Thank you, Jeremy and Brion, That's what I did is do a normalization for the 3 cycles and put into vermiculite and will H/T tomorrow. Jerry

Brion, I didn't get your post before I went through all 3 cycles, so I hope this combo will work. I'll let you know with my tests. Jerry

It takes my Even Heat 1 full hour to cool off from 1500 to 400 with the door partially open.

Then I close the door and wait for it to "find" itself and either cool off more or slightly bump it up by turning it on.

I use Texaco A for hardening 5160.

I temper my 5160 at 350.

Wait until your oven is stabilized at your target temp, whether it be austenizing or tempering, for at least a full 1/2 hour before placing your knife in. There's nothing to lose if you wait, but a lot to risk if you don't.

Thank you, Karl, I've noticed that the temp takes a little while to settle. I also noticed when I bring temp up say to 1500 and hold for 10 min. if I open the door and put a knife in for normalizing the temp will drop 50 degrees, so I'm thinking I leave the knife in until my temp comes up to the 1500 again and soak for a couple minutes. Your thoughts. Jerry

A two minute soak may work but I usually leave it for 5 minutes to be sure that everything has equalized. With my Evenheat it helps to stop the program & restart it after putting the blade inside. That way the oven will realize the drop in temperature right away.

Gary

My thoughts are that the oven needs to equalize at any target temp for more than 10 minutes.

When I'm working with a cold oven and I'm going to temper, I let it sit at say 400 degrees for a full hour before I put the blade in.

When I austenize, I let it sit at 1500 for a good 20-30 minutes.

I want the oven's mass at that temp, too, not just the inside atmosphere.

When the oven cycles, like in your example where it dropped 50 degrees, the temp coming off those coils is FAR greater than your target of 1500.

If your oven's mass is fully up to your target temp, the rebound is less and quicker.

Don't get in a hurry.

I watched my electric bill one time when I was doing a LOT of heat treating.

And compared to another month when I did none at all.

There was no difference.

Take your time.

There's no hurry.

Let your oven soak at target temp a long time.

It's better than rushing things.

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Thank you, Karl, I've noticed that the temp takes a little while to settle. I also noticed when I bring temp up say to 1500 and hold for 10 min. if I open the door and put a knife in for normalizing the temp will drop 50 degrees, so I'm thinking I leave the knife in until my temp comes up to the 1500 again and soak for a couple minutes. Your thoughts. Jerry

Thank you Karl, I didn't realize the oven mass not holding the temp. New to H/T oven, this will help greatly. Jerry

The 5160 did not harden, I think it lost carbon. I am going to cut and grind test pieces, go through complete thermal cycles and see where my mistake may have been. Thank you for everyone's help, Jerry

Jerry,

I want to underscore a point made early in that you initially indicated that you tempered the 5160 blade at 400 F. That is just too hot for 5160. The recommendation of 350 F is more correct. Also, I would point out that the ASTM indicates that you should be able to get 64 on an RC for a steel with .60 carbon. While that is possible in a controlled laboratory it is frequently not achieved in most shops. Expect a 62 to 63 RC. If you get a 64 reading great but there are a lot of variables to control.

Tempering is a function of both time and temperature but even a brief period at too high a temperature can have effects especially on the thinner material of the edge. I tend to creep up on the tempering temperature in that the first tempering bath with 5160 would be 325 and then for the second tempering cycle I would take it up a to 350 after testing the edge. If I am not happy I will take it up another 10 degrees for a 3rd cycle. My experience is that 10 to 20 degrees can make a difference. Now, it all depends on the size and use of the blade as to where you want to end up. I temper for a slightly harder blade on small utility knives versus big choppers. I am also more likely to marquench on the bigger knives.

Dan Petersen

Thank you Dan,

I am going to do some test pieces and make sure I have good control to see where I went wrong. jerry

I watch amount of time it is taking for our EvenHeat to cycle on and off. Early on, when either climbing to temp or when temp is initially reached, the "on" time is notably longer than the "off" time. As the oven equalizes, the "on" to "off" time does also. It's easy to see when a person knows the temp is equalized (the oven has been at a set temp a long time) by watching and counting the number of read out flashes with elements on or off. I should do a study on it but I always forget to.

Brownell's Tough Quench is the same as Houghto-quench "G" and so is McMaster-Carr's "11 second" quench oil. Houghto-quench "G" is nearly identical to Park AAA. Park AAA is not as use-stable as "G" and is said to be very slightly faster when new and very slightly slower when well used (not enough speed change to amount to anything, really).

Houghton International's chief metallurgist (Scott McKenzie) says Houghto-quench "G" will fully harden 1/4" 10XX, W1/W2.

"G" will not work with standard methods for producing hamon (clay, etc.) I have found it will produce "natural hamon" (not fully quenching thick sections) on W2 with spines left thicker than finished thickness, if a person interrupts the quench. Interrupted quenches can be problematic in at least minor ways. The hamons are very pretty, though.

I use Houghto-quench "G" for W1 (1.20C), W2 (1.03C, O1 (.92 and .95C), L6 (.72 C), various 10xx and O1 damascus, and would use it for 5160 and 52100 if I used those steels. I have Houghto-quench "K" (functional equivalent of Park 50 and more long-term stable) and did use it for 10xx and W1/W2 but don't bother any more.

A person can buy McMaster-Carr "11 second" oil in 1gal or 5gal quantity. Lots of folks (Kevin Cashen, for one) advise using a lot of oil (gallons), and there are reasons for that. Industry measures amount of steel that can go into a quench with full expectation of through-quenching with a 1gal. per pound of steel ratio. I suppose there are instances (specific steels and/or needed outcomes) that are different, but it is the general rule of thumb.

Mike

PS... I do go on... nearly forgot one of the parts of the thread. It took a while for me to understand tempering (thanks to a lot of people who wouldn't give up on me). A tempering table shows hardness change at different temperatures with a swoopy curve. Most tables show austenitizing temp prior to quench, and some show the test steel's specific chemistry. The swoopy curve showing hardness at a given tempering temperature is always related to a starting hardness. If a blade's as-quenched hardness is less or more than a chart, the swoopy curve will only show you relative hardness change (give or take a little). It's not like 400F is going to temper out to 59-RHc from both an as-quenched hardnesses of 66 and 62 (same steel).

Different austenitizing temps get a person different swoopy curves, too, and so do chemistry differences (same steel) at equal austenitizing temps.

There are a lot of little variables in all of this... Dan said he sneaks up on tempering hardness. Kevin does that too. So do others.