搅拌摩擦沉积增材2219铝合金组织及性能

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

在主轴转速250~350 r/min、横向移动速度50~150 mm/min工艺参数下进行2219-T87铝合金搅拌摩擦沉积增材(additive friction stir deposition,AFSD)实验,探究工艺参数与多层热循环对沉积层宏观成形、微观组织和力学性能的影响。结果表明:在主轴转速250 r/min,移动速度100 mm/min工艺参数下可获得成形良好的单道16层增材试样。增材区晶粒尺寸发生显著细化,在4~6μm之间,细小等轴晶组织取代沉积棒料粗大的无规则晶粒组织。增材试样发生剧烈的动态再结晶,整体再结晶晶粒在80%以上,试样底部(第1层)受到多次热循环影响,再结晶晶粒达到91.8%。增材区域织构基本由Cube、Copper、P和RtB四种再结晶织构以及S、T和Brass织构构成。增材试样的硬度和抗拉强度相比于沉积棒料都明显降低,其中,第16层沉积层硬度最大为80HV,约为沉积棒料母材的55.6%;第1~8层沉积层硬度均匀在60HV。增材区水平(longitudinal direction,LD)方向第9~16层和1~8层的平均抗拉强度分别为243.0 MPa和219.3 MPa,约为母材的60.0%和52.9%;平均伸长率为19.4%和24.5%,分别约为母材的181.1%和229.0%。增材试样LD方向断裂模式均为韧性断裂。

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 6μm,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.