Quench Speed Information Needed

[Mike Krall]

You guys aren't done yet - are you?

 

Which fork you wanna take, Karl?

 

Mike

[Mike Blue]

I finished reading the Houghton pdf. Not a bad summation of what could have been a lot of complicated metal quenching. I can't argue with the conclusions about the changing chemistry or contamination of the oils used in quenching. The factors mentioned are, from an industrial point of view, like effects that they would have noticed, given the volume of the work they are doing and the precision that the engineers have specified for the whole job. In my mind, for say a knife production shop, thousands of blades would all have to be identical at the end of the production line. With that kind of volume, I can't argue with their recommendations.

 

That being said, I'm a little put off that they leave this suggestion without any clear idea of how much of an effect the contaminants and chemistry changes will make. They leave it at saying there's an effect but do not give much of a degree of expected effect, nor do they suggest any length of time over which to expect such changes nor their magnitude. How fast does oil degrade? How much hardness change are they worried about over time? How many blades put through a typical oil bath before noticeable change in hardness values are seen? Things like that would be helpful.

 

Plus after all that discussion of the problems with oil, I get the distinct feeling that the desired outcome of the paper was to sell polymer quenchants.

 

Personally, I haven't noticed any difference in practice over the years. I did learn something. Glad I'm not dead yet.

[kb0fhp]

Hello Scott,

 

How would canola oil hold up as a quench oil?

 

Mike

 

 

It does well. There are several commercial heat treaters using a canola type - specifically our product Bio-Quench 600. It is a refined canola/vegetable oil. Excellent quenchant. It does tend to absorb water, and has a tendancy to cause staining (the type of burned on stained like frying something), but it is an excellent quenchant - very unstable vapor phase, high boiling temperature, high flash. Fast where it needs to be - and slow where it needs to be - I really like canola based quenchants.

[kb0fhp]

I finished reading the Houghton pdf. Not a bad summation of what could have been a lot of complicated metal quenching. I can't argue with the conclusions about the changing chemistry or contamination of the oils used in quenching. The factors mentioned are, from an industrial point of view, like effects that they would have noticed, given the volume of the work they are doing and the precision that the engineers have specified for the whole job. In my mind, for say a knife production shop, thousands of blades would all have to be identical at the end of the production line. With that kind of volume, I can't argue with their recommendations.

 

That being said, I'm a little put off that they leave this suggestion without any clear idea of how much of an effect the contaminants and chemistry changes will make. They leave it at saying there's an effect but do not give much of a degree of expected effect, nor do they suggest any length of time over which to expect such changes nor their magnitude. How fast does oil degrade? How much hardness change are they worried about over time? How many blades put through a typical oil bath before noticeable change in hardness values are seen? Things like that would be helpful.

 

Plus after all that discussion of the problems with oil, I get the distinct feeling that the desired outcome of the paper was to sell polymer quenchants.

 

Personally, I haven't noticed any difference in practice over the years. I did learn something. Glad I'm not dead yet.

 

Mike - standard metallurgist answer - "It Depends". BTW, in the interest of clarity, I work for Houghton. I am their technical person for quenchants. Regarding contaminants, a lot depends on the type of contamination. Different contaminants have different effects. For instance, organic acids tend to cause staining, and will slow down a cold oil, but speed up a martempering oil. A lot depends on how the oil is used and abused. If you don't exceed one pound of parts to one gallon of quenchant, you will get long life (months/years). A lot also depends on how much work you run through it - if you run a load of parts that exceeds the one pound - one gallon rule, life will be shortened because the oil will actually overheat and the antioxidants will be expended. Coolants from machining, can also cause staining, as well as the residue after heat treatment can cause non uniform effects. To give you an idea, most oils will last a LONG time in an industrial setting, as long as the oil is replenished from drag-out. Most oils are thrown away because of staining, before they start causing problems with metallurgical properties. That way you always add new additives (speed improvers and anti-oxidants). For the hobbyist, as long as you don't over heat the oil (one pound of parts to one gallon of quenchant), you will get very, very long life. Since the amount of oil is very large compared to the amount of parts in a typical hobbyist setting, and the oil temperature does not rise very much (probably less than 25-50 degrees or so) - you will get very long life - it will probably last you a lifetime, as long as you use a quality oil from the beginning. If you email me at smackenzie@houghtonintl.com, I can email you some papers on contamination and the specific effects.

