Effect of Tool Geometry and Heat Input on the Hardness, Grain Structure, and Crystallographic Texture of Thick-Section Friction Stir-Welded Aluminium
Effect of Tool Geometry and Heat Input on the Hardness, Grain Structure, and Crystallographic Texture of Thick-Section Friction Stir-Welded Aluminium
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DOI：
10.1007/s11661-018-4996-2
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发表时间：
2019-01-01
影响因子：
2.8
通讯作者：
Threadgill, P. L.
中科院分区：
文献类型：
--
作者：
Ahmed, M. M. Z.;Wynne, B. P.;Threadgill, P. L.
研究了刀具几何形状对32 mm厚AA6082搅拌摩擦焊接头组织和晶体织构的影响。锥形探头工具的使用导致熔核从顶部到底部的晶粒度有显著差异，而平行探头工具在整个熔核中产生均匀的晶粒度。熔核中的晶粒度反映了所经历的变形量和以应变率表示的变形速度。提出了一种计算铝在搅拌摩擦焊过程中应变速率的方法，得到了217~362s(-1)的应变值。应变率可以是均匀的，也可以根据所用工具的类型随接头厚度而变化。锥形刀具产生了应变速率的变化，而平行刀具的应变速率始终是均匀的，这可以解释每种情况下获得的晶粒结构。刀具几何形状也影响了织构的发展，锥形刀具使局部剪切参照系倾斜了与锥角相等的法线方向。
The effect of tool geometries on the microstructure and crystallographic texture of 32-mm-thick friction stir-welded AA6082 has been investigated. The use of a tapered probe tool results in a significant variation in the grain size from the top to the base of the nugget, whereas parallel probe tools produce a uniform grain size throughout the nugget. The grain size in the nugget reflects the amount of deformation experienced and the speed of deformation expressed in terms of strain rate. An approach is proposed to calculate the strain rate during FSW of aluminum for which values between 217 and 362s(-1) were obtained. The strain rate can be either uniform or varied through the joint thickness based on the type of tool used. The tapered tool produces a variation of the strain rate, whilst the parallel tool has a uniform strain rate throughout, which can explain the obtained grain structure in each case. The tool geometries also influenced texture development with the tapered tool producing a tilt of the local shear reference frame by an angle to the normal direction equal to the taper angle.