Jump to content
I Forge Iron

My tools keep breaking. Is it the heat treat?


Recommended Posts

I do all of my forging at a museum that teaches large numbers of students at a time.  One of the classes was on tool making (punches, chisels, whatever, it was basically teaching heat treating) and at the time, I made a chisel.  After a few days of use, it broke about halfway up the blade.  Okay, so, I'll make another.  Same thing happened.

The material used was old coil springs, and the method was very basic; straighten it, taper it, shape it, go through a single normalizing cycle, quench the tip in water, allow the heat in the handle to temper the tip.

I think this method was being taught as the most basic way of going through the process, and many other students used this method and seem to have tools that survived (although, I didn't go around and ask them all).  The school doesn't have quenching oil, and the coils, while spring steel, are of an unknown alloy.  My thinking is that water is too fast of a quenching agent and it's causing a stress crack.

So, first of all, does my theory sound likely?  Secondly, since the school doesn't have quenching oil, and I don't have the ability to get the tool to a critical heat at home, I was thinking of bringing a small jar of canola oil with me to the forge.  Obviously, I'm guessing a bit at what the right type of quenching medium to use is, and canola is not ideal, but I'm getting tired of remaking tools after a few days of use and I'd rather not have to buy them all.

Link to comment
Share on other sites

OIL!---Use more than a small jar; get a gallon at least.  Get a metal container to put it in and a metal lid to cover it when it flares up! Make sure you move the item up and down in the quench liquid too (water or oil---holding it at a single point does tend to promote issues---even 100+ year old smithing books discuss this!)

If you can access a blow drier and a charcoal BBQ grill you have the ability to get to critical temp at home---shoot you could skip the grill and use a hole in the ground...

Link to comment
Share on other sites

21 hours ago, ThomasPowers said:

OIL!---Use more than a small jar; get a gallon at least. 

Well, transferring a gallon of oil with me to the forge isn't very practical, but you bring up a good point about a BBQ grill.  I recently moved, and even though the apartment complex says no grills on the balcony...I do it anyway.  That being said, your point about flare ups are a concern while standing on a wooden balcony 4 feet from the building.  I'll have to give that some thought.

 

21 hours ago, Kevin Olson said:

 You probably have spring with micro stress cracks from years of flexing.

That's what the instructor mentioned, but honestly, I wasn't sure if he was just saying that because they only have water or if he was being honest.  I guess I can keep trying.  In a perfect world, I'd have my own forge, get new stock to make the tools from, and use the exact quenchant, but that's not the situation.  It's just frustrating to spend the time to forge it and go through the whole heat treating cycle only to have it break after a few uses.

 

21 hours ago, Buzzkill said:

This kind of cracking is also more likely if you are too hot when quenching.  That can promote large grain growth

Hmmm, okay, that's good to know.  I can definitely get a magnet to test, but as a follow on question; is too hot an issue only during the quench?  In other words, if I'm forging it to shape under very hot conditions, is that also a concern?  I generally try to forge as hot as possible (without burning the material of course) to make the work easier, but if it's causing problems, I can back off and apply more elbow grease.

Link to comment
Share on other sites

With mild steel it's not as much of an issue, but some alloys should not be forged above specified temperatures.  I've had pieces of coil spring literally fall apart when using a coal forge and getting them too hot.  If you burn the steel it will be very weak and often has an appearance similar to cottage cheese where it was burned.  If that happens the steel is junk and should not be used for anything, especially a tool that will be struck.  So, yes, you can have too high of a temperature when forging.

Link to comment
Share on other sites

Okay, that's good to know about some particular alloys.  

I've certainly been guilty of burning my steel before, (I quickly learned that the crank on the blower shall not be in motion unless I am actively watching the fire.  Chatting and cranking do not mix) so I'm at least familiar with the cottage cheese/sparking in the fire you're talking about.  My concern was about forging below that temp, but above critical, which it sounds like can be an issue with some alloys.  Of course, not knowing exactly what these springs are made of means I can't say for certain.  I guess to be safe, I could just forge them cooler.  It'll mean more whacky whacky, but taking 10 heats for a tool that'll last a lifetime is better than 3 heats each time for a tool that has to be remade every few months.