 

That paper or booklet, is/was designed to be really non-commercial in nature. If you notice, not one time was a specific product mentioned. Regarding polymer quenchants, we describe a multitude of different quenchants - even those by our competitor. It was designed to be informational and not a tout on specific Houghton products. If you have any specific recommendations, I would be glad to hear them. I am looking at revising the document when I have time as it has not been revised in many years. But remeber, it is targeted at commercial or OEM heat treaters, and not the hobbyist.

 

I hope that helps - and don't be shy to ask me a question or post a comment.

 

Scott, aka KB0FHP

Edited June 15, 2008 by kb0fhp

[kb0fhp]

On the industrial/scientific side of the equation where they get paid to pay attention to details, there is a published effect. Can't argue much with that. I guess the question I have leftover is "does it really make a difference?" How long is the interval before an oil fails?

 

A part of me respects all the science that has refined this craft to a huge degree. I can't argue against being precise and controlling variables, I do it myself.

 

But realistically, practically, economically, does it matter that someone can hit a Rockwell C scale point of 60.35 every time? How will the customer be able to tell the difference in the field? It's one thing for me to do it, if I require that sort of precision from my efforts. It's quite another when this sort of thought process begins to dominate the whole craft and a bias develops against smiths/makers who don't adhere to the strict requirements of whatever the oil du jour is. We've been over this with the wide variety of wonderstahls and liquid nitrogen and you name it.

 

Whatever happened to making a knife that was "good enough," with simple tools that helped the juniors in this craft get off to a good start without feeling that there was no hope of ever catching up to the more experienced because they don't have exactly all the right tools?

 

I think that all this discussion is very helpful when it comes to troubleshooting all the little demons that interfere with our routines. I don't know if the detail work should drive the whole business.

 

Mike - it depends on the application. For instance, when I ran a heat treat shop for Boeing, we made landing gears. They had very stringent property and distortion requirements. In other applications, such as automotive, the requirements are just as tight. For instance, for heat treating cam shafts, they have very demanding requirements for the depth of case and the hardness profile at the surface and at the core, as well as a specific depth in the case. For instance, having a soft camshaft can wear down the lobes and have a very detrimental effect on the engine - Pinto engines failed because of a faulty heat treatment on the camshaft. Gears for transmissions also have very stringent requirements for distortion and properties. In one application, if a gear fails in a wind turbine - and those gears are 96 inches in diameter and 3 feet thick - it costs $250,000 to pull the gear from the transmission on top of the tower. This does not include the price of a new gear.

 

The journey man tests for knife making are very severe. It requires an attention to all aspects of the fabrication, one of the main parts is heat treatment and quenching. If it wasn't done properly, it will fail the tests. But for many applications, heating it to cherry red and throwing it in a bucket of oil will work just fine. It just depends on what you are trying to do. By controlling all factors, it helps repeatability so that the knife or camshaft or landing gear, is the same as the one you made one week ago, and the same that you will make 10 years from now.

 

Also, remember, something that you make for a customer or yourself, often has your name on it. It should reflect the producer. It the requirements are not stringent, then the process may not be stringent. But remember, most of the industrial stuff is made to perform in a given environment. The manufacturers want the customer to be happy, and not have a product that is variable in quality. It is also cheaper to make if they are all produced the same.

