Heat Treating Step-by-Step
- 1 Heat the Blade. Start the forge and use the tongs to place the knife inside. Only the blade section of the knife needs...
- 2 Judging Color. Dim lighting is helpful in judging the color of the blade as it heats. The goal is to attain an orange...
- 3 Critical Temperature – The Magnet Test. Touch the knife to the magnet. If the knife sticks, the...
Full Answer
How do you know what temperature to heat treat a knife?
As you are heating it up, watch the color of the steel. After you have heat treated a few knives, you will be able to tell roughly what temperature the steel is based on the color. Until then, you'll just have to trust me; 1500 degrees (what you are aiming for), is a cherry red color which comes just after the metal first starts to glow.
Does heat treatment really affect knife performance?
However, it has become somewhat fashionable to talk about knife performance as entirely (or almost entirely) controlled by the knifemaker’s skill in heat treatment. This has some truth to it as knifemakers who use a subpar heat treatment will certainly have subpar performance. However, the heat treatment can only do so much.
Do I need to quench my knife after heat treatment?
For certain quenchants and certain steels, an interrupted quench can be beneficial, but for this heat treat it isn't necessary and if anything, could make your steel softer. Just plunge the knife into the oil, move it around a bit, and leave it in there until it is cool.
What to do with old heat treated knives?
If the knife is a collector or show piece, put a coat of Renaissance wax and enjoy the view. Heat treat won't matter much If the knife is a user, you'll pretty quick if it was heat treated appropriately for your use.
How do you test for heat treatment?
Heat treatment verification methodsX-ray diffraction. The X-ray diffraction method enables measuring the absolute residual stress value and retained austenite content. ... Barkhausen noise analysis. ... Stresstech provides turnkey solutions for heat treatment verification and retained austenite measurements.
What temperature do you heat treat a knife?
This process, known as tempering, can be done over a fire or using a blowtorch, but the simplest method is to put it in your oven at 400℉ for two one-hour cycles, letting the knife cool between each one.
Can you temper a blade too much?
While you can definitely over-temper a blade, that will leave it too soft rather than too brittle; you can also over-harden (or, rather, under-temper) it, which will leave it very hard and very brittle.
How thick should a heat treat knife be?
Well-Known Member. . 030-. 040" thick before heat treat, this also helps to prevent the edge from warping and cracking, and leaves plenty of thickness to clean up.
What can go wrong during heat treatment?
MOST OF THE PROBLEMS in heat- treated parts are attributed to faulty heat- treatment practices (such as overheating and burning, and nonuniform heating and quench- ing), deficiency in the grade of steels used, part defect, improper grinding, and/or poor part design.
Can metal be heat treated twice?
Twice-tempering is simply a process whereby the steel is heated and then cooled twice in succession, not necessarily at the same temperature each time.
Do you quench after tempering?
Tempering is most often performed on steel that has been heated above its upper critical (A3) temperature and then quickly cooled, in a process called quenching, using methods such as immersing the hot steel in water, oil, or forced-air.
What oil do you use to quench a blade?
There are many food-grade quenching oil options available to use for blacksmithing. Among these options are vegetable, peanut, and avocado oil. Some commonly used vegetable oils are canola, olive, and palm kernel oil. Vegetable oil is very cheap and comes from renewable sources.
Can you temper a knife with a torch?
0:577:17Tempering File Knife With Torch . - YouTubeYouTubeStart of suggested clipEnd of suggested clipYou know stays wet stays cool and it doesn't harden and it only it only softens the areas that I hitMoreYou know stays wet stays cool and it doesn't harden and it only it only softens the areas that I hit with the torch.
How thick should Edge be before heat treat?
The following grind stock should be left on the edge of the blades: Air hard edge thickness: 0.015” minimum. Oil hard edge thickness: 0.030” minimum.
What is Peters Heat Treat?
Peters' Heat Treating provides services for the custom knife maker. Turnaround time is currently four weeks (from receipt of your order to when we return ship it). Christmas orders must be received prior to Thanksgiving in order to assure receipt prior to the Christmas holiday. We heat treat ALL grades of steel.
Why heat treat a knife?
The purpose of heat treating a knife is to harden the steel sufficiently for use. The correct degree of hardness will depend on the blade’s intended purpose. It needs to be hard enough to maintain its edge yet flexible enough to endure regular and sometimes intense use. At Red Label Abrasives, we take pride in providing knifemakers with ...
What is the process of heat treating knives?
Heat treating is a part of the knife making process that is designed to help harden the steel of the blade for use . Heat treating can be accomplished in four steps: normalize, quench, temper, and sand.
What can I use to quench a knife blade?
You can use metal coffee cans, a cookie tin, or something similar. Oil for quenching.
How long does it take for a forge to harden?
For the blade to harden, it needs to cool below 900℉. Wait about 10 to 15 seconds before pulling the blade out and checking it for warping.
