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Generally, welding on quenched and tempered steel conducted using preheat and post-heat to avoid failure of the weldment. Some operators do not preheat before welding and post-heat after welding is complete. In this study, Q&T Steels welded using double-pass without preheating and post-weld heat treatment. Some operators do not use preheat and post-weld heat treatment, even welding is finished cooled by using water medium. Microstructural and mechanical evaluations of quenched and tempered steel welded joints investigated to reveal the effect of water quenching on the heat-affected zone in this study. Austenitization used for quenching are 750oC, 800oC 850oC and 900oC were selected. The specimens observed by spectrometer for observation in chemical element content; optical microscopy for observation in microstructure; microhardness Vickers tester for hardness observation in microstructure; impact testing machine for observation in impact energy. The aim of this study to obtain the characteristics of Quenched and Tempered Steel weld joints cooled by freshwater. The results indicate the hardness of the heat-affected zone increases with increasing austenitization temperature, but the hardness of the weld metal decreases.