We have examined the characteristics of welded joint part in order to improve the toughness of HAZ. The probe samples used in this study are the steel plates produced by EAF-Plate mill process bearing Titanium for building. The remarkable improvement of toughness in HAZ is confirmed in the case of ultra large heat input weld condition. It is proved that sufficient HAZ characteristics can be attained by adjust the prompt analysis condition even in large heat input weld condition with 60-90kJ/mm.