What grit sandpaper should I use for a forging blade?
The forging process in particular causes the carbides to bunch up and become oversized, which can prevent it from properly holding an edge. Use a sheet of P150-gri t sandpaper to dull the blade edge and minimize the possibility of warping or cracking during treatment.
How to prevent air bubbles in steel?
After heating, quickly plunge the steel into a can of oil and move it back and forth in a slicing motion. This helps to prevent air bubbles from forming around the steel. Then lay it on the regulator block, which should be submerged in the oil. (The block ensures that both sides of the blade are evenly cooled.)
How to soften steel?
To soften the steel and relieve built-up stresses, you need to immediately heat it up again - this time to 400℉. This process, known as tempering, can be done over a fire or using a blowtorch, but the simplest method is to put it in your oven at 400℉ for two one-hour cycles, letting the knife cool between each one.
How to get a knife to critical temperature?
When you are satisfied you have got the blade to critical temperature, you need to move fast. You don't want to lose too much heat. Quickly move the knife out and plunge it into the oil. I generally agitate it back and forth inside the oil, to break up any air bubbles that may have caught in there and make sure that blade is cooling evenly. In the video you can see me pulling the knife out of the oil and putting it back in several times. That is called an interrupted quench. Don't do that. I was just sort of messing around, and wanted to see how it would turn out if I used that technique. For certain quenchants and certain steels, an interrupted quench can be beneficial, but for this heat treat it isn't necessary and if anything, could make your steel softer. Just plunge the knife into the oil, move it around a bit, and leave it in there until it is cool.
How to test if a knife has hardened?
To test the steel and see if has hardened correctly, take a file and scrape the corner of the file across the knife. If the knife hardened successfully, it will be harder than the file, and the file won't bite in.
Why is heat treating important?
Heat treating is undoubtedly the most important part of knife making. It alone is what determines whether or not your knife will hold up under abuse, shatter when dropped, or bend like a pretzel when hacking on an unusually rebellious piece of wood. Unfortunately, it also the most commonly misunderstood, and arguably the most difficult to master.
How hot should I heat oil for welding?
Get your oil in your heat resistant container, and pre-heat it to about 130 degrees (Fahrenheit).
How long to soak in heat treating oil?
There are those who want you to believe the only way to achieve a good heat treat is by using a temperature regulated heat treating oven, soaking for 15.7 minutes, normalized 2.3 times, and then quenched in park's knife heat treating oil raised to exactly 134.6 degrees Fahrenheit.
Is heat treating a science?
Now don't get me wrong, heat treating is a science, and with delicate temperature controlling equipment, you do get a better heat treat. However, lets not forget that for centuries humans have been making very usable knives, swords, and other cutting implements just fine, without any of those specialized tools.
Is steel hard to quench?
After quenching, the steel is extremely hard. So hard that it is about as brittle as glass. If you were to drop it or subject it to any amount of force at this point, it would be liable to shatter or crack. In other words, it is way too hard to be a knife.
Who published the Heat Treating Data eBook?
But, if you are looking for more detailed information, on these processes as well as the terminology associated with them, please refer to this guide: The Heat-Treating Data eBook published by the SECO/WARICK Corporation.
How long should you temper steel?
If you drop it now, it will shatter. You want to temper it as soon as it gets to room temperature. Temper twice at 2 hours each allowing the steel to cool back to room temperature between cycles.
Why normalize steel?
Normalizing steel allows the crystalline structure to be reset and resets the carbides back to uniformity. Steel doesn’t like uneven structure. If the carbides have gotten all bunched up and oversized from forging, the steel won’t hold an edge as it potentially could. Bar stock from the mill probably shouldn’t have to be normalized, especially if it has been annealed. Material that has been forged could probably benefit. Basically, heat it in your forge or oven and let it air cool. Done.
How to get fire started with hot steel?
Moving a blazing hot piece of steel from heat to oil is where a lot of fires get started. Knock over the oil, drop the red hot steel into the oil and instant fire! So, be careful! The steel will retain heat and survive a few seconds in the air as you move from heat to quench.
How long does it take for steel to cool off?
Most agree that the steel really needs to be cooled off at a high rate, like 1 to 2 seconds and, that is absolutely true. However, that doesn’t mean you only have 1 second to get from your heat source to your quench. Moving a blazing hot piece of steel from heat to oil is where a lot of fires get started.
Can you put acetone in dry ice?
Some people add acetone to the dry ice. Acetone is crazy flammable, and it would not be a recommendation. Use Kerosene or even diesel fuel if you feel you need a liquid medium but, just putting your blade under a block of dry ice is sufficient.
Can you use canola oil for quench?
Quenching oil is very sophisticated in design and application. If you can’t afford it, use low viscosity motor oil or even canola, vegetable or peanut oil. It won’t be perfect but, it will work. Veteran knife makers will tell you to use dedicated heat treat quench oil to get better results.
