中文摘要：

多边形异形管被广泛应用在航空等领域,为解决其角接头无填充焊接问题,分析了激光热源角接头形式,控制能量输入得到完全熔透模式。采用焊件背面辅以支撑以及先点焊后缝焊的方法,实现多边形异形管激光无填充焊接。试验得到连接质量满足技术要求的三边形、五边形和六边形异形管。角接头激光无填充焊接方法,为角接头焊接和异形管的成形提供理论基础和试验依据。

英文摘要：

Polygon-shaped tubes are widely used in aviation area. To solve the problem on the welding of fillet joint in polygon-shaped tubes,laser welding without filler wire was studied.Joint design was analyzed,exactly penetration mode and auxiliary support were adopted too.Fillet joints using austenitic stainless steels with the angles 60°,108°,120° were welded on a JK701H Nd：YAG pulse laser machining center.Based on the assessment of weld geometries,fillet joints were measured by CCD.It is found that weld profiles are closed flat,ripples on the surface are regular,weld size increases from 1.16 mm to 1.40 mm with the increase of the angels of fillet joint from 60° to 120°,and weld thickness from 0.44 mm to 0.58 mm.Three polygon-shaped tubes with triangle,pentagon and hexagon cross section,were obtained.The results show that laser welding of fillet joint without filler wire has important theory and application values to fillet joint welding and manufacturing of polygon-shaped tubes.