CPM M-4 arrived bent!

Troop

Troop

Joined
Oct 26, 2006
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2,898
Hey guys, I wanted to see what the hype was all about with this new-fangled CPM M-4, so I ordered some HRA from Crucible. It just arrived...in bent condition! The piece is 5/16 x 1.5 x 74", and is all kinds of bent. I straightened it over my knee, as best as I could. I wanted to stock remove this stuff, so I wouldn't hurt it by forging, but now.......?
You figure for the amount of money I dropped on this thing, it would at least be straight! I know it's "HRA", but still.
Any idea on how to straighten it?
Is it OK to forge this stuff? I don't want to hurt the steel by forging it.
"Cold forge" it, by beating it straight on my anvil?
Any suggestions?
- Thanks
 
I wouldn't suggest beating it on your anvil. I bridge the high spots and press the kinks out. A serious kink is a problem and should be returned, but gradual bends aren't a big deal and don't reappear after HT.

M4 is a HSS and it comes ready to austenitize. You do not want to subject HSS to high temps more than once because it is a complex procedure to "reset" it. You get one shot at it or you will suffer serious grain growth the second time.

It is acceptable to do a soak at 1200 to stress relieve, which might be a good idea if there were bad bends.

Next time, request saw cut rather than sheared.
 
Mine arrived perfect, but it was 36" not 74". I actually used mine to bend stainless steel because it was so straight. Maybe you could send it back?
 
Nathan the Machinist said:
I wouldn't suggest beating it on your anvil. I bridge the high spots and press the kinks out. A serious kink is a problem and should be returned, but gradual bends aren't a big deal and don't reappear after HT.

M4 is a HSS and it comes ready to austenitize. You do not want to subject HSS to high temps more than once because it is a complex procedure to "reset" it. You get one shot at it or you will suffer serious grain growth the second time.

It is acceptable to do a soak at 1200 to stress relieve, which might be a good idea if there were bad bends.

Next time, request saw cut rather than sheared.
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Thanks, Nathan. No kinks, but "gradual" bends. Thanks for the "no-forging" warning; I figured something like that for that type of steel. I guess I'll just press it straight like you recommended.
I'm pretty sure that's the last time I'll buy the Hot-Rolled Annealed CPM M-4.:thumbdn::grumpy:
 
Troop said:
Did you get the HRA stuff?
Click to expand...

Yeah mine was .156" HRA. Very good quality steel.

You can try as Nathan recommends. I've rehardened CPM M4 before, so here's an alternative: Cut out your piece and austenize it, quench it between quench plates to straighten your warped steel. Then anneal the steel by heating to 1600F, hold 2 hours, slow cool 25F per hour to 1000F. Air cool to room temperature. Now it's ready to be heat treated again.
 
How was it chipped? In a hard/soft tube? Wrapped in tape? most likely it was bent during shipping?
 
Was it sheared? If it came from Admiral and it was sheared, it's very possible that the shears were not set correctly. It would not be the first bar of steel to arrive twisted.
 
Stress relieve after straightening so that it doesn't warp after HT.
 
AcridSaint said:
Was it sheared? If it came from Admiral and it was sheared, it's very possible that the shears were not set correctly. It would not be the first bar of steel to arrive twisted.
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It came directly from Crucible; I expected more coming right from Crucible.
 
Some times for work we have to order material thats long but has to be made sure that when we get it its straight. if we tell the suppler this thy most of the time ship it to us taped to a 2x4 or some other straight ridged material. we do a lot with small drill rod and we where having this problem of getting them bent. and this stock was for real long reamers we make where the shank is like 3-4 feet long. so when shipping 1/8" drill rod that long thy tape a bunch to a 2x4 and we have not had a problem since. that is a bummer that its bent though. like was said i would try using a vice and 3 high points. 2 on one jaw and one on the other and slowly straighten it like you would a blade.
 
JT. Good tip for the future. Judging by the condition of the shipping tube, it looks as though Crucible shipped it to me bent.
What were those guys thinking?
"Hey, we're going under, so screw it?" Who would want to buy a bent piece of steel? I mean, I paid hundreds of dollars for that bent piece of steel.
Jeez, for that money, I could've had another batch of Don Hanson's W2 or 52100 forged flat.
Just goes to show you; "the grass is always greener".
At least with "standard" tool steels, I can forge them straight if I need to.
 
Troop said:
JT. Good tip for the future. Judging by the condition of the shipping tube, it looks as though Crucible shipped it to me bent.
What were those guys thinking?
"Hey, we're going under, so screw it?" Who would want to buy a bent piece of steel? I mean, I paid hundreds of dollars for that bent piece of steel.
Jeez, for that money, I could've had another batch of Don Hanson's W2 or 52100 forged flat.
Just goes to show you; "the grass is always greener".
At least with "standard" tool steels, I can forge them straight if I need to.
Click to expand...

I would give them a call if its anything more then just a slight overall bend. i would consider being bent as bad as you have described to be a manufacture defect.
 
Mitch, sorry to hear but it happens with all steel suppliers.
I can send ya some 2.5" round bars that are straight, real straight. ;)

How long a knives you goin to make, buddy?:eek:
 
Don Hanson III said:
Mitch, sorry to hear but it happens with all steel suppliers.
I can send ya some 2.5" round bars that are straight, real straight. ;)

How long a knives you goin to make, buddy?:eek:
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Don, I should have just gotten more steel from you instead. You can't even forge this stuff straight, for Chrise' sake.:grumpy:
 
I asked how long because if you were to cut 10", 12", or 18" off the bar, these short
length will likely be straight enough to get started?
 
Don Hanson III said:
I asked how long because if you were to cut 10", 12", or 18" off the bar, these short
length will likely be straight enough to get started?
Click to expand...

Oh. I didn't know what you meant, Don. What I'll probably wind up doing is cutting 12" pieces, and bending them straight. Good thing I got 5/16, so I have a lot of room to grind 'em straight.
- Thanks
 
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