[kb0fhp]

I'm not personally aware that oil has a lifetime, but can imagine all the variety of stuff that would get into the oil bucket over time. Those could affect the process, but I've not noticed any significant problem to this point. Stuff still gets hard. This is the barrel into which all things get thermal cycled, so I expect a good deal of scale in the bottom someday, but that's about it. Now the quench-oil companies would be very happy to have us all believe there was a lifetime to their oils. That way we'd buy more. Hmm, seems like the car companies do that to us already.

 

Oils do have a lifetime, it depends on how it is used. For light use, like quenching an occasional blade, and not letting the oil get too hot - a good rule of thumb is one pound of parts to one gallon of oil, if it is a quality oil, it should last a long time, even years or decades. If you exceed this rule of thumb, the temperature of oil will go up, and the oil will start to break down. It will become oxidized. If there is a robust antioxidant package in the oil, it will be able to compensate for this oxidation - but only to a point. Eventually the additive package will become depleted, and the oil's properties will change. For instance, viscosity will increase, and staining will become apparent. The quench speed will also change - martempering oils will get faster (up to a point, then they will get slower because of the viscosity has greatly increased) because the vapor phase will become less stable, and cold oils (those used below about 180F) will become slower because of viscosity effects. Then you run the risk of missing properties.

 

For instance, I have a commercial shop that is making gears for automatic transmissions. They quench 5000 pounds in a 4000 gallon quench tank, and the oil is a quality martempering oil, and the temperature of the oil is maintained at 275F. They have a life of about 6 months before the oil starts staining and causing low properties. The oil has become severely oxidized.

 

If it gets contaminated with water, greater than about 500 ppm of water, then the shape of the cooling curve can change and you can get upper transformation products, or soft spots. You can also get cracking.

 

But again for the light use of occasional quenching small loads compared to the volume of oil - it could last a lifetime.

[Mike Krall]

That is a lot of education for a Saturday night... thanks, Scott.

 

Mike

[cdent]

Thanks to all for the discussion, and thanks Dr. M for the explanations.

 

Happy fathers day, Craig

[Mike Blue]

Thanks Scott, I have no issues with your discussion. The "scale of economy" certainly applies in the large expensive parts industry and I would suggest that most makers have not a little heartbreak when one of their hard won blades goes south in the heat treatment cycle. More information is always good. I was reacting to a concept that I'd not yet considered and hadn't contemplated. Now I have another variable to keep track of.

 

My first reading of the Houghton pdf may have implied too harsh an opinion about what was being sold. I interpreted a bias toward the advantages of polymer quenchants. I don't have any problem being wrong about something that I now understand to not be there.

[kb0fhp]

That is OK Mike - no problems

 

As long as you keep to the "one pound of parts to one gallon of quenchant" rule of thumb, you will get long life and quality work. Just keep the water out of it, and filter it occasionally and you will be rewarded with repeatable results. It is like anything else - if you take care of something, and do occasional maintenance, things will last a long time.

[Brian S. Pierce]

Scott, is there any way you could rank the relative quench speed of vegetable oils like olive, canola, and peanut compared to the others on this chart? How about mineral oil, ATF or DOT3 hydraulic brake fluid?

 

 

Thanks,

Brian

[Matt Bower]

Mike (Krall):

 

Sorry I missed your question; somehow I missed a lot of the end of this conversation. The other day I discovered that Don has Houghton on Quenching right here on his site: http://dfoggknives.com/PDF/Houghton_On_Quenching.pdf

 

 

Mike Blue,

 

It may well be that for the average small maker who doesn't abuse his oil, its life is effectively infinite. (I haven't used mine enough to have a personal opinion.) But even if that's true, always there's bound to be one guy out there who's edge quenching a couple dozen blades a month, flashing his oil constantly, and can't figure out why he's having trouble getting them to fully harden. That guy could benefit from knowing that burning your oil will hurt its quenchant properties. Accurate information is almost always good to know, if only so you can determine that it doesn't apply to you.

