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Forging stainless steel under the power hammer ?


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post-15148-0-56255800-1401762161_thumb.jpost-15148-0-54440100-1401762083_thumb.jI'm finding that the 2" round 316 bar always fracktures and splinters after drawing down under the hammer. I'm keeping it nice and hot but as I work it down into a point I can feel all the delaminations catching my hand as I feel along the taper. Any advice would be awesome, thanks Col.

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Just wondering if anyone can help. I am drawing down 2" 316 bar to a taper and every time it gets ratty. It gets cracks and delaminates and just feels like splinters.I am keeping the thing nice and hot but the more I work it the xxxxx it gets, HELP

post-15148-0-64084000-1401837692_thumb.jpost-15148-0-23924900-1401837785_thumb.j

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http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CE0QFjAD&url=http%3A%2F%2Fwww.speedymetals.com%2Finformation%2FMaterial49.html&ei=AGqOU-_DO9GpyASHgoLQBw&usg=AFQjCNEMxg_CzXr1VEx_jkCmtFWjR1MoPQ&bvm=bv.68235269,d.aWw&cad=rja

 

MACHINEABILITY AND WELDABILITY

Machinability is rated at 36% of B1112. Average cutting speed 60 ft/min. Easily welded by all commercial processes except forge or hammer welding. Annealing is recommended after forging to maintain maximum corrosion resistance. 316/316L can be forged between 2100°-2300° F. Do not forge below 1700° F.

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Hey Col

Put up the right pictures old son, ie the ones of the stainless, do we need to go powerhammer forging 102 my son, are you forging it square then oct etc, you are controlling the metal are you, ie not flattening it out one way then having to near on flatten it the other way, but taking it down in a nice even tapered square, then taking off the corners, then rough round.

 

Phil

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One thing to keep in mind when working exotic materials is how much deformation you do per blow. Some of them require a gentler approach than you use with carbon steels. Also, in some case you need to forge square, octagon square, not just square all the way down. The only way to know is to experiment, but we utilize these techniques on large forgings from time to time and they can work.

 

Also, with some stainless grades you actually need to forge COOLER that you would for plain carbon materials.

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Sorry folks, I could'nt find the post after I posted it ? I thought it was a non ferrous metal and so posted it there and then could'nt find it, a little knowledge is a dangerous thing in my case, therefore posted the question twice.

Okay, now I have it, Phil, yes I'm drawing it down in the square then rounding it off, and as soon as the colour is gone out of it I'm back to the forge (oil forge) . It only breaks down as I reach the last third of the taper and even then I only notice it when I'm cleaning it up ( so then it's out with the welder/grinder )

I'm reading something MOONY sent me about working temps and "soaking" what ever that means, and so will try again when I've come up to speed a bit. P.S. I can't show the actual cracks as I've fixed them up, but the photos were to show what I've been trying to achieve.

 

Can anyone tell me what this is about ? You have been placed on moderator queue. This means that all content you submit will need to be approved by a moderator before it will be shown

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"and as soon as the colour is gone out of it I'm back to the forge"

 

You need to stop way before that. Colour is a bit hard to communicate in text, but "orange" is at the low end of working temperature for this alloy. "Red" is too cold. By the time you can't see any color (i.e. "black"), it's 300-400°C too cold.

 

"soaking"

 

Thick pieces of metal can get very hot on the outside while still being much cooler on the inside. So, you will have to heat large pieces longer than you might expect so the heat has time to penetrate to the middle.

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"316/316L can be forged between 2100°-2300° F. Do not forge below 1700° F."   remember this post?

 

Colour starts around 1000 deg F so if you are following it down that far you are WAY WAY TOO COLD!!!!!!!!!!!!!!! This is NOT "Nice and Hot"

 

Don't worry about moderation most of us have run into it at some point, just remember to help keep this a "G" rating  (I was once warned for a phrase that I had used in Church the previous day...)

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If it makes you feel any better knowing,  I have been warned about language a few times myself, even tho I thought it was fine also. No worries, welcome to the forum.  Forge on and welcome to the brotherhood (we have Children and a few sisters here also)

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Thanks very much EricJergensen for your explanation, I was having trouble with the soaking thing. ThomasPowers, yes I can see now that working it till the colour is almost gone is to cold, I will not go below bright orange (very short working time, got it ).E.F. Thumann, yes you are right I did use the "s" word in my second post, but I was being moderated before that, and you can see the word was let through anyway, but yes I take the point that "g" rating is key.(still dont realy know why I'm on it though). And thanks heaps to you all for the feed back, it's very much appreciated and will post here after the next attempt.

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Try working some of it in small sections with hand hammer. You'll see it is not just a short working time but a short working temperature. I've done some cupping tools lately using some stainless, as well as a couple other tools. Each one worked different. When doing the cupping tools the SS worked real nice and smooth, then there is a sudden point where it is still (my eye color perception) orange and it stops moving. Practice watching for that temp by hand, then you will know it when you do it under the power hammer. Hope that made sense and helped.

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Thanks Rashelle, all advise from past hands on experience is good advise, and I'm realising that what I have chosen to work with here is tricky in anybodys book, which makes me feel better about my blind attempts so far.

 

Woohoo, it seems I'm able to just post stuff straight out now, thanks folks, promise I won,t say bad words :rolleyes:

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You are welcome. By doing some by hand you'll learn to recognize the low end of the working colors faster. To me at least there is a moment where if you go past it the material stops moving. When it stops you know you wanted to stop before then, heehee. That should train you in the low end of the working colors for that particular alloy.

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Well said Rashelle. It's like cold working copper alloys, do it in the sweet spot and it moves like butter. Try moving it when it starts work hardening and you're walking into it's failure mode.

 

Feel and color are good cues but another is sound, with a little experience you can hear it reach it's limit.

 

Metal talks to you if you speak the language and it speaks many tongues, sight, feel, song. Gotta pay attention to them all unless you LIKE surprises. Surprises can be good but. . . <wink>

 

Frosty The Lucky.

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Okay, I'm into the next set of torches and not letting the metal get below orange (starting out yellow) and staying nice and square as I go down the taper forgemaster, and I've got it into the round, and NO CRACKS, woohoo. Thanks everyone. I think Frosty had it right about listening to the metal.
You would'nt believe it, when I polished them , just one out of four had the same hairline cracks/delaminations.


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Col why does it look like it has been run over by a steam loco?  Are you also putting a textured finish on the steel as well, or is it supposed to be smooth?

I'm leaving the marks on because the look I'm going for is polished but rough, I have thought about swages and a nice perfect finish but it would just look like someone turned it on a lathe, hand made/distressed look is better I reckon.

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While it looks cool, those scale cold laps can/will come loose and can cut someone. A quick stroke or two with a wire brush when it comes out of the fire to knock the scale off before it goes on the anvil usually takes care of driving scale into the work piece.

 

Leaving an as forged or hammer texture, heck any texture, should be a deliberate process rather than just what happens.

 

Frosty The Lucky.

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