316 Class 2 Bolts
316 Class 2 Bolts
(OP)
It is my understanding that class 2 316 and 304 bolts under the A193 and A320 specs are not to be hot forged because the material is strain hardened. We received some bolts that were hot forged from class 2 material and were full size axially tensile tested. The test show the bolts exceeding the required mechanicals (tensile and yield) for both specs. Is there something else I'm missing or are the bolts acceptable under those specs as long as they have the required chemicals and mechanicals even though it is suggested they not be hot forged? Any help is appreciated.





RE: 316 Class 2 Bolts
These may have been warm worked from previously strain hardened bar.
If they weren't careful with the temps they could be seriously sensitized.
If they were truly hot formed they would be dead soft.
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P.E. Metallurgy, Plymouth Tube
RE: 316 Class 2 Bolts
RE: 316 Class 2 Bolts
RE: 316 Class 2 Bolts
Sensitization is a condition detrimental to corrosion resistance of the parts, and the solution annealing process is meant to avoid sensitization.
ASTM A193 requires specific head markings based on the grade and class. For example, Grade 8 Class 1 is marked B8. Grade 8 Class 2 is marked B8SH.
RE: 316 Class 2 Bolts
RE: 316 Class 2 Bolts
RE: 316 Class 2 Bolts
RE: 316 Class 2 Bolts
RE: 316 Class 2 Bolts
RE: 316 Class 2 Bolts
That is not a hot formed fastener.
If they are hot forged it does not matter what you started with, it will be annealed when you are done.
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P.E. Metallurgy, Plymouth Tube