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Fabrication of Thin Aluminum Alloy Slab and Technological Development for Its Application

铝合金薄板坯的制备及其应用技术开发

基本信息

批准号：
10555228
负责人：
KAMADO Shigeharu
金额：
$ 1.73万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The main purpose of this study is to fabricate a thin aluminum alloy slab using electromagnetic casting(EMC), which will enable us to make a thin plate only by cold rolling without hot rolling and intermediate annealing, . Firstly relationships between outward appearances and manufacturing conditions were investigated. Fabrication of billets as raw materials for semi-solid forming were also tried to confirm the characterization of EMC.Furthermore, mechanical properties of the rolled plates and the semi-solid formings manufactured using the EMC slabs and billets were evaluated. Obtained results are summarized as follows ;(1) At the early stage of continuous casting the meniscus thickness largely depends on the thickness of bottom block and as a result the fabricated slab thickness is nearly equal to the thickness of bottom block. When the thin slab is fabricated under a casting speed of 960mm/min and a water cooling rate of 20L/min, it has a uniform thickness of 7mm, smooth surface and … More equiaxed grains. Application of EMC to the fabrication of thin slab makes the microstructure to be very fine up to dendrite arm spacing of 10μm due to a large cooling rate caused by the thin thickness and direct water cooling. Such a fine microstructure leads to a good rolling ability up to the rolling ratio of 75% with no edge cracks.(2) Crystallized compounds increase with increase in Fe content and cooling rate, but the tensile properties of the rolled thin plate are improved because the compounds are fine and distribute uniformly and, therefore, useful for the dispersion strengthening and for refining the recrystallized grains. As a result, even when 5052 aluminum alloy contains a large amount of Fe as an impurity, tensile properties of heat-treated sheets of directly cold rolled EM cast thin slabs satisfy JIS requirements if Mg content is reduced to 2.05% which is smaller than the lower limit specified by JIS for 5052 aluminum alloy. This indicates that the application of EMC to the fabrication of the thin slab is very useful for reduction of bad influences by impurities.(3) Addition of a grain refiner and application of EMC process ensures the production of sound billets with fine and equiaxed grain throughout the entire structure. Upon semi-solid forming using the billets at optimum temperatures, fine and nearly spherical solid particles distribute uniformly throughout the formed specimens and an increase in fluidity even for thin parts are observed for all investigated alloy. Furthermore, tensile properties of T6-treated specimens of semi-solid formed samples of 7475 and A357 aluminum alloys are close to those of the forged samples of 7475 wrought alloy and A357 casting aluminum alloy sample thixocast using billets fabricated by DC casting with electromagnetic stirring, respectively. Less

本研究的主要目的是利用电磁铸造（EMC）制造薄铝合金板坯，这将使我们能够仅通过冷轧而无需热轧和中间退火来制造薄板。首先研究了外观与制造条件之间的关系。此外，还尝试了半固态成形坯料的制备，以证实EMC的特征。此外，还对使用EMC板坯和坯料制备的轧制板材和半固态成形件的力学性能进行了评价。研究结果表明：（1）在连铸初期，弯月面厚度主要取决于底块厚度，铸坯厚度与底块厚度接近。当拉速为960 mm/min，水冷速度为20 L/min时，薄板坯厚度均匀，为7 mm，表面光滑， ...更多信息等轴晶粒电磁铸造技术应用于薄板坯的制备，由于薄板坯厚度薄，直接水冷，冷却速度快，使组织非常细小，枝晶臂间距可达10μm。这种精细的显微组织导致良好的轧制能力，高达75%的轧制比，没有边缘裂纹。(2)结晶化合物随Fe含量和冷却速度的增加而增加，但轧制薄板的拉伸性能得到改善，因为化合物细小且分布均匀，因此有利于弥散强化和细化再结晶晶粒。结果，即使5052铝合金含有大量的Fe作为杂质，如果Mg含量降低到2.05%，即小于JIS对5052铝合金规定的下限，则直接冷轧EM铸造薄板的热处理板的拉伸性能满足JIS要求。这表明，电磁兼容技术在薄板坯生产中的应用，对减少杂质的不良影响是非常有益的。(3)加入晶粒细化剂和应用EMC工艺，确保了整个组织中具有细小和等轴晶粒的优质坯料的生产。在最佳温度下使用坯料进行半固态成形时，细小且接近球形的固体颗粒均匀地分布在整个成形试样中，并且观察到所有研究合金的流动性增加，即使对于薄零件也是如此。此外，7475和A357铝合金半固态成形试样的T6处理试样的拉伸性能分别接近于使用通过直流铸造与电磁搅拌制造的坯料进行触变铸造的7475锻造合金和A357铸造铝合金试样的锻造试样的拉伸性能。少