Effect of welding heat input on hardness of stir zone for friction stir-welded 2024T3 aluminum alloy.pdf

Materials Science Engineering A 559 (2013) 319–324Contents lists available at SciVerse ScienceDirectMaterials Science Engineering A0921-50 http://d n Corr and Tec Tel.: t8 E-mjournal homepage: /locate/mseaEffect of welding heat input and post-welding natural aging on hardness of stir zone for friction stir-welded 2024-T3 aluminum alloy thin-sheetRui-dong Fu a,b,n, Jian-feng Zhang b, Yi-jun Li b, Ju Kang b, Hui-jie Liu c, Fu-cheng Zhang a,b a State Key Laboratory of Metastable Materials Science and Technology, Qinhuangdao 066004, Hebei Prov., PR China b College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004, Hebei Prov., PR China c State Key Laboratory of Welding and Joining, Harbin 150001, Heihongjiang Prov., PR Chinaa r t i c l e i n f o Article history: Received 10 June 2012 Received in revised form 6 August 2012 Accepted 22 August 2012 Available online 30 August 2012 Keywords: Hardness measurement Aluminium alloys Welding Precipitation Grain growth93/$ - see front matter 2012 Elsevier B.V. A /10.1016/j.msea.2012.08.105 esponding author at: State Key Laboratory of hnology, Qinhuangdao 066004, Hebei Prov., P 6 335 8074795; fax: t86 335 8074545. ail address: rdfu@ (R.-d. Fu).a b s t r a c t The hardness of stir zone (SZ) at as-weld state and post-welding natural aging (PWNA) state under different heat input conditions were investigated for friction stir-welded joints of 2024 aluminum alloy thin-sheets. Results show that welding heat input has obvious effect on the hardness of the SZ. Under the high welding heat input condition, the hardness of the SZ is lower than that of the base metal (BM). However, under low welding heat input condition, the hardness of the SZ exhibits strong dependency on the rotational speed of the stirring tool. With increasing the rotational speed of the stirring tool, the hardness of the SZ increases. The average hardness in the SZ of the joint welded at 1500 rpm and 1000 mm/min achieves the BM level. In comp