Use a sheet of P150-grit sandpaper to dull the blade edge and minimize the possibility of warping or cracking during treatment. Then use the heat source to heat the steel to 1500 to 1600℉ before allowing it to cool. Be sure to rotate it regularly over the flame: concentrating on one side can cause problems with the finished product.
Full Answer
How to stop a quench from warping the blade?
Pull the blade from the quench after about 8-10 seconds. If it flares up or smokes heavily put it back in immediately for a few more seconds, but if it simply wisps a little smoke you have a good interrupted quench that will slow things down as you start Ms that will reduce warping and wavy edge.
How do you harden a steel blade?
Before you harden give it a 1200F stress relief temper.The 'ground very thin " can cause problems and many start thicker and do final grinding after HT. Agitate the steel in the oil during the quench, this reduces vapor pockets and gives a more even quench. Pull the blade from the quench after about 8-10 seconds.
How do I Stop my Steel from warping?
If it flares up or smokes heavily put it back in immediately for a few more seconds, but if it simply wisps a little smoke you have a good interrupted quench that will slow things down as you start Ms that will reduce warping and wavy edge. The steel will be dead soft and malleable on the way down at 500F.
How do I quench the steel in the oil?
Agitate the steel in the oil during the quench, this reduces vapor pockets and gives a more even quench. Pull the blade from the quench after about 8-10 seconds.
Why do knives warp when quenched?
When these heated parts are quenched, their internal crystal structure changes again, and that volume change is not necessarily sufficient to offset the change upon heating. This change of volume can cause dimensional distortion.
How can you reduce distortion in heat treatment?
Press quenching is a specialized quenching technique that can be used to minimize the distortion of complex geometrical components during heat treatment.
What causes distortion in heat treatment?
Causes for Distortion – General Holes, slots or varying section on a part (These areas will quench faster causing differential part cooling.) Part too long, high length/diameter ratio (As a rule, a ratio over eight-to-one results in distortion.)
How do you prevent heat treatment scaling?
To prevent scaling and decarburization, care is taken to apply a uniform coating layer on the component. The coating also reduces decarburization on billets and ingots during hot-forging and hot-rolling operations. Heat transfer from the heating medium to the metal is unaffected by the coating.
In which quenching medium the chances of distortion is minimum?
Gas or air quenching will provide the least distortion and may be used if the steel has sufficient hardenability to provide the desired properties.
What is warpage in heat treatment?
Shape Distortion (warpage) as a result of heat treatment is a result of processing or design issues rather than the expected phase changes of the material. Rapid heating can cause stresses to develop in parts because of excessive temperature gradients.
Which heat treatment process is most susceptible to creating distortion problems?
Quenching is perhaps the area in a heat-treat operation where the problem of distortion will occur.
How will a metal distort when heated?
When a weld is laid it is molten metal and therefore hot, as it cools it shrinks, this shrinkage imposes stress on the weld and the parent material near the weld. Distortion is also created by localised heating of the base metals which causes local expansion and contractions during the welding operation.
Which should be added in alloy steel to remove distortion in quenching?
Slow (15-20 second) oils are used where hardenability of steel is high enough to compensate for the slow cooling aspects of this medium. All of these oils are used when quenching carburized and carbonitrided parts.
How do you prevent steel Decarburization?
Decarburisation can be prevented by heat treatment in an intert atmosphere, by wrapping the component in stainless steel foil, or by painting with an isolating paint.
What are the five basic heat treatment process?
There are five basic heat treating processes: hardening, case hardening, annealing, normalizing, and tempering. Although each of these processes bring about different results in metal, all of them involve three basic steps: heating, soaking, and cooling. Heating is the first step in a heat-treating process.
What is scaling during heat treatment?
Scale —the dark brown- or black-colored flaky material often observed on the surface of a part when exposed to high heat— is more than just unsightly. Often, parts require additional machining after they're heat treated, and if heat treat scale isn't removed, it can flake off during machining.
What temperature should I use for a knife?
In our knife making world the recommended hardening temperature can vary from 780ºc to 1100ºc so you can see that magnetism is only a guide that you’re getting there, not a firm indicator that you’re at the correct hardening temperature.
What temperature does stainless steel harden at?
However, a word of warning. Stainless Steels are extremely sensitive to hardening temperature. Literally, a 20ºc – 30ºc variation from the ideal hardening temperature can severely compromise the properties obtained.
What is decarburization of steel?
If the carbon is removed the steel won’t harden as carbon is the primary alloying element that turns iron into steel.
How to normalize steel?
To normalise any steel heat it to 30ºc above the hardening temperature (if a hardening range is given use 30ºc above the top of that range) and let it air cool to room temp. Time at temperature need only be the same as for hardening. It is important that it then be allowed to cool to the point you can handle it. (If you’re normalising pattern welded steel use the higher of the temperatures as may be recommended for any of the different constituents.)
What is normalising steel?
Normalising is the process used to ‘normalise’ a deformed microstructure, e.g. after forging. Normalising is similar to annealing except that after heating the steel is usually air cooled and it doesn’t matter if it hardens slightly (or even fully).
Can you freeze carbon steel knives?
Sub-Zero treatments are for Stainless Steel blades only. There’s no substantial benefit to carbon steel knives. They are intended to remove retained austenite and if trying to achieve absolute maximum hardness one needs to har den from the very highest recommended temp, and freeze to -90ºC or below to remove most of the retained austenite. However, this will only give an extra 1-2 points Rockwell hardness as well as increasing the brittleness of the knife.
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.
