Fabrication of large-bulk ultrafine grained 6061 aluminum alloy by rolling and low-heat-input friction stir welding

C.Y.Liu^1,2，B.Qu²，P.Xue¹，Z.Y.Ma¹，K.Luo³，M.Z.Ma⁴，R.P.Liu⁴

1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences2. Key Laboratory of New Processing Technology for Nonferrous Metal & Materials, Ministry of Education, Guilin University of Technology3. Guangxi Key Laboratory of Universities for Clean Metallurgy and Comprehensive Utilization of Nonferrous Metal Resources, Guilin University of Technology4. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University

摘 要：In this study, the ultrafine grained（UFG） 6061 Al alloys fabricated by cold rolling were friction stir welded（FSW） with different rotation rates under both air cooling and rapid cooling in water. Low-heat-input parameters of 400 rpm rotation rate in water（400-Water） could effectively inhibit the coarsening of recrystallized grains, reduce the precipitation rate, and retain more dislocations of the UFG 6061 Al parent metal. 400-Water joint showed high lowest-hardness value, narrow low-hardness zone, and high tensile strength, attributing to the effect of dislocation, grain boundary, solid-solution, and precipitation hardening. This work provides an effective strategy to fabricate large-sized bulk UFG Al alloy by cold rolling with large deformation and low-heat-input FSW.

关键词：