Stress Relief Cracking in Heat-Affected Zone (Report 1)
Heat-affected zone cracking due to stress relief heat treatment has been investigated on a wide variety of ferritic steels by simple welding tests and a bend restraint SR cracking test.The results indicate that intercrystalline cracking may occur during the heat treatment ; local stress raisers are necessary to initiate this cracking ; this cracking may not occur in deposited metal and parent metal inaffected ; and susceptibility to cracking depends markedly on chemical composition.Suggested remedies for the cracking problems are : the use of (1) buttering technique prior to welding, (2) grinding off the excess weld metal to remove the notch of the weldment before stress relieving, and/or (3) preventive bead technique before stress relieving.
We study the relaxational dynamics of the one-spin facilitated Ising model introduced by Fredrickson and Andersen. We show the existence of a critical time which separates an initial regime in which the relaxation is exponentially fast and aging is absent from a regime in which relaxation becomes slow and aging effects are present. The presence of this fast exponential process and its associated critical time is in agreement with some recent experimental results on fragile glasses. @S0163-1829~96!04426-8#