Adam R

4142 Hammer Failure

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I have been working on a hammer head while I try out my new gas forge. The material is 4142 1 1/2" square stock. I started with a 2lb. piece with 2 offset holes drilled to help guide the punch. My wife held the stock and punch while I swung the sledgehammer. The hole punched well, but I didn't have a hardy hole. My current anvil is a 3x8x13" piece of S7 with a couple different radii cut and shaped on the ends similar to Brian Brazeal. If you're wondering why the odd alloys, there was a crazy sale I got in on with our local group.

I took it to a class I was helping with, and worked on drifting it during the lunch break. The anvils were too high to get a good swing at, so I didn't get very far. I decided a striking anvil would be helpful for all the normal reasons but especially the finished price of under $75 for supplies. Drifting the hammer eye proved fairly easy with this.

The faces of the hammer were upset slightly then shaped into a rounding hammer similar to a Nathan Robertson (no fullering). This is the style that the MN Guild teaches in a class I took. After final drifting and shaping. I normalized it three times with the last time leaving it in the forge after shutdown to cool. I ground the faces to 220 grit before hardening. Finished weight was  1lb. 13oz.

I heated the head up slowly from a cold forge turning it over for even heating. Then quenched it in used fryer oil, moving it constantly until it was cool enough to handle. I tried testing it with a file to check for hardness, and it didn't seem very hard. The file didn't take much effort to scratch the metal not just take off the black color. I had read conflicting reports about oil vs. water quench with 4140/42 (most documents say the two steels can be used almost interchangeably). I reheated the piece and quenched in water. Which seemed to harden much better. About this time my wife was getting home, and my little guy woke up from his nap. I was doing some quick clean up, and the hammer head fell on the concrete patio.

After I helped with a couple things and ate lunch, I started to wire brush the piece before a cleanup grind to show temper colors, and noticed a fine crack through the rounded end.

There are some pretty obvious things that I would do differently, (slow down, don't drop it, and don't wait to temper for more time than it takes to get a shiny enough surface to see colors) but I have another 4'+ of the stock, and don't want to repeat this learning experience. I have done more research here and online including spec sheets, and don't think I did any forging outside of the appropriate temp ranges. The crack is a nice clean gray color not black as I have heard might be a sign of forging outside proper temps. I have seen some people say on IF that 4140 doesn't really oil harden very much past what you would get with tempering it to a straw color anyway. So I am wondering if I got as good as I can with a not quite awesome oil quench. Along the same line, did I really do the wrong thing with the water quench. This is only my second time quenching anything in oil.

I have read in Mark Aspery's first book that he recommends using 4140 for most punches/chisels and using a localized water quench using residual heat from the bar for immediate tempering. I know hammers and punches have very different dimensions, but I am wanting to make both at present so I thought I would throw it into the discussion. If he covers this in his other books, let me know. I am getting those for Christmas (SSSHHH!!! don't tell anyone I know). Sorry for the long post, but you all tend to want as many details as possible for the best advice, which has been greatly appreciated.

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13 hours ago, Adam R said:

 

 I had a bit of trouble sorting all the non H/T stuff form your post so I could see what you were asking about.  I still have no clue why you normalized 3x then annealed,  that left large grain in the steel that you later tried to harden.  Because you got the grain large by annealing, to make the steel easier to grind, you really needed to cycle afterwards to reduce that grain size, increasing the hardenablity

You didnt say how you hot you got it, or how you made sure it was hot all the way through. but if you read any of my pinned H/T posts, you would have known to heat all the way through and if it doesnt get hard in oil, too try Brine.

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Annealing after normalizing?  Seems a bit backwards.  Also having a clean crack mainly means that it happened recently and so was not reheated and oxidized or had time to rust or had oil oxidize in it.  So happened during the water quench or when it accidently dropped would be my guess.  You did go ahead and temper it right?  Of so; can you grind deeper than the crack and make a lighter hammer or make that end into a diagonal pien?

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Steve- Sorry for the somewhat rambling OP. I wasn't sure if I would get questions about the number of heating cycles or how it was forged. I was thinking my problems may have been more related to the steel I was using. I had looked at all of the 4140 cracking/problem posts that I could find. I looked at more of the general HT discussions as suggested and see the points about the annealing process. I had read the HT pins some time ago, and obviously should have read them again. I didn't find a pinned topic that included the brine info, but I will keep looking. There was one post that was a round up of good beginner articles with broken links. Thanks for being patient with another newbie.

Thomas- The crack goes through to the eye on the rounded end. I may try to salvage the flat end, and turn it into a wire handled flatter. I need something like that anyway. Would you suggest Normalizing before cutting through the eye to remove the damaged section, then forging it?

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How are you going to cut it?  With a hack saw I would go with an anneal first.  If with an angle grinder then If it was well tempered than I would not normalize and just cut.  

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I milled a large v-block deeper and then rounded the base of the  V with a ball nose, welded a 1" square x 3" hardy shank and I use that to hold the work piece while I hammer out the eye.  Saw Glen do it from GS Tongs.   For me, this works great and I can do it all by myself.  Now a days I use a 20T press I built with an eye punching die.  Make top tools and hammers on the quick!  Add a few fullering dies and Shazzam! Im done, ready for handle.  too easy.   Might want to temper next hammer back  right after quench.   Good policy.   Reading your post, it appears you quenched it, then dropped it and as it was brittle and without temper it cracked.  

Check out Nate at jack pine forge and / or give em a call, great guy that makes wonderful hammers.  He can lead you down the path you seek.   Good luck. 

