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Hawgdirt

What happened to my punch?

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 Just wondering where I might have gone wrong.  I was punch a hole and it just snapped in 2. Third picture is what I made out from, looks like pto shaft which I thought was hard metal. When I hear treated it I got it to a dull red and stuck about an inch of the tip in water.

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There are people with much more knowledge than me on here but I'm here so I'll toss out my thoughts and maybe learn even more from other's responses:

    A number of issues could have caused that.  You may have worked the metal too cold. It looks to be a small drive shaft for a snow blower auger or something similar and so it would need to be pretty hot when worked.  Also, it could be a funky alloy and not 4140.  Either way, if you didn't normalize it a few times before hardening it might have stress points that are doomed to fail.

You should have quenched in oil, particularly because it is mystery steel.  There is a chance you created a fracture in its structure when you put it in the water.  The best thing to do would be to make a small test piece and assess its properties by quench testing it in oil, the water if oil doesn't harden it. (Test with a file).   Then run temper colors down its length and test where it no longer fractures in your vise.  That's the color you aim for in your final temper.

Speaking of which, you left out any description of your tempering process.  If you didn't temper it that's likely your problem.

 

because it broke so high up I'm leaning towards the idea that you had a major crack in its structure from hitting to cold or from the water quench.  

 

There is so much to learn about heat treating.  You've just had a great learning experience.  I know I've had mine.

 

Lou

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You do know that Hard means Brittle when you are talking about steel. (Save for some very odd and rare alloys).

So did you slide it up and down during quenching to prevent cracking at the air/water interface?

Did you make sure it was a water hardening steel before quenching it in water?  Many steels will develop cracks when quenched in water and require oil or even more gentle quenchants.

Did you temper it? If it gets quenched to harden; tempering is pretty much MANDATORY! (at least a snap temper)  If you did temper it to what colour and how did it react to a file afterwards?

And it's likely you had more than 1 issue with it; the primary one being that you don't know how to work and harden high carbon steels.

Note PTOs are generally tough rather than hard metal as toughness is needed not brittleness. (My guess would be something like 4140)

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Hawgdirt: You need to do some reading about working with high carbon steel. Chances are how you heat treated it would've had problems almost no matter what alloy it was provided it had enough carbon to harden at all. 

On the upside I don't see excessive grain growth in the break which is a good sign. Not good enough to save it from breaking but a good sign anyway. It's common to see breaks like this where the steel has crystallized severely from being kept too hot for too long without sufficient hammer work to refine the grain. (crystal structure)

A few hours of reading and taking notes WILL save you many hours of work and repeated failed tools in future. 

Frosty The Lucky.

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Thanks for the replies, guess I need to look up some information,  I don't even know what tempering is.

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8 minutes ago, Hawgdirt said:

Thanks for the replies, guess I need to look up some information,  I don't even know what tempering is.

It's the controlled softening of hardened steel to prevent brittleness while providing the desired properties, hardness, springyness, etc. 

It's a darned involved process and not something to wing. Iforge has a pretty large heat treating section.

Frosty The Lucky.

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There are a number of heat treating steps with differing results; the major ones are 

Annealing: makes steel soft

Normalizing: removes stresses from steel, makes steel harder than annealing but softer than hardening, it  will be tougher too

Hardening: heating above the critical temperature for that alloy and then quenching in the PROPER quenchant makes steel as hard as it will get and therefore the most brittle too.

Tempering: heating to a much lower temperature and trading some of the hardness from quenching for toughness.

Note you have to use an alloy that will profit from these steps; example very low carbon steel will not harden even when quenched in cold water.  Some high alloy steels are very difficult to anneal or normalize as they harden in air.

If you don't know about tempering you shouldn't be hardening steel!  *ANY* good blacksmithing book will explain hardening and tempering in it as one of the basic steps in smithing of higher carbon alloys. Please don't go with what Hollywood and Fantasy books and games tell you about smithing. Learn the real stuff!

 

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I found this article very instructive when I started making punches and such.  I think it is a great place to start.

http://www.bamsite.org/tips/heat.pdf

Enjoy learning about what treating.  It really was eye-opening and exciting to me when I began to learn exactly how complex steel was.  Heat treatment opens up limitless possibilities for what you can do with a given steel (assuming it has carbon enough to harden even a little).  It also opens you up to a world of errors and hard lessons.

Lou

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37 minutes ago, Lou L said:

I found this article very instructive when I started making punches and such.  I think it is a great place to start.

http://www.bamsite.org/tips/heat.pdf

Enjoy learning about what treating.  It really was eye-opening and exciting to me when I began to learn exactly how complex steel was.  Heat treatment opens up limitless possibilities for what you can do with a given steel (assuming it has carbon enough to harden even a little).  It also opens you up to a world of errors and hard lessons.

