Bolting is normally certified on room-temperature tests, but in a hot joint the strength that counts is the strength at service temperature, and the drop can be large. Alloy 718 bolting to ASTM A1014 needs 185 ksi tensile and 150 ksi yield at room temperature, but 145 ksi and 125 ksi at 1200 °F (650 °C).
ASTM A1014 is one specification that requires the test. ASTM A193 (supplementary requirement S1) and F2281 (S8) make high-temperature tests available when the order asks for them. It is a short test: it shows strength at temperature, not how long a bolt will carry its load there, which stress-rupture and creep tests measure.
Read the full elevated-temperature tensile testing page →
model dataSpecimen drawn to ASTM E8 (standard 0.500 in. round, 2 in. gauge length, threaded ends). Temperature tolerance and strain rates from ASTM E21. Alloy 718 minimums at room temperature and at 1200 °F from ASTM A1014. The curve shows the shape of a test only, not a result, and the temperature readings are illustrative; the furnace, thermocouples, extensometer and machine are generic.
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