The Controlled Heating-Rate Tensile (CHRT) test is an excellent measure of the resistance of gamma-prime forming superalloys to strain-age cracking. Samples of thickness 0.063” (1.6 mm), originally in the solution annealed condition, are heated to the test temperature at a rate of 25-30°F (14-17°C) per minute, this being representative of a typical post-weld heat treatment. In this case, tests were performed at 1450°F (788°C). The susceptibility to strain-age cracking is related to the minimum tensile elongation observed within that temperature range (the higher the minimum elongation, the greater is the resistance to strain-age cracking).
||CHRT Elongation (%)*
*Average of three tests.
**Average of two heats
Controlled Heating Rate Test - 100°F/sec to 1100°F - 30°F/minute to 1450°F - Hold 1450°F and pull to failure at 0.0625 inches/minute
Metzler, D.A. 2008. A Gleeble®-based Method for Ranking the Strain-Age Cracking Susceptibility of Ni-Based Superalloys, Welding Journal 87(10): 249-s to 256-s.