Link to comment
Share on other sites

Talk to a spring shop about buying drops of new spring steel. A little PR will do wonders, a box of doughnuts in the morning, a nice card holder for the secretary, etc. and don't forget to tell them you're instructing at a museum they might be able to deduct the scrap price as a donation. Heck, they might be willing to give you a stick for the deduction. 

Until you get your heat management skills up to it don't forge spring steel above medium high orange, it has a significant percentage of molybdenum which can be air hardening. 

A thing to take into account during heat treating things like punches chisels, etc. is the THIN sections heat faster than thick sections. If you're bringing the whole chisel to critical temp then the blade has been that hot a long time before you quench. Just heat the blade and quench it. Then temper it by heating the struck end and watching the temper colors run. They run very fast in spring steels so be ready with the water to stop the temper.

You don't want the struck end of tools hard so leave them as normalized, they'll be much less a chipping hazard.

Quench in oil, the museum can afford 5 gl. of Canola and a steel container with a lid, money isn't THAT tight. Point out it isn't safe to make struck tools from salvaged steel and water quench it, THEY have the liability issue. Fire safety is the same thing, its their liability. 

Frosty The Lucky.

Link to comment
Share on other sites

My relatively novice two cents: 

There's nothing wrong with canola oil as a quenching oil - it's cheap by the gallon and food grade, so not toxic. Xxxx, when I was first filling my AMMO CAN quench bucket (a large one that holds a little over 3 gallons of oil), I left it unattended while going into my shed to get another gallon of oil, and came back to my dog lapping it up out of the ammo can! No harm though - it was fresh, unused canola oil. 

Maybe $30 for an oversized ammo can and a few gallons of oil (yes, canola, etc are perfectly fine - whatever is cheaper) and you're in business. The ammo can will have a handle and should be water-tight, so you can even transport it from home to the forge and back if you don't want to leave it there. 

Edited by Mod34
Edited for inappropriate language
Link to comment
Share on other sites

That would be great, but you say that as though it's clearly labeled and easy to find. 

There is no sticky with any label referring to "real quench oil" under general heat treating info. The only stickies there are about the evils of motor oil, general heat treat information (which does not mention real quench oil, at least in the initial post), one about a tempering oven, and one about a heat treater's guide. 

Or one could look under the "all stickies here" sticky, which also does not have a sticky relating to "real quench oil". 

I don't mean to sound like a smartxxx, but when you say things like " oh, just read XYZ" and the article on XYZ is not easily or intuitively located, such guidance is pretty much useless. 

Can you explain where the reference to real quench oil is? Because if it is under the Heat Treat Information sticky, it isn't easy to find. 

Link to comment
Share on other sites

"real heat treat oil" could be taken to mean a specified brand or formulation as specified by a manufacturer for a specific alloy which information would be listed in the published heat treat data for a given alloy. Or it could mean a general duty quenchant such as Parks 50. For most hobby smiths who aren't doing precision heat treat exactly to manufactures specs we can get good, repeatable results with food based oils like canola, vegetable oil or peanut oil. All of which are "real" quench oils as long as they cool slower than water. To maximize the potential benefits of a higher grade of steel you would need to know the viscosity, cooling rate, boiling point, flash point, ideal oil temp, all of which is pretty much meaningless if you are then going to toss your hardened work into a thirty dollar toaster oven or temper by eye. More sophisticated alloys need tighter controls at every step to maximize their hypothetical potential. For simple steels and some low alloys water and canola oil will see us through.

