Microstructure and properties of 2219 aluminum alloy fabricated via additive friction stir deposition

Abstract

The additive friction stir deposition（AFSD）experiment of 2219 aluminum alloy was conducted under the process parameters of the spindle rotational speed of 250-350 r/min and transverse speed of 50-150 mm/min，the effects of varying process parameters and multilayer thermal cycling on the macroscopic forming of deposited materials，microstructures and mechanical properties were investigated. The results show that well-formed single-pass 16-layer additive specimens can be successfully obtained under the process parameters of the spindle rotational speed of 250 r/min and the traverse speed of 100 mm/min. The grain size in the additive zone undergoes significant refinement，ranging from 4 to 6 μm，and the fine equiaxial crystal organization replaces the coarse irregular grain organization characteristic of the feed rod. The additive specimen undergoes intense dynamic recrystallization，with overall recrystallized grains above 80%，and the bottom of the specimen（the 1st Layer）is subjected to multiple thermal cycles，with recrystallized grains reaching 91.8%. The texture of the additive zone basically consists of four recrystallized textures(Cube，Copper，P and RtB)，as well as S，Brass and T textures. Significant softening of the hardness and tensile strength of the additive specimens occurs. The maximum hardness of the 16th layer is 80HV，which is about 55.6% of the base material of the feed rod，the hardness of the 1st-8th layers is uniformly 60HV. The average tensile strength of Layer 9-16 and 1-8 in the LD（longitudinal direction）direction of the additive zone is 243.0 MPa and 219.3 MPa respectively，which is about 60.0% and 52.9% of the base material，the average elongation is 19.4% and 24.5%，which is about 181.1% and 229.0% of the base material respectively. The fracture modes in the LD direction of the additive specimens are all ductile fracture.

Keywords

• additive friction stir deposition(afsd)
• 2219-t87 aluminum alloy
• microstructures
• mechanical properties