Adventures in heat treating

[KYCaster]

Possum asked a question about quenching in the cast boolits section which led to a discussion of the TECHINCAL aspects of heat treating. Rather than hijack his thread I'll post this here in Off Topic.

When I worked in the factory making permanent magnets, a big part of my job involved heat treating. Mainly concerning QC and process development.

One day, the head of our department (PHD in metalurgical engineering) came out in the shop with a five gal. bucket of quenching oil that was the solution to one of our chronic problems, quench from 2100deg. F to room temp. as fast as possible without fracturing the material. Part of the problem was the vapor barrier around the material retarding the heat transfer and this oil with its higher flash point (850* vs. 650*) was the answer to every problem since the invention of bronze alllys.

"OK", sez I, "I'll get a five pound sample and try it". "No", sez he, "I want to duplicate the production process, so use one of the 80 lb. production lots".

"Well", I asked, "If you want to duplicate the production process, wouldn't a 55gal. drum of oil work a little better?" "This is what we've got. Just do it." was his reply. So I asked, "Since this is your project, I assume you want to be here to see the results?"......."Of course."

So, time for the test, he shows up with two other engineers and the rep. from the oil company. I poured four gal. of the oil into a metal bucket, he sez, "aren't you going to use all of it?" (Archamedes was rolling over in his grave) So I filled it to the top.

I made them wait while I donned my costume, towel to cover the back of my neck, insulated welder's cap, welder's leather jacket, leather apron, welder's gloves and full face shield. They seemed to be amused at my caution.

Finally ready, I took the tray from the furnace and gingerly placed it in the bucket, then beat a hasty retreat. As I passed my assembled audience, I heard the WOOF and felt the heat on my back. I thought I would be trampled in the stampeed!

Jerry

[keeper89]

Another fine example of what happens when people are educated beyond their intelligence level.......thanks for sharing!:-D

[felix]

Jerry, steal some of that oil and do a boolit test. I really wonder if the difference in hardness gained is worth the hassle. ... felix

[waksupi]

I was once told, the old way of cooling an anvil, when they were being made, was to take the hot forging, and place it immediately under a large, vertically dropping, stream of cyanide. This would take the face to the proper hardness, while leaving the base somewhat softer. I don't know if it is true for sure. That would be a lot of flowing cyanide. Nothing I would want to be too close to!

[David R]

Street smarts VS Book Smart.

[redneckdan]

I deal with this a lot at Michigan Tech. Just tonight, I was talking with a student who rides mountain bike like I do. He made a change to his front tire and can't figure out why his shock rear shock tuning went all to hell, says he gets massive bob at certain speeds. I know for a fact that he learned about resonance frequencies but I guess he hasn't made the jump from book knowledge to application.[smilie=b:

[grumpy one]

I was once told, the old way of cooling an anvil, when they were being made, was to take the hot forging, and place it immediately under a large, vertically dropping, stream of cyanide. This would take the face to the proper hardness, while leaving the base somewhat softer. I don't know if it is true for sure. That would be a lot of flowing cyanide. Nothing I would want to be too close to!

Sounds as if the objective was to carburise the face of the anvil more than to cool it. Not many decades ago most welders had a can of a mixture of sodium and potassium cyanide for small carburising jobs - just cover the surface with the powder, and heat it with the oxy torch so that the molten cyanide covered the surface for a while. It wasn't a process that would meet today's industrial health standards, but it wasn't as dangerous as it sounds either. At its fuming temperature cyanide oxidises extremely quickly. Incidentally I'm guessing that the "flowing" cyanide you're talking about would be powder, not molten cyanide. Also, the stuff is 95% sodium cyanide and only 5% potassium cyanide. It's no health food, but not as suicidal as it sounds. Nevertheless the safety inspector at the place where I used to work got pretty exercised once when he found the guys were putting their lunch pies over the small gap between the edge of the heat treatment cyanide pot and the housing around it, so the gas fire underneath would heat them up. Not sure all those pies were wrapped, either.

Geoff

[Gibbs 505]

KYCaster that was wonderful!!

[Four Fingers of Death]

That's what my grandpappy used to call it 'book smart.' he sorta said it slow like and the way he said it, he didn't have to explain anything, you knew exactly what he meant. :-) Mick.

[shooter575]

You could also use the cyanide by heating the steel to a bright red heat and diping it into the powder.This worked faster than the carbon powders used today.ie Kassen it.
Couple years ago I was cleaning out the old barn and had a bunch of junk to get rid of.Had a full gallon jug of DDT and some empty unmarked chemical cans.I took them to a county run site to dispose of.The EPA fella got real excited when he saw one can that was 8" square x20" tall with a funny looking big screw on lid.
It was a cyanide can.Only one I have ever seen.

[grumpy one]

The cyanide we used here for small jobs was in a yellow can (paper label wrapped around a tin-plate can) about the size and shape you describe, including the screw-top, branded "Hardite". I think most welders had one of those cans under their steel bench even in the mid-1960s. I've stood there while they used it, and none of us got excited about it, though I did ask my father if it was a problem, and he said it wasn't because it was only 5% potassum cyanide and the 95% sodium cyanide wasn't that big a deal if you were careful around it. The stuff used for industrial heat treatment - the traditional cast iron pot holding one or two hundred pounds of molten cyanide - had 15% or more of potassium cyanide, but even in the 1950s there was always a fume hood over the top of those pots. Where I worked they used to regularly do lab tests on the deposits inside the fume hoods. The chemist told me that in decades of doing those tests, he'd never detected any cyanide - it was always completely oxidised.

Having said that, if you ever find an old can of Hardite, for Pete's sake don't start using it, or even keep it around. Kids are just too hard to replace.

Geoff