Applicability of Simplified Methods to Alloy 617 in Excess of 649°C

The Alloy 617 draft Code case does not permit the use of simplified methods to assess ratcheting when temperatures exceed 649°C. This restriction was placed due to an apparent difficulty in distinguishing between creep and plastic deformation at various strain rates for this material. A numerical evaluation of the B-1 and B-2 Tests for a tube under constant pressure and cyclic thermal gradients (linear and nonlinear) was made. Analysis results indicate that simplified methods currently in Appendix T of ASME-NH are applicable for Alloy 617 in excess of 649°C.Copyright © 2007 by ASME