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1075 using just a forge


Robert Carter
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If you were to use aldo's 1075 and just your forge without a Pyro meter to tell what temp you are at, what series of steps would be recommended to achieve a good heat treat with an active hamon? Please Pardon my ignorance if this is an easy question but I am new to the mysteries of heat treating and do not have a lot of expensive equipment. For the sake of argument assume a pukka shaped blade 5.5 inch blade 1.125 inches wide at widest and .1875 inches at thickest point. Specifics are appreciated. Including clay prep.

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What kind of forge do you have?

I use 1075 more than any other steel and I love it.

You should forge your blade and grind/file it to shape and clean of scale.

You need to normalize your steel, in dim light watch the blade in the forge and bring it up to a red orange state checking it with a magnet until it will not stick, get a color chart on your phone or computer this can help too.

You want to be in the 1500 degree range 1500-1550

take it out and let it cool in still air do this 3 times, then clean it up and clay it.

http://greatwaveforge.com/test

This is a very good link on claying blades.

after the clay/cement has dried take it back up to 1550 and quench in warm oil. Veg oil is ok and so is vet grade mineral oil but the best thing would be Parks, or another industrial quench oil.

Hold it in the quench for 10 seconds and then take it out and let it cool, then you can clean the clay and oil off and temper between 350-400 3X for an hour

Grind it again and and start polishing.

Quench in vinger or lemon juice, or ferric Chloride and clean with chrome polish like mothers and etch again and repeat the process. You can find a lot of ways of polishing and etching on the forum here.

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i would forge and grind as usual. leave about 2.5mm - 3mm on the edge, and grind to about 100 grit parallel to the edge.

 

turn your forge right down (presuming you're using propane), bring it up to just non magnetic a couple of times to calibrate your eye - with 1075 the decalescence/recalescence should follow magnetic/non magnetic pretty closely, so use the magnet, but watch for the shadows as well. then bring it up to a shade brighter than non mag, and let it cool to black, then half way between that heat and non mag, back to black, and back up unil it's just non magnetic and cool to room temp.

 

grind off the scale formed from these normalising cycles, degrease the blade (i just make sure i only touch the tang and the very tip on the final grinding pass). mix fire cement with water until it's about the consistency of melted icecream, and apply a very thin wash of clay over the whole blade (you can mix a drop of water on your fingertip into the clay on the blade at this stage to get the thin wash to cover the blade evenly). then add a bead of clay about 1/8th thick where you want the hamon to form, and cover from there back to the spine with a layer of clay about 1/16th thick. finally lay some ashi down from the bead of clay to the edge (little strips of clay about 1/32nd to 1/16th thick - these give the hamon the activity). bake in the oven for about an hour to dry the clay.

 

heat in the forge until the whole blade, including the parts covered by the clay is non magnetic, and quench in hot water from the hot tap or the kettle. quench for a slow three count, and then either into oil, or out for a three count and back into water for another three, and back in til it stops sizzling. temper immediately at 400f for one hour, and grind the surface bark off with a sharp belt - if you hold it up to the light fresh off the grinder at this stage, you should see the hamon as a lighter colour than the soft steel - if you're happy with it, temper 2 more times, and grind down to an edge (dipping in water every time it gets hot) and polish and etch...

 

simples.

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Jake Cleland - Skye Knives

www.knifemaker.co.uk

"We can't solve problems by using the same kind of thinking we used when we created them."

"Everything should be made as simple as possible, but not simpler."

"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe."

 

Albert Einstein

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Thanks guys. I am using a propane forge that u built myself wit h a burner built after the Zoeller forge z-burner. A question to jake, you mentioned heating the water first out of the tap or kettle. Out of curiodity why heat the water? I really appreciate you guys taking the time to answer.

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The hot water makes the quench less severe. When you put steel that is that hot in water it tends to flash boil the water right at the surface of the metal. These bubbles then get out of the way so new water touches the metal, takes a bunch of heat, then moves away to be replaced with the next bit of water. This does not happen as uniformly as one would wish, hence why water will often give more warping and cracking. Imagine all the changing water/metal interface areas, some being liquid water, others being gas, at any given moment. When the water touches the steel it has to take a bit of heat energy from the steel to turn to gas. When you use pre-heated water it doesn't take as much energy from the steel to get from liquid to gas. This makes the quench a little more even, and quite a bit slower/ less harsh. If we assume 65 F water to be the ideal cool water quench temperature, cooling it to 33 F only makes it about 5% more effective (harsher). However, if we heat the water to 100 it is about 35% as effective (65% less than 65 F water). This is due to the quicker heat exchange and shorter times for the water touching the metal to go from liquid to gas.

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thanks for these last two comments. I do things almost exactly as Jake has described, and I learned without knowing why that taking hot water and letting it sit for the half hour or so required for my steel to come to temp and soak in my kiln works best.

 

Did not know why it did, though.

 

I use low manganese 1075 for a LOT. It is just about perfect for hamons with a forge. great stuff.

kc

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please visit my website http://www.professorsforge.com/

 

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I used W-1 extensively for the japanese style stuff I did for the same reason, worked with water quench very well with minimum issues. I found the most important thing, heat treating out of forges, was to come up slow and careful, and not overheat.

Water has no mercy if you overheat the blades.

Edited by R.H.Graham

Randal

www.rhgraham.simpl.com

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I followed Jakes advice and it worked exactly as he said. I did however see afterwards that 3 micro fractures had started near the tip. I did the 3 second interrupted quench in water then into canola oil wit h both warmed to about 120 degrees farenheit. Would this be due to heating the blade too fast? Also the blade was dead straight before quench but curved upwards during. Is lthis due to the water, or the blade geometry?

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Curvature in a water quench is normal.

 

Those cracks are typical of the blade either being to thin on the edge for a water quench, or being overheated before the quench.

 

Also, interrupting the quench is good, and can help, although I personally think the quench in oil after the first quench is pointless.

If it survived the first phase of hardening in the water, it will survive being finished off in water as well.

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Randal

www.rhgraham.simpl.com

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