[Mike Krall]

Mike (Krall):

 

Sorry I missed your question; somehow I missed a lot of the end of this conversation. The other day I discovered that Don has Houghton on Quenching right here on his site: http://dfoggknives.com/PDF/Houghton_On_Quenching.pdf

 

You didn't miss it, you just didn't see it as soon as it was there... thanks, Matt.

[kb0fhp]

Scott, is there any way you could rank the relative quench speed of vegetable oils like olive, canola, and peanut compared to the others on this chart? How about mineral oil, ATF or DOT3 hydraulic brake fluid?

 

 

Thanks,

Brian

 

Brian:

 

It would be hard to classify the ATF or brake fluid. If it is assumed that it is a straight mineral oil (and that would be the worst case), then I would expect it to be a slow oil (17-20 GMQS), and similar to machine oil. I would put the vegetable oils close to cottonseed oil. But that is an estimate only. Personally, I really don't like the use of ATF or brake fluid. It contains some additives, such as zinc that is good for lubricity, but is not appropriate for quenching. The use of an oil suited for quenching is best, and will provide the best results. To some extent, this would include the vegetable oils, as long as the water is driven off from the oil.

[Brian S. Pierce]

Brian:

 

It would be hard to classify the ATF or brake fluid. If it is assumed that it is a straight mineral oil (and that would be the worst case), then I would expect it to be a slow oil (17-20 GMQS), and similar to machine oil. I would put the vegetable oils close to cottonseed oil. But that is an estimate only. Personally, I really don't like the use of ATF or brake fluid. It contains some additives, such as zinc that is good for lubricity, but is not appropriate for quenching. The use of an oil suited for quenching is best, and will provide the best results. To some extent, this would include the vegetable oils, as long as the water is driven off from the oil.

 

 

Thank you, Scott. I will invest in good commercial quenchants when I'm more settled. I switched to ATF and started getting much harder blades than when I was using canola oil, but honestly the ATF makes me more nervous and I won't be using it forever.

 

Brian

[Mike Krall]

Brian,

 

You might be able to find chemistry for a brand of ATF/brake fluid through MSDS sheets.

 

The canola oil you mention, is it the scavenged "old french fry oil" you described in your first post?

 

Besides Park and Houghton Int. and Chervron (who now owns Texaco and offers at least some of their quenchants), I don't know of other manufacturers. I know MSC has a "fast" and "slow" oil but they obviously don't manufacture it and I've not had any luck with them in finding either how fast/slow it is, or the original manufacturer. There are a number of outfits out there who simply repackage... like my under standing Brownell's "Tough Quench" is rebranded Houghto-quench "G" from Houghton International. My luck getting hard information for rebranded quenchants from their sellers is poor and hearing from a sales rep., "Yeah, that should work for that", isn't particularly informative.

 

Scott,

 

Are there a lot of other manufacturers of quenchants in America besides the three I listed, or manufacturers who sell their quenchants here?

 

Mike

[Mike Krall]

...as long as the water is driven off from the vegetable oil.

 

Scott,

 

Seems to me driving the water off would be running the veg. oil above the local temp. for boiling water. Is there something about this I'm not understanding?

 

Mike

[Mike Krall]

Here is a thing I found interesting...

 

Part 1

 

Part 2

[Brian S. Pierce]

Brian,

 

You might be able to find chemistry for a brand of ATF/brake fluid through MSDS sheets.

 

The canola oil you mention, is it the scavenged "old french fry oil" you described in your first post?

 

Mike

 

 

Mike,

 

The canola oil I mentioned is indeed the same scavenged french fry oil. No doubt it has broken down, which would account for the incomplete hardness I experienced. I have no idea how long it had been sitting outside.

 

I understand why so many experienced smiths recommend working with known steel and commercial quenchants. However I think my trial-and-error experience has been beneficial and has served to refine my skills somewhat.

 

Brian

[kb0fhp]

Scott,

 

Seems to me driving the water off would be running the veg. oil above the local temp. for boiling water. Is there something about this I'm not understanding?

