Optimization of Friction Welded Joint Conditions in Alloy718 and the Nondestructive Evaluation

J. Ocean Eng. Technol. 2008;22(1):53-57.

Kwon Sang-Woo,Kong Yu-Sik,Kim Seon-Jin

Graduate School of Mechanical Engineering Pukyong National University,School of Mechanical Engineering Pukyong National University,School of Mechanical Engineering Pukyong National University

Alloy718 마찰접합조건의 최적화와 비파괴 평가

권상우,공유식,김선진

부경대학교 기계공학부 대학원,부경대학교 기계공학부,부경대학교 기계공학부

Keywords: Friction welding(FRW), Heat affected zone(HAZ), Weld interface(WI), Acoustic emission(AE), Ultrasonic attenuation coefficient

핵심용어: 마찰용접, 열영향부, 용접계면, 음향방출, 초음파 감쇠계수

Abstract

Friction welding was performed to investigate mechanical properties for Ni-base superalloy with 15 mm diameter solid bar. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, impact energy test, Vickers hardness surveys of the bond of area and heat affected zone. And then, the nondestructive technique to evaluate the weld quality was carried out by acoustic emission(AE) and ultrasonic attenuation coefficient. The tensile strength of the friction welded joint was shown up to 90 % of the Alloy718 base metal under the condition of the heating time over 5 sec. The optimal welding conditions were n=2,000 rpm, $P_1=200$ MPa, $P_2=200$ MPa, $t_1=8$ sec and $t_2=5$ sec when the total upset length was 4.4 mm.