| Title |
Effect of Heat Input on the HAZ Toughness of High Strength Steel ( part 2 ) ( Impact test for thermally simulated heat affected zone ) |
| Authors |
윤종근(J . G . Youn); 김희진(H . J . Kim) |
| Abstract |
The purpose of this study is to clarify the critical factor controlling the HAZ toughness of high strength steel. The HAZ toughness has been known to be directly associated with the characteristics of local brittle zone (LBZ) having lowest toughness within the coarse grained HAZ. The microstructural sources for LBZ, identified in this study as the intercritically reheated coarse grained HAZ, were confirmed to be the presence of MA constituent formed in the coarse grained microstructure. The amount of the M-A constituent, which controls the HAZ toughness. is strong1y dependent on both the conditions of weld thermal cycle and the chemical composition of base metal. The amount of the MA constituent formed in the TMCP steel decreases significantly with increasing the cooling time, while that in the normalized steel does not. This fact can explain the effect of welding heat input on the HAZ toughness of TMCP steel and normalized steel reported in Part l. |