Lou

That's a handy link, thanks for bringing it to my attention. 

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I appreciate all the responses, good thing I was trying my hand at heat treating or I wouldn't have learned anything. 

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I learned long ago that I will never live long enough to make *all* the mistakes; so I try to avoid making the well documented "easy" ones and specialize in the oddball if not outre ones. Remember the old saw about methods of learning and the electric fence!

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I don't bother heat treating my punches for hot steel, Its a waste of time as it will lose its temper anyways, and yes I remove it each hit. they hold up just fine, and it doesn't take but 15 minutes to make a punch.

                                                                                                                        Littleblacksmith

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Depends on the alloy; some of the high alloy steels the tempering temp is in the glowing range!

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true, I should have said I don't bother heat treating punches made from coil spring, very good point! Now, If I was to make a punch from H13, I think I would.:)

                                                                                                             Littleblacksmith

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Some time ago, a fellow smith made a fuller out of a railroad spring clip.  These are fairly high carbon, and must be treated carefully.  He had an accident in which the tool shattered while he was using it.  He said it just sort of crumbled, and he was not injured.  He gave me the other piece from the same spring.  This was very scary, so I wasn't going to use it without looking it over very well.  First, I determined that the tool had been tempered, since a file could cut it easily.  Then, I looked at it very carefully.  There was a tiny crack where the sharper part of the curve was straightened.  I figured that it would be a good idea to file out the crack.  Anyway, every time I thought I had gotten through it, there still seemed to be a little bit left.  Finally, it became clear that the crack was very deep.  I eventually ended up filing almost half the thickness away before getting to the bottom of that crack.  Eventually, it became more driven by curiosity than the desire to salvage the tool.  Despite the huge notch in the middle, this has become one of my favorite fullers for light detailed work.  It has lasted for many years and has produced hundreds, if not thousands of items, most of which sold.

Careful with salvaged steel.  It is more fun than it is economical.

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On 5/15/2017 at 10:41 PM, Lou L said:

I found this article very instructive when I started making punches and such.  I think it is a great place to start.

http://www.bamsite.org/tips/heat.pdf

Enjoy learning about what treating.  It really was eye-opening and exciting to me when I began to learn exactly how complex steel was.  Heat treatment opens up limitless possibilities for what you can do with a given steel (assuming it has carbon enough to harden even a little).  It also opens you up to a world of errors and hard lessons.

Lou

I read that off, and while I was able to harden and get the colors to run, I was a little confused on the critical temperature. I was using a welders magnet and tested it before going in the fire to make sure the magnet stuck well. After putting the metal in the forge I tested it at different stages. Either I'm doing something wrong or the metal im using has a very low critical temperature. It wasn't even glowing dull red and it wouldn't stick to the magnet. I thought metal had to be very hot to become non magnetic.

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Aside from the light issues Thomas pointed out (the most likely problem)...different alloys reach critical at different temperatures.  In fact, the magnet test isn't even truly accurate.  For most people it is "close enough" but for some only a heat treating oven and the specs for the particular alloy will do.

Just keep testing tabs of material then perform the break test.  In no time you will have it down.  Heck, I haven't done it for a while since I practiced repeatedly.  I should probably do a few myself.

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It was very neat to watch the color run and to see that it was hard, did a file test and didn't really cut like it did before had. Was able to hear and feel the metal crack being put in water so that was good learning material. As far as ambient light goes, my forging area is outside under a lean to and sun was shining. I reckon if I ever start forging quality items ill have to heat treat at night.  I know it's frowned upon by some people,  I've read mixed reviews about using motor oil but that's what I have on hand right now. 

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I'm afraid of using motor oil...but at least you are outside and have maximum ventilation.  If you want free then make friends with a small restaurant and get their used oil.  You can buy cheap peanut oil at wholesale places.  There are tons of threads on quenchants here.  You will find something that you like and can get with some light reading.

 

I can connect to that feeling of file testing.  Even though I feel confident the file is going to skate across the metal after the quench I still get a little charge out of it.

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Used peanut oil can often be sourced right after Thanksgiving as many folks buy a Turkey fryer, use it once and then discard the oil and buy more the next year. (or not, I've sourced good high pressure propane regulators off of yard sale turkey fryers...)

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Some restaurants will let you have their used fryer oil, but make sure you get it from them before it goes into the used oil bin out back. A lot of times, they'll have a contract with a waste oil removal company, and the oil becomes the property of that company the moment it enters the bin.

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