Impact testing of materials for use at very high strain rates is often conducted at temperatures well below the projected service temperature, because depressed temperature can sort of "pinch hit" for loading rates too high to be achievable in the laboratory.
Impact testing of steels for oil well perforating gun tubes is often conducted at very low temperatures, because most labs do not have licenses for using explosives, nor are they willing to expose themselves to the associated risks.
Too lazy to look it up right now, but I think -100F is specified in at least one ASTM spec for Charpy testing of steels meant for explosive applications - just because it is a round number, a low number, and easily achieved in dry-ice/acetone.
As far as the individual deliberately falsifying the MTRs, that is beyond unforgivable. If one believes the required testing regimen is inappropriate one should state that; don't claim to have conducted the tests as specified and report bogus results, that's lying.
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Andrew Werner
Chief Metallurgist - Retired
Retired
East Bernard TX
(832) 563-3489
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Original Message:
Sent: 11-11-2021 09:28
From: Sean Piper
Subject: NYTimes 11/09/2021 article on Falsified met testing
While obviously I do not condone falsifying test results, I admit that I too have wondered why the material required Charpy testing at -100F when the service environment is never going to get colder than 0F (freezing point of saturated saltwater) and will probably be closer to 30-40F most of the time. Since toughness correlates nonlinearly with temperature, wouldn't it be more sensible to test at the lowest anticipated service temperature and then bake in your safety factor by increasing the absorbed energy requirement at that temperature? How was a 100F safety factor justified in the writing of that spec?
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Sean Piper
Product / Process Metallurgist
Ellwood Texas Forge Houston
Houston TX
(713) 434-5138
Original Message:
Sent: 11-10-2021 12:20
From: James Quinn
Subject: NYTimes 11/09/2021 article on Falsified met testing
Would anyone like to comment on the NYTimes article:
A PDF copy is attached.
"Metallurgist Admits She Falsified Test Results for Steel Used in Navy Submarines
For more than 30 years, ABCDE LMNOPQ altered test results for more than 240 steel
productions while working for a foundry that provides metal for U.S. Navy submarines....."
regards,
- Jim Q
Long Island Chapter