Effect of heat treatment on microstructure and properties of 2219 aluminum alloy plate friction stir welding joint
YU Xiaolong
DING Huili
LI Mengzhuo
WANG Zhixin
Abstract：This study investigates the effects of solution quenching and aging heat treatment on the microstructure and mechanical properties of 8 mm-thick 2219 aluminum alloy joints fabricated by fric-tion stir welding using the metallographic microscopy and microhardness testing.By comparing and analyzing the grain size distribution and hardness changes of the weld seam before and after heat treat-ment,the relationship between heat treatment process parameters and microstructure properties is re-vealed,and the influence mechanism of mechanical properties is elucidated.Results showed that grain coarsening occurred in heat-affected zone,thermo-mechanically affected zone,and weld nugget zone after solution-aging treatment,with finer and more uniformly distributed precipitated particles in weld nugget zone compared to base metal.The hardness of heat-treated joints increased to 116.6 HV,re-presenting a 67％improvement over pre-treated specimens.When the aging time extended to 20 hours,joint hardness approached parity with the base metal.Analysis revealed that numerous fine dispersed particles precipitated in weld microstructure after heat treatment demonstrated an effective dispersion strengthening effect,significantly enhancing joint mechanical properties.This research provides theoretical foundation and scientific basis for the application of aluminum alloy friction stir welded plates in structural lightweight and integrated forming technologies.
Keywords：aluminum alloyfriction stir weldingheat treatmentweldsmicrostructurehardness
Publication Date：2025-06-25
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 42-47 )