脉冲宽度对超薄TiNi/不锈钢激光焊接头TiNi侧界面的影响

Effect of pulse width on TiNi side interface of laser welded joint of TiNi/ stainless steel

摘要:

添加Ni做为填充材料是抑制TiNi/不锈钢异种材料激光焊接头裂纹从而实现其良好连接的方法之一,但填充金属Ni与母材TiNi合金的成分差异会形成界面区,焊接热输入对界面区的组织形貌有很大的影响,进而会影响整个接头的力学行为。本文在厚度为0.2mm的TiNi合金/321不锈钢异种材料激光微焊接时,预置Ni做为填充材料,获得了TiNi合金/Ni/321不锈钢激光焊接头,研究了激光脉冲宽度对焊接接头TiNi侧界面的影响。结果表明,不同脉冲宽度下,TiNi合金侧界面区均由宽度不等的TiNi共晶层和TiNi₃金属间化合物层组成；随着脉冲宽度的增加,TiNi共晶层平均宽度逐渐减小,TiNi₃金属间化合物层平均宽度逐渐增加；界面区显微硬度随脉冲宽度的增加逐渐升高。TiNi母材熔化量和Marangoni流动的改变是影响接头该侧界面区宽度及显微硬度的主要原因。

Abstract:

The addition of Ni as filler is one of the methods to restrain the crack of TiNi / stainless steel dissimilar material laser welding joint and realize its good connection, but the difference between filler metal Ni and base metal TiNi alloy will form the interface area, the welding heat input has a great influence on the microstructure and morphology of the interface area, which will affect the mechanical behavior of the whole joint. In this paper, TiNi alloy / Ni / 321 stainless steel laser welding joint with thickness of 0.2mm was obtained by using Ni as filler material in laser micro - welding. the effect of laser pulse width on the TiNi side interface of the welding joint was studied. The results show that, the interface zone of TiNi alloy side under different pulse width is composed of TiNi eutectic layer and TiNi3 intermetallic layer with different width.With the increase of pulse width, the average width of TiNi eutectic layer gradually decreases, the average width of TiNi3 intermetallic compound layer increases gradually, and the microhardness of interface zone increases with the increase of pulse width. The change of the melting amount of TiNi and the flow of Marangoni is the main reason that affects the width and microhardness of the interface zone.