双层金属管用半固态坯料制备及二次加热

Preparation and Reheating of Semi-solid Billets for Double-layer Metal Tube

采用机械搅拌的方法制备半固态浆料,利用专门的制坯模按照预定尺寸制得能够使用于挤压成形双层金属管的半固态AZ91镁合金棒料和A356铝合金坯料,研究制备工艺以及二次加热温度及保温时间对半固态坯料微观组织的影响。通过组织分析,对双层金属管用AZ91镁合金坯料和A356铝合金坯料的触变性进行了研究。结果表明,双层金属管用AZ91镁合金坯料最佳尺寸为24mm,二次加热温度为560℃,保温时间为21min;A356铝合金环状坯料最佳尺寸壁厚为8mm,二次加热温度为600℃,保温时间为20min时,此时能得到适合于进行半固态触变成形的球化组织。

Semi-solid AZ91 Mg alloy slurry and A356 aluminum alloy slurry were prepared by mechanical stirring,which was used to produce Mg alloy rod and Al alloy billets for extruding double-layer metal tube by special billet-making-mould with a fixed size. Effects of processing parameters and reheating temperature as well as hold time on microstructure of semi-solid billets were observed to understand the thixo-forming behavior of two kinds of billets. The results reveal that it is beneficial to the formation of spheroidized structure in semi-solid when AZ91 magnesium alloy with 24 mm in diameters is reheated at 560℃ for 21 min and A356 ring billets with 8 mm in wall thickness is reheated at 600 ℃ for 20 min.