Al-Helal Kawther, Patel Jayesh B, Scamans Geoff M, Fan Zhongyun
Brunel Centre for Advanced Solidification Technology, Brunel University London, London UB8 3PH, UK.
Innoval Technology Limited, Beaumont Cl, Banbury OX16 1TQ, UK.
Materials (Basel). 2020 Dec 16;13(24):5740. doi: 10.3390/ma13245740.
AA6111 aluminum automotive body-sheet alloy has been formulated from 100% Taint Tabor scrap aluminum. Direct chill casting with and without high shear melt conditioning (HSMC) was used to produce the AA6111 alloy billets. Both homogenized and non-homogenized billets were extruded into sheets. The optical micrographs of the melt conditioned direct chill (MC-DC) samples showed refined equiaxed grains in comparison to direct chill (DC) cast and direct chill grain refined (DC-GR) samples. Optical metallography showed extensive peripheral coarse grain (PCG) for the DC, DC-GR and MC-DC planks extruded from the homogenized standard AA6111 billets while planks extruded from modified AA6111 billets (with recrystallization inhibitors) showed thin PCG band. The co-addition of recrystallization inhibitors Mn, Zr, and Cr with elimination of the billet homogenization step had a favorable impact on the microstructure of the AA6111 alloy following the extrusion process where a fibrous grain structure was retained across the whole section of the planks. The mechanical properties of as-cast planks extruded from non-homogenized billets were similar to those extruded from homogenized billets. Eliminating the homogenization heat treatment step prior to extrusion has important ramifications in terms of processing cost reduction.
AA6111汽车车身铝板合金由100%的泰恩特伯废铝制成。采用有和没有高剪切熔体处理（HSMC）的直接水冷铸造工艺来生产AA6111合金坯料。将经过均匀化处理和未经均匀化处理的坯料都挤压成板材。与直接水冷（DC）铸造和直接水冷细化晶粒（DC-GR）的样品相比，熔体处理直接水冷（MC-DC）样品的光学显微照片显示出细化的等轴晶粒。光学金相分析表明，从均匀化标准AA6111坯料挤压出的DC、DC-GR和MC-DC板材存在大量周边粗晶（PCG），而从改性AA6111坯料（添加了再结晶抑制剂）挤压出的板材显示出较薄的PCG带。再结晶抑制剂锰、锆和铬的共同添加以及坯料均匀化步骤的取消，对挤压过程后AA6111合金的微观结构产生了有利影响，此时板材的整个截面都保留了纤维状晶粒结构。从未经均匀化处理的坯料挤压出的铸态板材的力学性能与从经过均匀化处理的坯料挤压出的板材相似。在挤压之前取消均匀化热处理步骤在降低加工成本方面具有重要意义。
