| Title |
Effects of Peak Temperature of Weld Thermal Cycle on the Microstructure and Mechanical Properties in the IRHAZ of Nuclear RPV Steel Weld |
| Authors |
문종걸(Jong Gul Moon),김주학(Joo Hag Kim),홍준화(Jun Hwa Hong),이창희(Chang Hee Lee) |
| Abstract |
The microstructure and mechanical properties in the intercritically-reheated heat-affected zone (IRHAZ) of an SA 508 Cl.3 Mn-Mo-Ni reactor pressure vessel (RPV) steel have been investigated systematically using the welding thermal cycle simulated specimens. The double thermal cycles with varying peak temperatures(T_(p1), T_(p2)) in the range 700-800℃ were applied to simulate the various IRHAZs using a Gleeble 1500 thermal simulator. The effect of post-weld heat treatment (PWHT) was also studied. The microstructures of the IRHAZs were mainly composed of bainite, martensite and tempered bainite. But the specimens subjected to T_(p1)=T_(p2)=750℃ (before PWHT) and subjected to T_(p1)=T_(p2)=700℃ (after PWHT) showed lowest toughness. The microstructural factors affecting toughness were discussed with reference to the fraction of high carbon martensite for the specimen before PWHT, and to they coarsened carbide and softened matrix for the specimen after PWHT. |