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Lots of things can go wrong when heat treating. My spec sheet says to harden at 1525/1575F which by eye, is a bright red just hotter than the cherry red ranges. Above that, you're creeping into an orange heat, which would be too hot. Oil should work but should be pre heated to change its viscosity, which speeds up heat abstraction. The oil bath should be agitated by stirring before immersing the 4142 work piece.

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From what I've read about HT 4140 it depends on the thickness of the piece as to weather to use water or oil for the quench.  If the piece is 2" or more use oil, anything less use water. 

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57 minutes ago, Kal said:

If the piece is 2" or more use oil, anything less use water. 

Im afraid you have that backwards. Thinner cross sections need a slower quench, so you use oil. 

 

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My specs call for oil quench and hardening  temp is as Frank stated above.

Also, and not meaning to start a debate but,, there it is ;) literally every spec sheet and source I have lists the ht sequence as I learned it long ago.

Forge

Normalize

Anneal

Harden

Temper

Verhoeven describes why this is so in his book as well.

Basically and from memory here's why from his book

1: all data in the ht charts are based on a fully annealed piece. The farther off from fully annealed the less likely you are to match the predicted results.

2: as a general rule, grain growth occured at a higher temp than either normalizing or annealing.

3: as a general rule the temp for normalizing is higher than that for annealing.

Thus, grain growth is not going to occure. So "healing" grain growth from high temps and forging happen at a slightly higher temp than annealing. If you anneal first, then normalize, you will lose your anneal. 

Thus the recommended sequence above.

Any arguments must be directed to Verhoeven.  I am but a mere blacksmith. And the above has rarely failed me. ;)

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Mr. Anvil,

Could you please mention the title of Verhoeven's book?

Thank you.

SLAG.

 

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Since the Dr V paper I have is 105 pages long would you mind listing where it is that lists normalising 3x then annealing.  This process you listed is normalising to get the grain small then allowing it to grow by annealing also where did you get the normalising is at a higher temp than annealing?   This is opposite to what I wrote in my book and I used Bain and Dr V as a reference 

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I'm with Steve on this one, though a lot is dependent on what level of simplification of terminology you are using for the different processes that make up the overall heat treatment process.

2 hours ago, anvil said:

Forge, Normalize, Anneal, Harden, Temper

I  learned a different sequence for hypoeutectoid steels like 4140:  Forge, Anneal (preferably spheroidal at very specific maximum temperatures and cooling rates), Grind/Drill, File..., Normalize, Harden, Temper. 

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hmmm......seems I have had success with forging the hammer to shape, punch the eye, drift to size, heat to nonmagnetic, quench, heat w/ torch in and around the eye 'til the colors run.....fully quench at a light bronze on the faces.  All in a nonstop sequence, one session one hammer head.

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19 hours ago, JustNick said:

Steve where would one find your book I have looked (quite Quickly) and could not find it ?

"Metallurgy of Steel for Bladesmiths & Others
who Heat Treat and Forge Steel"

Hits a good read, but not an easy one.

You should not have a problem finding it as a PDF or hard copy. I have both. I seem to absorbe more from a real book

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did you even read what we asked? I asked WHERE in the paper and Your quote is Nick asking where to buy my book,

You are not paying attention, which is also  the problem with your first posting about this, you did not pay attention.

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21 hours ago, Steve Sells said:

Since the Dr V paper I have is 105 pages long would you mind listing where it is that lists normalising 3x then annealing.  This process you listed is normalising to get the grain small then allowing it to grow by annealing also where did you get the normalising is at a higher temp than annealing?   This is opposite to what I wrote in my book and I used Bain and Dr V as a reference 

Dr V does not say to normalize 3 times, nor did I. He very specifically stated to normal once and more than once is wasted time,, unless specifically called for by the specs.

I will give it a try and look for that.

 

However, a good counter question to that is why do both Dr V and nearly all spec sheets list the heat treating process as I listed above? Specifically normalizing first. 

 

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no one says to normalize then anneal then harden. Except for your statement above

It is standard to normalise (to relax stress and make grains small) then harden,  Annealing (which makes grains larger and easier to move) is for when we have to work the metal, then we normalize again after we finish to get the grains small again

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1 minute ago, Steve Sells said:

did you even read what we asked? I asked WHERE in the paper and Your quote is Nick asking where to buy my book,

You are not paying attention, which is also  the problem with your first posting about this, you didnt pay attention.

My bad, I had a message and was quoted. I chose the wrong post.

But for a quick check, the heat treaters guide companion lists normalizing temp to be 1600f

And annealing lists two specific situations with temps being 

1: 1555f and

2: 1330f.

Like I said, "slightly less than".

 

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44 minutes ago, Steve Sells said:

no one says to normalize then anneal then harden. Except for your statement above

It is standard to normalise (to relax stress and make grains small) then harden,  Annealing (which makes grains larger and easier to move) is for when we have to work the metal, then we normalize again after we finish to get the grains small again

Well not quite alone. Again I'll refer you to the heat treaters guide companion.

 

And from a good knife Smith. Check his procedures for a few commonly used steels by both Blacksmiths and knife Smith's. Also the page before lists his general steps. Which match mine.

 

http://www.cashenblades.com/steel/1080.html

 

Again, stated I do not want to turn this into a debate. You should follow what you believe is best. 

I stand in good company with these two sources, so offer them as a historical alternative to contemporary thoughts. 

Lol, I've never been one to just follow the accepted social thoughts of the day.

 

 

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Oh, Steve Sells

22 hours ago, SLAG said:

Mr. Anvil,

Could you please mention the title of Verhoeven's book?

Thank you.

SLAG.

 

This is the post I meant to quote for the info on Verhoeven. 

Alas, you must have missed it.  ;)

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