Stringers in 722M24 En40B Nitriding Steel
Stringers in 722M24 En40B Nitriding Steel
(OP)
Hello all,
I'm a newbie to the forum and am in need of some help.
We have a customers crankshaft which we've tested on the Mag bench using the W/C method and we've been finding 'stringers'. Some defects are surface breaking whilst others are not. Some are grouped together but all follow the length of the shaft. How detrimental to the component are these subsurface defects? I've read various articles which would lead me to the conclusion that any of these defects are rejectable even though the customer would like to have a limit on defect size?
Any help would be appreciated.
I'm a newbie to the forum and am in need of some help.
We have a customers crankshaft which we've tested on the Mag bench using the W/C method and we've been finding 'stringers'. Some defects are surface breaking whilst others are not. Some are grouped together but all follow the length of the shaft. How detrimental to the component are these subsurface defects? I've read various articles which would lead me to the conclusion that any of these defects are rejectable even though the customer would like to have a limit on defect size?
Any help would be appreciated.





RE: Stringers in 722M24 En40B Nitriding Steel
RE: Stringers in 722M24 En40B Nitriding Steel
Thanks.
RE: Stringers in 722M24 En40B Nitriding Steel
Most of the acceptance criteria I've seen for such stringer imperfections usually address both a size (length) limit and a density (number found within a specified area) limit. For example, a maximum length of 0.500 inch for any single indication and no more than 3 indications over 0.063 inch in any 1.0 square inch area.
The actual values for the limits have to come from experience and/or trial and error. In the absence of experience, initial limits could be based on the consequence of failure combined with limits that would reject the worst cases while accepting minor groupings, and adjusting depending on performance.
rp
RE: Stringers in 722M24 En40B Nitriding Steel