Bobby,

May I ask how you guys heat treated at Haywood? 1070-1080 is similar to 1084 which is quite popular steel and straight forward as far as heat treat goes. Lin

Lin,

I think we treated it, as if it were 1095, and thus set the tempering cycles at too high of a temperature. We normalized, three times, with the first heating to non-magnetic, the second a bit lower, and the third to blood red. Between each cycle we let the blade cool to black. When we heated for the quench, we heated to non-magnetic and then a few seconds more.

During the temper, I think we set the ovens for 450, which is what I believe softened the blades edge?

How do you believe I should heat treat this material? Forge and kitchen oven only options....still saving up for a kiln.

Thanks,

Bob

Bob,

I do all of my 10XX series steels in the same basic way as far as the normalizing goes. The quenchants can be the same, but some of the higher carbon points work well in a faster oil, such as Parks 50.

I suspect the main reason your cutting edges are turning out soft is probably the draw back temp that you are using is a little too high. I always start low on the chart, especially when working with a steel I am unfamiliar with. Then test. If the test shows the edge to be too hard, I raise my draw back temp a little and do it agin. IMO, this should be standard procedure for every new steel, until the maker is very familiar with it. Even though I am faliliar with my chosen steels, I will follow this procedure from time to time, just to keep check on myself.

You said you had this problem in class. Did the whole class experience this? Lin

Yes Lin....however it wasn't until after the class was over that we found out that the heat treat was wrong. I've yet to make a blade with the 1070 that I purchased from Admiral Steel...still working with some of my remaining 1095 and 5160 steels. I believe that the 1070 steel needs to be tempered at around 375 or so?

Thanks,

Bob

Bob,

First of all, let me say this. If you guys were told the wrong draw back temps, it was an honest mistake and discussions like this will help all of us. In fact, I learn my most valuable lessons from mistakes. Like you, this makes me more determined to figure it out and prove it for myself. <img src=' http://www.americanbladesmiths.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' /> I think 375F will be a good place to start as well. If it was the first attempt, I would go back to 360F and test. Remember, testing is a large part of this business. Lin

One other thing. One fringe benefit of taking the class and learning to forge and heat treat is to be quite able to take an entirely unknown steel and determine the general type and develope the proper heat treat for a blade from that steel. I think this should be a goal of all makers who forge.

Thanks Lin for you help, I'll be sure to follow your advice when I try new steels, I think about 50% of what I've learned has come by way of trial and error.

Hi Bobby,

Have you tested any of your steel for hardness after quenching (prior to tempering)? It might not hurt to confirm you are indeed nailing that step prior to testing your tempering temp/soak process. Just a thought. Let us know how it goes.

All the best, Phil

PS -- Here are a couple of links with HT info if you haven't seen them yet.

[list]

Bobby, I know I was one of your instructors at Haywood and while I cannot see myself, nor remember, recommending 450F for 1075, if I mistakenly did I wholeheartedly apologize. 450F would work with precisely hardened 1095 that had a good soak but for the most part 400F is a good range for any carbon steel blade intended for rough applications like the ABS test. 375F on a properly soaked and hardened 1080 blade would leave things above 61-62 HRC, which would be great for a skinner or edge holding fine slicer but not so great for blades that will see much heavier abuse. The qualifier in that sentence is the proper soak, something that is often not readily obtainable without precise controls, thus a blade with lowers levels of austenite solution from a quick heat in the forge could see 58 HRC from a temper as cool as 375F.

From all of this we can gather that there really can be no set temperatures to give exact Rockwell numbers for a temper since the results will heavily depend on your initial heat treatment, that is why it is a good practice to start low and walk your hardness in by bumping up the temp. From what has already been outlined a safe starting point would be 375F, but I would view it as a safe starting point, then 400F then 425F. When things work well you can expect a rapid drop to around 61 HRC and then you will lose around 1 Rockwell point per 20 degrees of temper increase to 58 HRC. At 57HRC or below you will have to start increasing your edge geometry so much to compensate for lack of strength that cutting efficiency and other factors will begin to become awkward for anything other than axes and swords.

Phil, thanks for the great heat treat links, I've just bookmarked them. Kevin, as always thanks for the in-depth response. I've got about 18 feet of the 1070 from Admiral Steel and am looking forward to putting it through the forging and heat treating sequences. I remember you saying that you should stick with a few steels and learn them well. That's why I'm sticking with the 5160 & 10XX series for now....when I get my heat treat oven I might experiment with a few others...after I nail down what works with these steels first.

Thanks Again Guys

Bob