HR 1075/1080 Questions?

D

Dixieblade57

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Jun 20, 2007
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I just purchased some steel for my next venture into the knife making world, forging my own blades, instead of reduction method. What I have on its way is HR 1075/1080. Below is a link to Admiral Steels Heat treating information?

http://www.admiralsteel.com/reference/heattrt.html


It seems that is gets harder when drawn at its minimum temperature of 400*. According to the chart the hotter it is drawn at the less the Rc factor!

OK, here is the question, am I reading the chart correctly the optimum drawing temperature world be 400* F to obtain a Rockwell hardness of Rc59?

Another thing that I found interesting is that annealing temperature and the hardening temperature are very close!

Any of you that use HR 1075/1080 I would appreciate any info you might be able to share with on this steel, as this is my first time using it! All my previous blades were done by reduction using the steel of an old two man saw!
 
Yep, you're reading it right.

The hotter you temper it, the softer it gets. (That's not just for 1075, by the way- goes for all steels that I know of.)

That's why when you're regrinding something that's already been heat-treated (like an old saw blade), you're careful not to let it overheat and change colors. You get it too hot and it gets too soft.

:thumbup:
Mike
 
I use a lot of the Admiral 1075/1080. It's about the simplest steel you can work with. It forges easily, and annealed it grinds and drills easily. I've always been happy with the edge holding on both big and small knives, even just using a forge for heat-treating and doing it by eye (and magnet). I usually temper at just under or right at 400 for smaller knives, 425-450 for larger knives.
 
MSCantrell said:
Yep, you're reading it right.

The hotter you temper it, the softer it gets. (That's not just for 1075, by the way- goes for all steels that I know of.)

That's why when you're regrinding something that's already been heat-treated (like an old saw blade), you're careful not to let it overheat and change colors. You get it too hot and it gets too soft.

:thumbup:
Mike
Click to expand...

Thanks for the info guys. It makes perfect sence when you explain it that way. Sometime its hard to see the forest for the trees, sort of thing!!!!!!
 
I've wanted to try some 1075/1080 for a while, but havent gotten around to it. There are several makers that use it here with good results. For small knives intended only for cutting, like skinning knives or vegetable knives, you could try tempering it lower than 400 F for a hardness above 60. No guarantees, but the higher hardness should allow it to hold an edge longer, providing the dulling isnt from chipping, a possibility at the higher hardnesses.

For what its worth, knife steels behave about the opposite from other metals. Heat 300 series stainless to critical temperature and quench it and you have just annealed it. Heat one of the heat treatable grades of aluminum and quench it and then reheat it at a lower temperature and it gets harder, not softer. There are a few steels that will harden during tempering, but they are expensive and I wouldnt wish forging them on anyone with a hand hammer.
 
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