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WKTaylor
Active member
- Sep 24, 2001
- 4,067
Guys...
I tried to recommend sheet PH SSTL materials and was stopped in mid-stream by M&P guys. The following cryptic message on their website was the stumbling block...
"CAUTION: Starting in about 2004 the only vendor of PH SSTL sheet including 15-5PH, PH15-7Mo, 17-4PH and 17-7PH started listing exceptions on the material certifications delivered. These exceptions mean that they are delivering material which does not meet the specifications for the reasons stated on the certification. There have been exceptions for various specification requirements but the most common is air melting where the specification requires vacuum melting. This commonly results in increased incidence of inclusions in the material compared with vacuum melt practice. This does not affect the static tensile properties but can have a negative impact on fatigue. That impact has not been characterized as of this writing. Avoid use of these sheet steels if you can."
It seems almost incomprehensible that CRES sheet manufacturers would not be able to acquire the high quality VAR billet that would result in high-quality/high-reliability Aero-grade sheet. The M&P guys also went on to state that the single-source vendor for these Aero-grade sheets was not willing step-up to meet the specs [not cost effective?].
NOTE. When I pressed them for "how bad was the problem" the M&P guys said that inner-laminar imperfections in thin sheet metal were not only possible, but probable (somewhere in each large sheet)... and that the only way to reliably detect inner-laminar defects was by 100% ultrasonic NDI aand MPI of every piece of material: hence the posted CAUTION.
Anyone else aware of this issue? Suggestions/Comments?
Regards, Wil Taylor
Trust - But Verify!
We believe to be true what we prefer to be true.
For those who believe, no proof is required; for those who cannot believe, no proof is possible.
I tried to recommend sheet PH SSTL materials and was stopped in mid-stream by M&P guys. The following cryptic message on their website was the stumbling block...
"CAUTION: Starting in about 2004 the only vendor of PH SSTL sheet including 15-5PH, PH15-7Mo, 17-4PH and 17-7PH started listing exceptions on the material certifications delivered. These exceptions mean that they are delivering material which does not meet the specifications for the reasons stated on the certification. There have been exceptions for various specification requirements but the most common is air melting where the specification requires vacuum melting. This commonly results in increased incidence of inclusions in the material compared with vacuum melt practice. This does not affect the static tensile properties but can have a negative impact on fatigue. That impact has not been characterized as of this writing. Avoid use of these sheet steels if you can."
It seems almost incomprehensible that CRES sheet manufacturers would not be able to acquire the high quality VAR billet that would result in high-quality/high-reliability Aero-grade sheet. The M&P guys also went on to state that the single-source vendor for these Aero-grade sheets was not willing step-up to meet the specs [not cost effective?].
NOTE. When I pressed them for "how bad was the problem" the M&P guys said that inner-laminar imperfections in thin sheet metal were not only possible, but probable (somewhere in each large sheet)... and that the only way to reliably detect inner-laminar defects was by 100% ultrasonic NDI aand MPI of every piece of material: hence the posted CAUTION.
Anyone else aware of this issue? Suggestions/Comments?
Regards, Wil Taylor
Trust - But Verify!
We believe to be true what we prefer to be true.
For those who believe, no proof is required; for those who cannot believe, no proof is possible.