 

Mike

 

That is correct - but do it slowly by raising the temperature slowly. Hold at 180 for a while - if there are bubbles then hold there til it goes away. Raise it again a bit higher and repeat. Eventually raise to 220 or so and allow to hold. Allow to stop bubbling. then cover, and allow to cool.

[kb0fhp]

Brian,

 

You might be able to find chemistry for a brand of ATF/brake fluid through MSDS sheets.

 

The canola oil you mention, is it the scavenged "old french fry oil" you described in your first post?

 

Besides Park and Houghton Int. and Chervron (who now owns Texaco and offers at least some of their quenchants), I don't know of other manufacturers. I know MSC has a "fast" and "slow" oil but they obviously don't manufacture it and I've not had any luck with them in finding either how fast/slow it is, or the original manufacturer. There are a number of outfits out there who simply repackage... like my under standing Brownell's "Tough Quench" is rebranded Houghto-quench "G" from Houghton International. My luck getting hard information for rebranded quenchants from their sellers is poor and hearing from a sales rep., "Yeah, that should work for that", isn't particularly informative.

 

Scott,

 

Are there a lot of other manufacturers of quenchants in America besides the three I listed, or manufacturers who sell their quenchants here?

 

Mike

 

The heat treat industry is very fragmented. But Chevron has ceased production of QuenchTex A and QuenchTex B. They may have stopped production on others too. I would suggest that you contact a local oil distributor. Exxon Mobil produces some, and there are many foreign companies too - like Elf-Fina. They may have a house brand. You are correct about Brownell's. If it were me, and had to quench my work, I would stick to the major players, and ones that will provide some decent information up front. At least a data sheet that describes speed (GMQS), viscosity, and flash point. Cooling curves are also nice, but you have to take them with a grain of salt. There are many different ways to do a cooling curve. It is best if they are compared in the same lab at the same time. GMQS is a decent quantitative method of comparing oils.

 

Just remember, I may not be able to devote a lot of attention other than the time that I spend here. I am often dealing with orders of 1000 gallons and a lot more - like coordinating a 10,000 gallon order. I will also try and answer everyones email - but I also get about 300 a day from all over the world. It just may take me 24 hours or so.

[kb0fhp]

Here is a thing I found interesting...

 

Part 1

 

Part 2

 

Mike - those are decent articles by Dan Herring. Interestingly, Dan, and the people that he referenced (George Totten, Jan Bodin, Soren and Gajin), are friends of mine, and all serve on the Quenching and Cooling committee of ASM.

 

For those that are interested, there will be a course taught in Milwaukee in September on Heat Treating for the Non-Metallurgist. I will be the instructor. There will also be an EXCELLENT symposium on quenching following the course.

 

Links:

 

http://www.asminternational.org/heattreatedgears08/

 

http://www.asminternational.org/heattreatedgears08/edu.htm

 

The course will be a lot of fun - and you will learn a lot about the basic metallurgy, and how the "big boys" do it. /end of ad

[Matt Bower]

Scott,

 

Make video, put it on DVD, and sell it -- along with any accompanying handouts and similar materials. (Or tell the ASM to do so.)

 

I don't know how it works in the heat treating industry, but in my profession that's done all the time for continuing education.

[kb0fhp]

Scott,

 

Make video, put it on DVD, and sell it -- along with any accompanying handouts and similar materials. (Or tell the ASM to do so.)

 

I don't know how it works in the heat treating industry, but in my profession that's done all the time for continuing education.

 

I am not sure if they will - but it would be excellent. I know the quenching forum will be truly hard core technical. It will be a lot of fun!

[Mike Krall]

Brian,

 

I feel like you are right about learning a lot messing with "unknown" steel. In a lot of ways, I wish I had. My nature tends me to data collection, technical answers, dealing with known entities. It pretty well precludes doing the kind of thing you are with knives. Not having much of a facility for exploring the unknown misses me some of the art in making blades. Have fun...

 

Mike