Heat Treat with a torch?

Yes and no. It really depends on the steel. A simple steel like 1084 will likely heat treat just fine. There are many experienced smiths who use a torch and differentially heat treat blades (just heat the edge with the torch to temp and then quench). That's why 1084 is such a great beginner's steel. It can be heat treated with a minimum of expensive equipment and get satisfactory results.

Other common steels like O-1 and any stainless steel need more temperature control and longer time at temperature (i.e. you need a heat treating oven or a well controlled forge). O-1 does well with 15-20 minutes of soak time, and stainless steels often need 45 minutes at temperature. This is all but impossible to do with a torch without overheating/underheating. Tempsticks are great to tell you when you reach the target temperature, but won't really help you hold it there. With steels like 1084, that's not a problem because you don't really need any soak.

--nathan
 
silver_pilate said:
Yes and no. It really depends on the steel. A simple steel like 1084 will likely heat treat just fine. There are many experienced smiths who use a torch and differentially heat treat blades (just heat the edge with the torch to temp and then quench). That's why 1084 is such a great beginner's steel. It can be heat treated with a minimum of expensive equipment and get satisfactory results.

Other common steels like O-1 and any stainless steel need more temperature control and longer time at temperature (i.e. you need a heat treating oven or a well controlled forge). O-1 does well with 15-20 minutes of soak time, and stainless steels often need 45 minutes at temperature. This is all but impossible to do with a torch without overheating/underheating. Tempsticks are great to tell you when you reach the target temperature, but won't really help you hold it there. With steels like 1084, that's not a problem because you don't really need any soak.

--nathan
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So with a steel like 1084 once you get it up to the proper temp you can quench it? I have never attempted making a knife but am getting the itch. I have the facilties at work such as drill press, vises, belt sanders, torches, oils I would need for quenching and so forth.
 
52100 and 5160 are good steels to heat with a tourch. Ed fowler and Bill Burke are two that come to mine.
 
I have made 8 knives total, 6 out of 1084. All have been HT'd with two torches. I set up the two torches a few inches apart, so that the second torch helps heat the other half of the blade, and it's much easier and quicker to reach the temp. Then heat until it reaches non-magnetic and then you're ready to quench. It's not perfect, and I know it's not as hard compared to a controlled temperature, but it got the blades hard enough to skate a file, which was fine for me in my beginning stages.

By the way, I quenched it in about 150 degree canola oil.

Phillip Patton tested the spine of one of my knives in hardness, and it came out to be 38, which is not hard for a knife, but the edge of it was hard enough to skate a file before tempering (Didn't test the edge to prevent the blade from cracking).
 
MIKE, raise your quench temp one or two shades redder than non-magnetic, drop your oil heat to around 130°, and it will get harder. Temper around 425° to 450°.
 
go mike said:
I have made 8 knives total, 6 out of 1084. All have been HT'd with two torches. I set up the two torches a few inches apart, so that the second torch helps heat the other half of the blade, and it's much easier and quicker to reach the temp. Then heat until it reaches non-magnetic and then you're ready to quench. It's not perfect, and I know it's not as hard compared to a controlled temperature, but it got the blades hard enough to skate a file, which was fine for me in my beginning stages.

By the way, I quenched it in about 150 degree canola oil.

Phillip Patton tested the spine of one of my knives in hardness, and it came out to be 38, which is not hard for a knife, but the edge of it was hard enough to skate a file before tempering (Didn't test the edge to prevent the blade from cracking).
Click to expand...

Would something similar work for 52100? I want to do some small knives in 52100, can you go through the process in detail? All I have is a torch, some canola oil, and some liquid nitrogen. I'm aiming for a hardness just a bit below the given steel's maximum hardness.
 
Mike's temps are a bit off, but the principle is about right.