Link to comment
Share on other sites

38 minutes ago, TwistedCustoms said:

"real heat treat oil" could be taken to mean a specified brand or

Real Quench is a brand name as well. It says so right no the can. Heat treat oils do indeed say what they're for on the label in addition to a lot of specific info your average person couldn't use.

We used to tell folks to buy heat treat oil but too many argued that they wanted to quench their stuff not heat treat it. Trying to explain was eating our brains.

I tend to take things like this too casually been doing it too long to remember what the first time I heat treated something was like. Still, I have to consider the OP in this thread, the fellow is TEACHING other folks without some pretty basic knowledge. Disagreeing about which really general term is best misses how basic the knowledge lack really is.

Frosty The Lucky.

Link to comment
Share on other sites

Good Morning,

Start slow, learn from your breaks and errors. There is a reason most Smith's have a "Bish Pile". You have to do your own research. Don't expect one answer to be true for all applications. Buy some cooking oil from your Grocery Store and try it.

Quenching oils all have different "Quench Rate". How many seconds to cool something from 1000F. Brine is faster than water, Oil is slower than Water. If you are getting the piece too hot before quenching, all rules go out the window. Simple job, start at the beginning.

Neil

Link to comment
Share on other sites

13 hours ago, Frosty said:

I have to consider the OP in this thread, the fellow is TEACHING other folks without some pretty basic knowledge. Disagreeing about which really general term is best misses how basic the knowledge lack really is.

Unless I read it wrong, the OP is not teaching, but rather taking classes, so being "without some pretty basic knowledge" is understandable. 

For the purposes of this discussion, I don't think there is any disagreement about which general term is best, but just wondering what Steve means when he says "do it right" and buy "real quench oil", suggesting that anything else (canola, peanut, motor, etc) is doing it wrong. Except instead of providing a clear answer, in good curmudgeon form, he references a pre-existing post or article that is not readily findable (or maybe I'm just dumb or slow, Masters from Harvard notwithstanding). 

I know I fully expect to be banned for a while for daring to quibble with curmudgeons, but I think Steve's post is about the most un-helpful thing I've read this week. I mean we all expect a degree of grumpiness from the old-timer curmudgeons, but come on...

Smiths for centuries and plenty of people today successfully use vegetable oils and a variety of other media that are not commercially produced specifically to be high-performance, specific-purpose quenching oils.

Bottom line for the OP: yes, water as a quenchant is probably setting you up for failure, and there are a multitude of inexpensive and "field expedient" options out there that will likely solve the problems you are experiencing. 

And with that I bid you good day (possibly permanently).

Link to comment
Share on other sites

If you have bothered to read the HT sticlys you would know food oils were never designed for quenching,   McMaster- Carr 11 second, and Parks 50 and AAA were designed just for that, Sorry if your MA gets in the way of understanding , I wont waste your time any more.

and contrary to what a few people think, you dont get banned for disagreeing with us

Link to comment
Share on other sites

Wow, ok............well back to the OP's question.  There's a lot to quenching and heat treating.  I'm no expert at all, but there are many different ways to accomplish good results but because you used water I'll tell you what I know about it.  I watched a guy make a punch and he got it up to critical non-magnetic temperature then he quenched the struck end first, then the punching end, quickly shined up the punch end letting the heat left in the middle to soak down to the punch tip until it was the correct straw color he was looking for then he quenched the whole tool in water.  I'm guessing the struck end tempered to about the same hardness as the punch end because you wouldn't want the struck end too hard or it could chip and cause injury.  This is the way he was taught to do it by the master blacksmith he apprenticed under.  He was using coil spring steel.  Try it since you are working with water.  I've always heard to quench punches and tools with oil.  When I have time to start making all the punches I want to make I'll probably try each method to see which one works best marking the water quenched ones with a "W" and the "Oil" quenched ones with an "O".  After a while using them it will become evident which I like better.

