non magenetic 1084

I was curious about quenching 1084 when it becomes non magnetic?
I'm aware that this is a little short of the ct for optimal hardness.
I may be a little ignorant on these matters but if all the carbon does not get into solution as iron carbide, is this not the same as drawing carbon out of solution during the tempering phase? Maybe the peice could be just left hardened at not magnetic without tempering???
Have I got this right?
Please enlighten me, I will be ready to heat treat first razor soon without a thermometer, any advice welcome.

Deckard

Deckard,

Unfortunately, not fully hardening 1084 does not yield the same result as tempering fully hardened 1084.

When you heat 1084 (a Eutectoid Steel) up to 1500 degrees F and hold it there for a few minutes, all of the iron and carbon will form Austenite. When you quench it rapidly enough to avoid making Pearlite, you will get Martensite. The Martensite is very hard, but somewhat brittle, so you need to temper it to relieve internal stresses that might cause it to crack. You end up with tempered Martensite.

If you only heat your 1084 to Currie point of 1414 degrees F (non magnetic), you will have a mixture of Austenite, Ferrite, and Cementite. When you quench that, you will get Martensite and Pearlite, which is not as strong as all Martensite.

If you quench your steel but don’t temper it, it is going to be brittle and may crack on its own from the internal stresses.

A while back Dr. John Verhoeven graciously posted a free paper called The Metallurgy of Steel for Bladesmiths and Others who Heat Treat and Forge Steel. He has since taken down the link on his website and published the paper as a book. I have both the book and the paper, and they are essentially the same. Someone in Germany still has the .pdf of that paper posted, so you can download it for free. Here is the link. It's very worthwhile reading.

Also, Kevin Cashen has all kinds of great info posted on BladeForums. Take a look at the stickies at the top of the Shop Talk sub-forum. The one entitled “Perhaps a basic curve discussion?” will probably answer most of your questions. The process and principles of quenching is another good one.

I’ll post the pages for Heat Treating 1080 and 1084 below. The TTT diagram for 1080 is essentially that same as what the 1084 diagram would look like, but the authors didn’t include one.

http://i44.photobucket.com/albums/f2...0-HTG-p-77.jpg

http://i44.photobucket.com/albums/f2...77-cropped.jpg

http://i44.photobucket.com/albums/f2...78-cropped.jpg

Kevin Cashen also wrote up some instructions for heat treating 1084, which someone has kindly posted. (When you read it, you’ll notice a bunch of odd question marks. They appear to be caused by some program being unable to cope with the degree symbol.http://i44.photobucket.com/albums/f2...s/rolleyes.gif)

Christopher,

Thank you for what is a very comprehensive answer.
I love the data sheets- these are the sorts of details I like. The graphs kind of look familiar from my college days.
I am making a first attempt at this with very basic equipment and using Bob Altmans albums as my guide through the process.
I guess I may have to watch for decalescence at the same time avoiding the risk of excessive grain growth (not sure if this is a real risk with 1084).
Because of section size I'm not sure if heated peanut oil is a suitable quenchant? Getting parks 50 in UK is difficult, maybe brine would be ok?

Any practical advise to optimise a critical part of razor making process is always welcome.

Thank you for information

Deckard

Deckard,

Brine will work, but you risk cracking your blades.

As far as grain growth, as long as you don't overheat your blade it won't be an issue. Someone on bladeforums proved it by soaking some O-1 for hours without grain growth. Of course, decarb would be an issue.

Houghton International is apparently the largest manufacturer of Heat Treating oils. They make a fast quenching oil (7-9 seconds), which I believe is called Houghto-Quench K. They also have distributors in the UK and a reputed to be very friendly to small time heat treaters (unlike the SOBs at Park Metallurgical). They also publish a free pamphlet on Quenching.

Be sure to download the Verhoeven book. It's chock full of information you need. As of today that link is still valid.

Since you are interested in heat treating, you might also want to visit HypeFreeBlades, and the forums there.

Hi Chris,
I'm so gratefull for your help, thanks again for answers to my thoughts.
Already downloaded book and had a good look, a bit theoretical in places but am able to apply in practice due to engineering background.
What's your opinion of temperature crayons from omega.com, it's got to be better than nothing, untill I've calibrated my eye. I'm talking very low tech, at first anyway. Maybe I will upgrade equipment if I'm encouraged by results.
Am a bit behind schedule at moment due to family priorities as I can only manage couple of hours a week at best, still got to thin the blade and remove stress raisers.
Will join other forums and have a look at the links you provide.
I'm always impressed by the wealth of knowledge on this site.

Best Regards
Deckard

Deckard,

I have never used the temp crayons but, as you say, it's probably better than nothing. However, with a little practice, it may be possible for you to judge the temperature by eye. Watch for the decalescent point and exceed it just slightly (the point where all of the shadows have just gone out of the blade).

What are you going to be using for a heat source. If you are using a gas forge, you can usually pick up a temp controller on eBay for a reasonable price. I use a propane forge with a blower. I have mine set up with an Omega controller and thermocouple (which sticks in from the back of the forge). I never got around to setting it up with a solenoid valve, so I control the gas and air flow by hand and just use the controller as a temp gauge. Still, it works well.

http://i44.photobucket.com/albums/f2...orgeforweb.jpg

As for thinning the blade, you might want to be careful about that. I recently showed Tim Zowada a couple of razors that I'm working on. I hadn't hardened them yet. He told me that I had already had probably ground them too thin and that they would most likely warp. He suggested just profiling the razors, hardening them, and then doing just about all of the grinding on the hardened blade. Of course, with that method you need to be very careful not to overheat the hardened blade. I recently set my grinder up with a VFD, so I can slow my grinder down to a crawl and avoid overheating. I don't know whether or not that would be an option for you...

http://i44.photobucket.com/albums/f2...th-VFD-01a.jpg

Deckard,

Just a correction to my previous post; TZ actually grinds the edge down to about 0.030" - 0.040" before heat treating. I swear, my mind is like a steel sieve some days... :gaah:


Here are the two razors I'm working on. I haven't gotten around to heat treating them yet.

http://i44.photobucket.com/albums/f2...t-treat-01.jpg

Christopher,

Those razors look great, like the french point.
I'm planning to thin to about 0.060".
The actual blade will work out to about a 7/8 grind, so I figure if I get warping that final grind can't salvage I can regrind it to a 6/8 or maybe 5/8 if required. I'd have to thin the spine to achieve the correct bevel angle if I had to do this, I do have access to a surface grinder where I work.
Not sure if my private message was recieved by you, I'll have to set it up to save my messages.

Deckard