I am not a fan of torch HT, but for simple steels, it will work. 1070,1080,1084, 5160, and 52100 will all quench sufficiently to harden with a torch. Of those, I would say 52100 is the most problematic. It is a 1% carbon steel ( hyper-eutectoid) with 1-2% chromium. It has to be heated to 1550F to austenitize. Then quenched in 120-130F oil ( canola is good enough). It has 3 seconds to cool down past 1000F ( the pearlite nose). Once cooled to room temperature, temper at 450F for two hours,cool and repeat temper. If doing a cryo in LN, do a snap temper at 300F for an hour before the cryo.Temper at 400-450F after cryo.

Stacy
 
If you don't have an oven/forge then you gotta go with what you have. A torch isn't the worst thing you can do. Atleast you will avoid warpage. However, everything I've learnt about bladesmithing tells me that a full quench resulting in a homogenous hunk o steel is a good start. You can select temper the spine back later if that is what you desire.

Rick
 
i have been using a torch for years on 1075 and it works great for me. i experimented with the steel i was using to find out what worked the best before making my first blade. i quench in used canola oil or a mix of motor oil and transmission fluid.
 
bladsmth said:
Mike's temps are a bit off, but the principle is about right.

I am not a fan of torch HT, but for simple steels, it will work. 1070,1080,1084, 5160, and 52100 will all quench sufficiently to harden with a torch. Of those, I would say 52100 is the most problematic. It is a 1% carbon steel ( hyper-eutectoid) with 1-2% chromium. It has to be heated to 1550F to austenitize. Then quenched in 120-130F oil ( canola is good enough). It has 3 seconds to cool down past 1000F ( the pearlite nose). Once cooled to room temperature, temper at 450F for two hours,cool and repeat temper. If doing a cryo in LN, do a snap temper at 300F for an hour before the cryo.Temper at 400-450F after cryo.

Stacy
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So I would oil quench the 52100 blade after heating to where it's no longer magnetic?

During the tempering, is there a specific color I should look for on the blade?
 
Non-magnetic is when steel crosses the Currie point, at 1414F. It is sometimes wrongly called the critical point, which is not the same thing.The critical point is at 1335-1355F ( it varies with the steel type).

52100 austenitizes at 1550F, which is about 150F above non-magnetic. After the steel becomes non-magnetic observe the color, continue heating to a brighter shade of red. Without a lot of experience, or a temperature reading oven or forge, you will just have to guess. It is better to be 50F too low than 50F too high, so go just a little more than non-magnetic in the color. Most people I have watched HT by color have had the steel way too hot. All color observations should be done in the lowest light possible. At night is best, in the shade during the day is acceptable, but will look a lot different than at night.

Blade colors in oven tempering are not a significant sign of the temper. Use a kitchen oven set at 450F and you will be fine. If the blade is clean and oil free, it should be a bronzy-gold color, but it could be a peacock blue or a rainbow of colors if there is any oils or other chemicals on the surface.

The use of watching the temper colors is done when drawing the spine with a torch. It is the straw ( bronze-gold) color you watch move toward the edge. When the straw color is just shy of the edge, dunk the blade in water.

Stacy
 
Being hypereutechtic wouldn't you want to give 52100 an extended soak time to bring all of your carbon into solution?

-Page
 
mmarkh said:
Can you heat treat a knife with a torch using temp sticks. Thank you
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The real issue with HT'ng with a torch and using temp sticks is not allowing the torch or forge flame to touch the temp stick mark on the blade due to the flame being much hotter than the steel. This warning came direct from a TempStik customer service rep.
 
I did a few before I built my forge, one thing to consider is the one brick forge, I would make a box of fire bricks and hold the torch and blade in the box, makes heating a large blade easier takes way less time and heat and allows you to hold at temp a little easier.

The other thing to consider is you can get a nice quench line (hammon?) with this method.

I see canola oil is the quench of choice, why not extra virgin olive oil? Just kidding have fun
 
I haven't been able to find anything conclusive yet, but it would seem that to get all of the carbon into solution and playing with the chromium (chromium carbides) versus pearlite and residual stringers you would want to do an extended soak time (20 plus minutes after uniformly achieving austentizing temp) or you are wasting the benefits of the extra carbon and chromium. Just my thoughts.

Mete any input here?

-Page
 
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