Mr. Sells makes a valid point.  There are quenching oils in the good, better, and best categories with him naming the better or best ones.  I think for those engaged in serious bladesmithing, they want the optimum results.  Makes perfect sense to choose better and best quenching oils.  I think that's what Mr. Sells is getting at.  I see nothing wrong with food grade oils and they are probably categorized as good quenches that get the job done.  Each must choose a quench according to desired results and need in accordance with the steel being quenched.  If you do high end knives for a living, maybe peanut oil is not the best choice, but if you are making a chisel for your own use it'll work just fine if you do it right.  Water was used for a very long time too.  Again, I'm no expert so others can feel free to correct me.   

Link to comment
Share on other sites

4 hours ago, Steve Sells said:

If you have bothered to read the HT sticlys you would know food oils were never designed for quenching,   McMaster- Carr 11 second, and Parks 50 and AAA were designed just for that, Sorry if your MA gets in the way of understanding , I wont waste your time any more.

and contrary to what a few people think, you dont get banned for disagreeing with us

Steve, 

First, my apologies for getting a little curmudgeonly/grumpy myself last night - long day. Let me back up. 

I've seen several places where you refer people to the heat treat stickies about quenching oils, but nowhere can I find them, and I consider myself not dumb or unsavvy when it comes to computers and forums. There are only four stickies under heat treating general discussion and none of them deal with quenchants. Nor are such references under knifemaking classes, etc. SImply put, I can't find them, and if I can't, there a decent chance some other folks may not be able to either. 

I totally understand that you senior smiths here with your massive amounts of knowledge and experience get tired of saying the same things over and over again, but perhaps a better approach might be to provide a link or two, because again, I'll be xxxxxx if I can find the stickies to which you refer. 

Of course we novices know that food oils were not made for quenching, they are made for...food. But you know probably better than most of us that quenchants manufactured specifically for that purpose are a very recent invention in the timeline of smithing, so there have to be acceptable substitutes for the beginner. 

Anyway, again my apologies for being a little grumpy with you last night - I just got frustrated at the suggestion to refer to references that should be readily findable (especially if they are fundamental information), but are not. Again, links would be helpful. 

Cheers!

Link to comment
Share on other sites

Please after you get the information, make a separate post so we can make it a sticky. 

One of the first quenchants I use is air. Then I progress to harder and harder quenches. Of course as soon as you change to another piece of metal stock, it starts all over.

Link to comment
Share on other sites

Wow, looks like a lot of activity on this.

To settle one issue, I am a student at the museum, certainly not an instructor.  Regarding quenching oils, I would 100% agree that something purpose built for the task would be ideal.  The reason I originally brought up the idea of vegetable oil was for a few reasons.  First, at the moment, the only items I need to heat treat are the occasional tool, so, assuming the darn things quit breaking, it'd probably only need 3 or 4 over the next year or so.  Sourcing and spending the money for proper heat treating oil, which I assume would come in pretty large quantities, and storing it in my one cramped 1 bedroom apartment with a wife would probably wouldn't be thrilled about it, just to see if that is in fact the problem I'm having with the tools I have wasn't the ideal scenario.  That doesn't mean that it's not the 'right' way to do it; it is, but my hope was not to go 'all out' right away if it wasn't necessary.

I looked up the cost of quenching oils, and, yeah...they ain't cheap.  Granted, they'll last a long time, but for the few things I'm doing right now, it would be cheaper to just buy the tools.  I'm sure the day will come when I'll be able to have my own shop and at that time, I'll spend the money, but for now, vegetable oil is about as far as I'm willing to go.

On that note, the method we were taught (in water) was to just quench the tip and then allow the body of the tool to temper to the desired level with the residual heat.  Would it be possible to just quench the tip, leave the tip in the oil while the body air cooled, then pop the whole thing in the oven to temper the tip?  I was having a hard time getting a good look at the temper colors in the tip and then constantly going back in the quench to keep it from over tempering, so I was thinking the method I described might be easier, but I didn't know if that would cause too much stress right at the point where tool transitioned from being oil quenched and air quenched.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...