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I need to make .125 x 4130 straps for a spar connection. I am looking for information on the deformation of 4130 after being heat treated to 125000psi. If the part were drilled before treating, would the holes match after heat treating? Should the part be drilled after heat treating?
Usually for a bolted connection the tolerances aren't tight enough you have to worry about it. In a former job we had to machine before heat treat (the material was too hard to machine after heat treat) and we had to allow for the warpage due to heat treating, but we were talking tolerance in the range of a couple microns.
Make one & try it out, you will probably be OK.
What about surface scaling inside the holes? This could require post heat treat reaming of the holes, depending on the fit tolerance.
It as been a long time since I did heat treating of stamping dies but I don't remember the 4000 series of steels (shock steels)as being too bad about changing dimensionally. To prevent scaling you wrap the parts in a heat treating foil and I would put some paper in the pouch with the parts. The paper would ignite before the critical temperature was reached, burning away any oxygen in the pouch and that would almost always eliminate any scaling. Dowel fit holes were finished by either Jig Grinding or a Sunnen Hone. Bolt holes were not an issue.
Can 4130 steel be heat treated? I would think it would have to be 4140 or even 4150 before the alloy would seriously respond to heat treatment.
Depends on your definition I suppose. We use 4130 in homebuilding because of it's forgiving nature to hamfisted attempts at welding or drawing or normalizing or whatever someone is claiming to try to do to it with a torch. Can the state of 4130 be altered from the "N" condition we purchase it in? Sure. Do we need to? Most likely not. I'm sure there may be some exceptions.
By definition you can heat treat (alter the state of) 1018 through carbonizing but that is a little different as is nitriding.
It can be heat treated to a certain extent, given the right equipment. I would have to dig out some old Ryerson engineering data to give exact numbers (which I don't have time for on a Monday morning) but 4130 used to be available with strengths quite a bit higher than what is available these days.
(As far as that goes, you used to be able to get 1018 that was way stronger than what is sold now)
I have no idea why but the phrase "hamfisted attempts" made me laugh.Quote:
We use 4130 in homebuilding because of it's forgiving nature to hamfisted attempts at welding or drawing or normalizing or whatever someone is claiming to try to do to it with a torch.
Is there a particular reason for that change?Quote:
but 4130 used to be available with strengths quite a bit higher than what is available these days.
(As far as that goes, you used to be able to get 1018 that was way stronger than what is sold now)
None that I have been able to get a good answer for. Some speculation is that at the time both 4130 & the higher strength 1018 were still being used a lot in the aircraft & defense industries & was being made here in the US by all the major manufacturers. From what I understand all the raw (unformed) 4130 that is drawn into the structural shapes we use here in the US comes from one foundry in Germany & there is no other western source.Quote:
Originally Posted by steveinindy
The thing you have to watch when doing structural design is that some of the well respected textbooks that have been in print for ages & are still used in some of the major engineering schools still have the old yield strength values in the tables in the appendix. Now you need to use the current data (usually very limited) from the supplier you are getting the material from.
(The Ryerson engineering data book used to be an industry standard in design departments, but they quit publishing it years ago for legal reasons. I still use it for some things.)