2022 №04 (03) DOI of Article
2022 №04 (05)

Automatic Welding 2022 #04
Avtomaticheskaya Svarka (Automatic Welding), #4, 2022, pp. 19-25

Fibre laser welding of aluminium alloys OF 7ххх series (Al–Zn–Mg–Cu) by non-through thickness welds

V.M. Korzhyk1, V.Yu. Khaskin1, A.A. Grynyuk2, S.I. Peleshenko3, Yao Yuhui4, S.G. Hryhorenko2, V.O. Shcheretskiy2, O.S. Kushnarova2

1China-Ukraine Institute of Welding, Guangdong Academy of Sciences, Guangdong Provincial Key Laboratory of Advanced Welding Technology, Guangzhou, 510650, China. E-mail: patonjournal@gwi.gd.cn
2E.O. Paton Electric Welding Institute of the NAS of Ukraine. 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: office@paton.kiev.ua
3NTUU «Igor Sikorskiy Kyiv Polytechnic Institute». 37 Peremohi Prosp., 03056, Kyiv. E-mail: imz.paton.kpi@gmail.com
4Shenzhen Hanzhizi Technology Co., Ltd. 6th Floor, Building B, Bantian International Center, 5 Huancheng South Road, Longgang District, Shenzhen, Guangdong, China, E-mail: 514929948@qq.com

The paper deals with the features of laser welding with incomplete (non-through thickness) penetration of high-strength aluminium alloys of 7ххх series. It was found that at joining of 1.5 mm sheets by fibre laser welding to the depth of 0.5…0.7 mm there arises the risk of formation of pores, in particular, in the root zone, streaks of oxide film in the weld lower part, as well as hot cracks. The latter can be eliminated by reducing the heat input below 25 – 30 J/mm. The weld metal is characterized by an equiaxed finely dispersed structure with grain size of 10…15 ~m for 7005 alloy and 15…25 ~m for 7075 alloy. In the fusion zone, the grains are of an elongated shape with 2.5…3.0 coefficient for 7005 alloy and 2…5 for 7075 alloy. In the HAZ the grain length is reduced, the shape coefficient becomes 3…5 and 3.0…3.5 for 7005 and 7075 alloys, respectively. At performance of laser welding with small (~5 J/mm) values of the heat input, microhardness of the welds and HAZ is rather uniform, and close to that of the base metal. For 7075 alloy microhardness drop to 20% was observed in the fusion zone region, that is due to formation of grains of an elongated shape with shape coefficient of 2…5. The found drawbacks can be eliminated through reduction of pulsations of the vapour-gas channel with simultaneous increase of the stability of its existence and introduction of cathode breaking of the oxide film. 11 Ref., 4 Tabl., 8. Fig.
Keywords: aluminium alloys of 7ххх series, laser welding, weld formation, graininess, defects, ways to eliminate

Received: 28.03.2022


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