transfer but may induce distortion or cracking in certain materials.
Can you quench 1075 in water?
Simple carbon steels are popular with knife makers due to their ease of heat treatment, making it possible to achieve a good result with simple tools. These steels include 1084, 1075, 15N20, and 5160, which are often used in leaf springs. It is important to use known steels rather than random old pieces, as they may have micro-cracks or other issues that might not be visible on the surface.
To harden a simple carbon steel, heat the steel using various methods such as a blow torch, a fire in the ground with a hair dryer, or a gas forge/furnace. The entire blade should be heated to the same temperature, which can be seen by its color all the way. This method is aimed at someone starting out and will work well with 1084 high carbon steel and other simple carbon steels mentioned. Even better is a gas forge with a thermocouple for temperature control.
Do not rely on the color of the steel as a thermometer, as different light can easily adjust the visible color from time to time. It is simpler to get a magnet from an old speaker and touch the blade to the magnet. When simple carbon steels like 1084/1075 etc are at “Critical temperature”, they are no longer magnetic.
When quenching simple carbon steels, note the colour as this is what you are going for. In with the blade, get it to the same temperature or slightly higher, then QUICKLY get it into the oil. You have little time between the heat source and the oil, as the blade loses temperature in the air quickly. Pre-heat the oil to 30-40 C by heating a piece of steel and stirring around in the oil. This is easy to overdo, but takes a long time to cool down again.
Simple carbon steels are “oil quenched” so do not use water, as it is unnecessarily agressive and might crack the blade. Heating the oil makes it more fluid and thin, allowing it to get close to the blade and cool it quicker. As opposed to thicker, slow-running cold oil, which might create a steam envelope around the blade (not cooling it as quick).
Normalizing simple carbon steels before quenching is essential to reduce the risk of a coarse steel structure and possible bends. To do this, require temperature control, hold the blade at 875 C, let it air cool to black, then heat it again to 875 C for a total of 3 times, then go on to heating it to 815 C and quenching in warm oil.
After quenching, treat the blade carefully by wiping the oil off and having fine sand paper ready. Sand the flats until shiny areas are formed for observing tempering colours later. If the blade comes out of the quench, it is fragile. Wipe the oil off and have fine sand paper ready.
Place the blade in the stove at 200 C, pre-heated, for 2 hours, cool it under the tap, and inspect the tempering colors. Anything from light straw to dark bronze is generally considered ok. Tempering colors are oxide building up on the steel, and some clever people have tested this repeatedly to show clear “rules” for what color is showing based on the temperature.
Canola oil is a good option for tempering simple carbon steels, as it is thin enough to quench quickly, cheap and readily available, does not contain dangerous substances, and is easy to remove when needed. Higher tempering temperatures affect the final hardness of your knife blade. For a sword, accept giving up some hardness and temper at a higher temperature than for a chef or outdoor knife.
Why is quenching in water bad?
Plain water is a common quenchant for low hardenability steels due to its high quenching power and low boiling temperature. However, its rapid cooling rate can cause distortion or cracking in the lower temperature range. Water’s thermal conductivity is small compared to most metals, and its vapor blanket stage may be prolonged, especially at elevated temperatures. This stable phase encourages vapor entrapment, leading to uneven hardness and unfavorable stress distribution.
Water quenched steel parts may rust unless treated with a rust preventive, making it restricted to simple, symmetrical parts. The maximum heat transfer occurs at low temperatures, potentially causing distortion or cracking.
Can I clean katana with water?
It is inadvisable to use water to maintain your Katan, as it can cause corrosion and the formation of rust. Google provides and maintains a variety of services, including the tracking of outages, the protection of users against spam, fraud, and abuse, the measurement of audience engagement, and the use of cookies and data to inform the development of new services. Furthermore, they assess the efficacy of advertisements and present tailored content in accordance with user preferences.
📹 Quenching a Katana
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I’ve considered trying a mild steel san mai a few different times and just never brought myself to do it yet but I think that might be a project in the near future. For the core steel is it necessary to have a pretty high carbon steel core like what you used or would anything from 5160 and up work well?
Yes, very successful! The water quench and cold forging takes some bravery thats for sure, especially considering how super thin you got it down to. I put Erick (Rivers experience) onto some quenchant you might want to look at as well, the Houghton’s Aqua-Quench as you can dial in the speeds of the quench depending on the ratio of water to additive ratio. It’s pretty important when you’re working with the nearly-pure carbon steels without a lot of manganese in them for deeper hardening. Even the really very fast oils sometimes can’t go fast enough and you end up in a tricky spot of using water and risking cracking
Frankly i disagree that san-mai blades were made to combine toughness and hardness. In my experience, an iron core and steel edge makes a knife that behaves like a crap steel plate that cuts. Mild steel is not “tough”, yes you can bend it on itself and it’s not gonna break, you can even make a knot with bars of steel, but compared to tempered steel it’s pretty damn disappointing. If you want a tough material, you can quench and then blue temper the back of your blade. Blue tempered steel IS tough, much more than mild steel. Don’t forget at the time making steel was an extra step, and was costly. They used as much crappy cheap steel because they could, and it saved material and money. It’s not about performance.