My tools keep breaking. Is it the heat treat?

[bigfootnampa]

I have often experienced poor results from partial quenches.  IMO you’d be better off doing a full quench and then drawing temper differentially.  

You might also consider a few normalizing cycles to address grain growth BEFORE heat treating.  For beginners, grain growth is a common problem.  They tend to heat too much and move the metal too slowly... a good recipe for excess grain growth.  

I agree with all the advice above re oil quenching too... it is my standard method.  Water quenching can work well in certain situations... IMO it is best used by experienced smiths.

[anvil]

3 hours ago, MC Hammer said:

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

This is my technique with two differences. 

I always anneal the working end. I rarely, if ever, have a tool crack when using coil spring.

And, when the working end reaches the color I want, I put it in a can of water to maintain my temper. Then I let the struck end air cool. This is a poor man's "normalizing" on the struck end. 

I sometimes draw the struck end to a blue. This should be softer than your hammer yet hard enough to minimize mushrooming. Either way works.

I believe that anneal is critical. I believe that if you anneal coil springs that the microfracture deal is minimized.

[hanzosbm]

I'm a little confused by this.

Certainly, annealing would be ideal.  I just honestly don't know how I'd go about keeping the material at those temps for hours on end in a coal forge, at least not without it turning into something akin to watching paint drying.  

Also, you mentioned that when the working end reaches the color you want, you put it in a can of water to maintain the temper.  I'm assuming that this is after the quench, so you're basically halting the temper in the working end, but allowing the struck end to continue the temper?  And you mention it as the poor man's normalizing, but if this is being done AFTER the quench, and basically during the temper, I'm confused how this would normalize it.

Sorry, I'm still somewhat new to this.

[anvil]

No problem. When I did this at demos, I brought a can, or anything convenient,  of lime with me. I forged the tools and annealed in the morning. Just bring  the whole tool up to critical and place it in the lime after forging. It will be cool enough in a few hours or after lunch for sure. Then heat treat.

Yes,  harden your tool, both ends, not the middle, do a quick polish, then watch the Colors run. This is tempering. When the working end reaches the color you want, place it in a half inch or so of water to "freeze" it at the color you want. Then when the struck end reaches the color you want, put the whole tool in water, or, if normalizing, just leave the tip in the can and let it cool. If you are making a short tool like a center punch, just bring the whole tool to the proper color and heat treat the ends. If you are making a punch, say 14" long, then only forge and heat treat the working ends, not the middle.

Placing the working end into water will not cause a crack as your whole end should be beyond a dull red.

Hope this helps.

[MC Hammer]

I suggested the water process because he was working with water.  I personally would rather fool around with oil because water is quite a harsh quench, but those that use water claim it does a superior job.  I guess I'll find out.  Coil springs are easy to come by and cheap at the scrap yard.

Hanz - it sounds like your instructor wasn't really giving you clear instructions on the tempering process.  It seems to me that your breakage issues are with this area.  Try oil, and try the water methods mentioned above and see which has the better results for you.  I'm not sure the high grade quenching oils will have much of a benefit for you if you are making tools.  Like many say here, start with easiest and cheapest and work up from there.  

[TwistedCustoms]

16 hours ago, Frosty said:

Real Quench is a brand name as well.

Thanks Frosty, I'm not familiar with that one but I like the name!

 

15 hours ago, ThomasPowers said:

I wouldn't consider Parks 50 as a "general duty quenchant" its a "extremely fast quench oil" so at the far end of the oil quenchants bell curve.

Granted. I consider it general duty because it covers most of my production but my statement was not an accurate generalization.

[anvil]

1 hour ago, MC Hammer said:

I suggested the water process because he was working with water

To be clear, i quench(harden) coil spring in oil, but I use water to stop the color run. 

[Frosty]

4 hours ago, hanzosbm said:

Sorry, I'm still somewhat new to this.

Don't be sorry, nobody is born knowing this stuff and it's a life long learning curve. I just grabbed this post of yours so I could ID who I'm talking to to start with.

I misread your OP and thought you were teaching, not taking classes. My bad time to change gears some. You can water quench spring stock it's just trickier judging the temperature of the tool. One of our guys water quenches spring stock all the time but he's been smithing professionally for a good 40 years. I use oil. 

More importantly do NOT think any of this discussion is directed at you. Proper heat treatment can be a hot topic, loaded with opinions from all over the spectrum: Pro bladesmiths and published authors, to guy's who's only qualification is what they heard on the internet. When you're heat treating on the level of most home shops you aren't working to high specification, there has to be room. I don't know many folks with the kind of ovens and kilns necessary to gain the maximum qualities of the steels. Lots of different steels and wide margins of precision mean there are a numbers of methods that "work."

I agree, specific info can be a real bear to find on Iforge. The onsite search engine stinks. Use the one you usually do and add Iforge to the search terms is much more effective. Even then the site is more of a living journal than a text book. It'd be SWEET indeed if it were "properly" organized like an encyclopedia but that would take a couple generations with what's archived now. It's just not possible, the volunteers who try to keep herd on this gang of cats have their hands full now. 

I don't like how some of it is organized or managed but I'm not going to volunteer so I take it as it comes with the occasional suggestions. I'm a TBI survivor and frankly couldn't do the job. My memory is too scattered and my attention span is: . . . Ooooh look SHINY!!

Frosty The Lucky.

[Steve Sells]

McMaster sells the 11 second oil for less than $20 for a gallon delivered, for a ONE GALLON JUG last time I topped off the tanks

and yes you can buy 55 gal drums if you wish, the point was it aint that much for a can of the real stuff, my normal tank only holds 7 gal, and the sword tank 2.5