高效搅拌摩擦钎焊制备铝/钢双金属复合板的可行性研究

Feasibility of Efficiently Fabricating Al/Steel Bimetal Composite by Friction Stir Brazing

为验证采用作者开发的免磨损无针式搅拌摩擦钎焊(简称FSB)制备铝/钢防腐双金属复合板的可行性,研究了采用不同直径搅拌头所制备的复合板的表面成形、界面组织与性能特点.结果表明:当搅拌头直径过小(20 mm以下)时,因热输入不足使焊道表面起始端粗糙,且试样在较低载荷下便断裂于原始界面;当采用中等直径(20 mm)搅拌头时,焊道表面成形光滑,在中等焊速(150mm/min)下可获得致密的结合及良好的性能;当采用大直径(40 mm)搅拌头时,飞边陡然加剧,适当减小压入深度或提高焊速可减小飞边;由于强烈的热力联合作用,即使在高焊速(300 mm/min)下也可以获得致密的界面结合,钎料锌几乎全被挤出.因此,采用大直径搅拌头、高焊速FSB制备铝/钢双金属复合板是可行的.

To verify the feasibility of efficiently fabricating Al/steel corrosion-resistant bimetal composite by the authors＇ friction stir brazing （FSB） process, in which a tool without probe is used to eliminate severe wear of probe by steel, the characteristics of bead surface forming, interfacial microstructure and property of FSB joint of Al/steel were investigated with tools of different sizes. For small tool of a diameter less than 20 mm, rough bead surface forming tended to occur at the just starting portion, simultaneously, joints fractured along initial interface under low load. For medium tool of 20 mm diameter, both dense interracial structure and excellent bonding were obtained at medium traverse speed （150 mm/min）. For larger tool of 40 mm diameter, flash became extremely obvious. In this case, the flash could be reduced by decreasing plunge depth or increasing traverse speed, while dense interracial structure with little filler metal of Zn and excellent bonding could still be obtained even at high traverse speed （300 mm/min） due to the combination of enhanced heating and forging force. Therefore, Al/steel metallic layered composite can be effectively fabricated by FSB with larger tool and higher traverse speed.