TOUGHNESS INVESTIGATION ON SIMULATED WELD HAZS OF SQV-2A PRESSURE-VESSEL STEEL

In order to get detailed information about weld HAZs toughness of SQV- 2A steel and determine the optimum welding and heat treatment paramete rs, the toughness of simulated CGHAZs (coarse grained heat affected zo ne) and CGHAZs (intercritically reheated CGHAZ) were systematically in vestigated. The influence of tempering thermal cycles on weld ICCGHAZs toughness was clarified. The effect of post weld heat treatments (PWH T) on weld CGHAZs toughness was also determined. The results showed th at high toughness (absorbed energy > 200 J) of weld HAZs could be achi eved by selecting the optimum welding and PWHT parameters (cooling tim e Delta t(8/5): 6-40 s, PWHT: 893 K, 3.6-7.2 ks). Tempering thermal cy cles with peak temperature of above 573 K could remarkably improve the toughness of deteriorated ICCGHAZs and reduce the hardness, when cool ing time Delta t(8/5(2)), of the reheating thermal cycle was 6 s, whic h implies that welding of SQV-2A without PWHT is possible, provided th at low heat input welding is adopted and welding procedure is correctl y arranged. Metallography and fractography revealed that M-A constitue nts in weld HAZs played an important role in controlling weld HAZ toug hness. (C) 1998 Elsevier Science S.A. All rights reserved.