17-4 PH
17-4 PH
(OP)
We are machining a part out 17-4PH. The bar stock is annealed 5.25"dia x 12" long. We will be machining a section to approx 4.5" outside diameter X 5" long with an internal 3.75-12 thread (4.5" deep). The application requires we restrict rotation so the 4" diameter internally threaded section will be split with (4) (0.125"x4" deep slots 0, 90, 180, 270 degree locations) allowing us to clamp the part in place. After machining we will precipitation harden it to approx 35RC. My question is should I expect any movement when I machine the slots? Is there a stress relieving operation that we should perform after rough maching? What temp and time? Where can I find this information?
Thanks,
Thanks,





RE: 17-4 PH
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We have literally thousands of precision parts machined from 17/4 and we normally machine the parts after precipitation hardening. We use mostly in the H1000 or H1150 condition. 17/4 contacts during the precipitation hardening process. We have never used any form of stress relief and we work in tenths. I think you metal is in Condition A.
RE: 17-4 PH
It has one more advantage that the part will be clean and ready for passivation while in the way you suggested it will have a heat tint after the heat treatment which will require the removal of the heat ting before passivation. This heat tint removal process can change the dimensions further by 0.004".
RE: 17-4 PH
machines nicely at/upto 45 HRc
it is preferable to machine in the harden condition.
35 HRc is perfect for machining.:/
then stress relieve at a lower temperature if
its needed after machining. but I know some of you will say it alters physical properties.:(