冷喷涂沉积Si中间层对铝钢连续驱动摩擦焊接头组织与性能的影响

Effect of cold spray deposition of Si interlayer on microstructure and properties of continuous drive friction welding joint

摘要:

在使用连续驱动摩擦焊焊接铝钢接头时,由于其焊接端面具有绕轴旋转的特点,焊接时会出现线速度沿半径方向不均的现象,使得焊接摩擦扭矩及产热不均匀,同时因为铝钢间的溶解度较低,这导致接头界面会出现厚度不均匀的铝钢金属间化合物,影响接头整体力学性能。冷喷涂沉积Si中间层可以与铝、钢达到良好的结合,减少硬脆Fe-Al金属间化合物的产生,形成性能良好的Fe-Al-Si 金属间化合物,改变接头结合方式。本文采用冷喷涂法将Si粉末沉积到Q235钢棒端面形成约20μm厚的中间层,使用连续驱动摩擦焊与1060铝棒进行焊接。对比分析Si中间层的添加对接头焊接过程中的摩擦扭矩、焊接温度,以及接头力学性能、界面IMCs的形貌及性质的影响。结果表明：Si中间层的添加减小了铝/钢界面的摩擦系数,降低了焊接接头摩擦扭矩及峰值温度,进而使得金属间化合物层的厚度降低；界面形貌呈犬牙交错状,接头出现了机械嵌合,增加了接触面积；金属间化合物主要成分Fe2Al5和Fe3Al被力学性能较好的Al2Fe2Si3、Al0.5Fe3Si0.5所替代；接头各位置弯曲角度平均提高59°,其韧性明显增强,力学性能的不均匀性降低。

Abstract:

When welding aluminum-steel joints using continuous drive friction welding, the welding end face has the characteristic of rotating around the axis, and the phenomenon of uneven linear velocity along the radius direction will occur during welding, resulting in uneven friction torque and heat production. At the same time, because the dissolution rate between aluminum and steel is low, this will lead to the formation of a non-uniform aluminum-steel intermetallic compound at the joint interface, which affects the overall mechanical performance of the joint. The cold spray deposition Si interlayer can achieve good bonding with aluminum and steel, reduce the production of brittle Fe-Al intermetallic compounds, form a good performance Fe-Al-Si intermetallic compound, and change the joint bonding method. In this paper, cold spraying method was used to deposit Si powder on the end face of Q235 steel rod to form a 20um thick interlayer, and then continuous drive friction welding was used to weld with a 1060 aluminum rod. The effect of adding the Si interlayer on the friction torque, welding temperature, mechanical properties of the joint, and the morphology and properties of the interface intermetallic compound was compared and analyzed. The results showed that the addition of the Si interlayer reduced the friction coefficient of the aluminum/steel interface, reduced the friction torque and peak temperature of the welded joint, and further reduced the thickness of the intermetallic compound layer. The interface morphology was interlaced with each other, and the joint had mechanical interlocking, which increased the contact area. The intermetallic compound was mainly composed of Fe₂Al₅ and Fe₃Al replaced by Al₂Fe₂Si₃, Al_0.5Fe₃Si_0.5 with better mechanical properties. The average bending angle of the joint increased by 59°, and its toughness was significantly improved, and the uniformity of the mechanical properties was reduced.