Electron beam welding behavior of a 5083-H15 alloy containing Zr and Sc
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RESEARCH PAPER
Electron beam welding behavior of a 5083-H15 alloy containing Zr and Sc Yu-Chih Tzeng 1
&
Ren-Yu Chen 2
Received: 25 April 2020 / Accepted: 25 June 2020 # International Institute of Welding 2020
Abstract This study discusses the effects of the addition of Sc and Zr on the microstructure, and mechanical and corrosion properties of an electron beam welded 5083-H15 alloy. The results show that the addition of Sc and Zr to a 5083 alloy exerted a remarkable effect on grain refinement resulting in an enhancement of the mechanical properties. Moreover, the addition of Sc and Zr prompted precipitation of Al3 (Sc, Zr) precipitate in the heat-affected zone during the electron beam welding, thereby hindering the movement of dislocations and inhibiting recrystallization, effectively improving the tensile strength, joint efficiency, and hardness of the welded joint. Combined additions of Sc and Zr to a 5083 alloy led to a remarkable enhancement in the resistance to intergranular corrosion at the weld joints as determined via nitric acid mass loss tests for a reduction from 9.72 to 3.61 mg/cm2. The main reason for the improvement in corrosion resistance is the addition of Sc and Zr. Recrystallization at the welded joint was inhibited by the formation of the Al3 (Sc, Zr) phase during the electron beam welding which acted to suppress the formation of the β phase along the grain boundaries in the welded zone. Keywords Electron beam welding . Microstructure . Al3 (Sc, Zr) . Mechanical properties . Al-Mg alloy
1 Introduction The 5xxx series Al-Mg alloys, specifically the H116 and H321 temper grade alloys, have been used in marine applications for several decades [1]. The most commonly accepted marine grade Al-Mg alloy being AA5083 [2] due to its high strength, easy weldability, and good formability. Although AA5083 alloys are widely used in the marine industry, some critical problems associated with them remain related to (i) corrosion control and (ii) weldability. These two problems are the biggest issues hindering the application of these alloys in the marine environment. It is well known that the Al–Mg Recommended for publication by Commission IX - Behaviour of Metals Subjected to Welding * Yu-Chih Tzeng [email protected] 1
Department of Power Vehicle and Systems Engineering, Chung-Cheng Institute of Technology, National Defense University, Taoyuan City 33551, Taiwan
2
Department of Marine Mechanical Engineering, R.O.C. Naval Academy, Kaohsiung City 81345, Taiwan
alloys tend to become “sensitized” [3, 4]. This occurs when the intermetallic β phases (Mg2Al3) precipitate at the grain boundaries to form a continuous mesh. The sensitized Al– Mg alloys are susceptible to intergranular attack, including intergranular corrosion (IGC) or stress corrosion cracking (SCC) [5]. It has been found in several studies [6–8] that the addition of minor alloying elements, such as scandium (Sc), zirconium (Zr), or both, can dramatically improve the strength [6] and effectively decrease the susceptibility of an aluminum al
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