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Need some advice regarding forklift fork steel

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Hey all,

Almost five years ago, I acquired a #75 Bradley hammer, and since then I've been using the dies that came with it.  The upper die works fine, but the lower keeps deforming on me.  I suspect it may be mild steel. 

Anyway, I decided recently to make a couple sets of dies out of a forklift tine that I have since I've read that they are usually 4340 or 4140.  So I chopped it up into sections with my bandsaw, but decided to slice off a thin piece and try heat treating it first, before going to any more trouble.

I soaked one sample piece at 1575 F for 30 minutes, then quenched in oil.  After it had cooled to room temperature, I tried to break it in a vise, and couldn't.  Tested it for hardness, and it's 23 RC.

I have another sample soaking at 1475, and I'm going to water quench it.  I expect similar results, though.

So, what do you guys think?  My data sheets for 4340 and 4140 say they should have an as-quenched hardness in the low 50's RC.   

Have there ever been forklift tines made out of mild steel?


Thanks for your help,


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Heat Treaters bible said you did things right...1575 f and oil quench for 4140 so I'd look at aspects of your process---longer soak?  Better quench?  Temp control?

4340 effectively the same except 1550 f and what appears from the graph to be a MUCH longer soak.


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I used to try to guess what a particular batch of steel was, but too many times I discovered I'd mis-guessed only after spending dozens of hours working on a piece.  Now, if I'm going to use a batch of mystery steel for something important, I chop off a small piece and send out it to be tested first.  I've used these guys in the past: http://www.labtesting.com/services/metal-testing/, but a google search for "steel alloy content testing" will bring up lots of options.  Usually, you can get a definitive analysis, that is full alloy content and tool steel type, for under $100.  Might seem like a lot of money, but if your time has any value, it's easy to spend much, much more by being mistaken about what your working with.  (In fact, I have an absolutely beautiful tanto sitting on my workbench, forged, clay quenched and almost finished.  The dozen or so small cracks weren't apparent until I got to the final finishing stages.  Turns out, what I thought was S2, was in fact S5, which, as it happens, doesn't appreciate being quenched in water.)

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Good for you...I live in Yuma AZ, the lettuce capital of the world. So there are lots of fork truck rental/repair shops in town.  Using every bit of my  persuasive  charm, I haven't obtained a singe piece of broken tine.  The standard reply has been "sorry, there is too much liability to "give/sell".   A broken tine is...well ..broken.

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  • 4 years later...

i have fork truck tines on my 60 pound tire hammer for about a year and i use all different tooling as well, dies are holding up really well with about 20 hrs of use on them a week for about a year now and no deformation or cracking. I used them as is figuring id replace them easily enough if they didnt hold up but theres been no issue. i make damascus and forge mostly tool steel under my hammer too. 

All tines are different so try it out, dont expect much and you may be pleasantly surprised


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