Heat treating Aldo's 1075

[Storm W]

I'm getting ready to make a large Bowie with some 1075. Its been a long time since I have used it but last time I had problems with it not fully hardening in canola and had to use water. Now I'm wondering if that was because I needed to normalize it. I have a oven to HT with now and am hoping to do a hamon. I was pretty new the last time I used it and the knives sucked but the hamon was better than it had any right to be. If anyone has any advice about what works for them I would love to hear.

Thanks

 

[Stacy E. Apelt - Bladesmith]

It probably isn't necessary to do a big normalizing procedure on 1075 unless it has been heavily forged. It is hypo-eutectoid and there is no surplus carbon to deal with. A few descending heat and cool cycles will be fine if you want to. Do these at 1650, 1550, and 1450, with a quench after the last one.

First suggestion is to use Parks #50 … or brine.

As for the hamon, use an austenitization temp a bit lower, around 1485F is a good place to try. 1075 is a shallow hardening steel and lends itself to a very nice hamon.

 

[Storm W]

It probably isn't necessary to do a big normalizing procedure on 1075 unless it has been heavily forged. It is hypo-eutectoid and there is no surplus carbon to deal with. A few descending heat and cool cycles will be fine if you want to. Do these at 1650, 1550, and 1450, with a quench after the last one.

First suggestion is to use Parks #50 … or brine.

As for the hamon, use an austenitization temp a bit lower, around 1485F is a good place to try. 1075 is a shallow hardening steel and lends itself to a very nice hamon.

Thank you very much sir.
I still gotta get some parks to 50. Since most of what i'm working on is stainless and tool steel I haven't worried about it. I will brine it up. I will give that temp a try.

 

[Stacy E. Apelt - Bladesmith]

By lowering the austenitization temp you have a shorter drop for the edge to remain supercooled austenite while the spine goes into pearlite. As it hits 400F, the austenite converts into martensite. The junction of the two structures is the hamon. Sometimes you have to play with the temp a bit to find the sweet spot. Since 1075 is normally austenitized at 1500-1550F, dropping tp about 1485 should be good.

 

[Storm W]

By lowering the austenitization temp you have a shorter drop for the edge to remain supercooled austenite while the spine goes into pearlite. As it hits 400F, the austenite converts into martensite. The junction of the two structures is the hamon. Sometimes you have to play with the temp a bit to find the sweet spot. Since 1075 is normally austenitized at 1500-1550F, dropping tp about 1485 should be good.

Very cool. That was a point I didn't get before. That really helps. Thanks

 

[Willie71]

I’ve used 1475f for more activity. I did one at 1450f, and the activity was great, but the hamon went to the edge at the heel on a big Bowie.

My 1075 hardened fine without normalizing and cycling. Not sure if all of Aldo’s 1075 responded the same.