Friction Welding and AE Characteristics of Magnesium Alloy for Lightweight Ocean Vehicle |
Kong Yu-Sik,Lee Jin-Kyung,Kang Dae-Min |
Bukyong Education Center for Vehicle Safety Component Technology Pukyong National University,Dept. of Mechanical Engineering Dongeui University,Dept. of Mechanical Engineering Pukyong National University |
해양차량 경량화용 마그네슘합금의 마찰용접 및 AE 특성 |
공유식,이진경,강대민 |
부경대학교 BEST센터,동의대학교 기계공학과,부경대학교 기계공학과 |
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© 2011 The Korean Society of Ocean Engineers
Open access / Under a Creative Commons License
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Keywords:
Friction welding, Base metal (BM), Heat affected zone (HAZ), Welding condition, Mg alloy, AE count, Energy |
핵심용어:
마찰용접, 모재, 열영향부, 용접조건, 마그네슘합금, 음향방출 카운터, 에너지 |
Abstract |
In this paper, friction welded joints were constructed to investigate the mechanical properties of welded 15-mm diameter solid bars of Mg alloy (AZ31B). The main friction welding parameters were selected to endure reliable quality welds on the basis of visual examination, tensile tests, impact energy test, Vickers hardness surveys of the bonds in the area and heat affected zone (HAZ), and macrostructure investigations. The study reached the following conclusions. The tensile strength of the friction welded materials (271 MPa) was increased to about 100% of the AZ31B base metal (274 MPa) under the condition of a heating time of 1 s. The metal loss increased lineally with an increase in the heating time. The following optimal friction welding conditions were determined: rotating speed (n) = 2000 rpm, heating pressure (HP) = 35 MPa, upsetting pressure (UP) = 70 MPa, heating time (HT) = 1 s, and upsetting time (UT) = 5 s, for a metal loss (Mo) of 10.2 mm. The hardness distribution of the base metal (BM) showed HV55. All of the BM parts showed levels of hardness that were approximately similar to friction welded materials. The weld interface of the friction welded parts was strongly mixed, which showed a well-combined structure of macro-particles without particle growth or any defects. In addition, an acoustic emission (AE) technique was applied to derive the optimum condition for friction welding the Mg alloy nondestructively. The AE count and energy parameters were useful for evaluating the relationship between the tensile strength and AE parameters based on the friction welding conditions. |
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