碳纳米管对TC4钛合金激光焊焊缝成形和组织的影响

Effect of Carbon Nanotubes on Weld Formation and Microstructure of TC4 Titanium Alloy Laser Welding

选取羟基化多壁碳纳米管作为表面活性剂对TC4钛合金进行活性CO 2激光焊接,焊后测量并计算了焊缝的熔深、熔宽及深宽比,观察分析了焊缝显微组织,测定了接头硬度和焊缝的物相组成。结果表明:TC4钛合金表面涂覆质量分数为4%的碳纳米管溶液,形成的涂覆层均匀致密;在给定焊接参数条件下,该涂覆层可使焊缝熔深增加约6%,熔宽降低约4%,深宽比增加约10%;涂覆碳纳米管可以增加激光吸收率,使得焊缝温度升高、冷却速率增大,因而涂覆碳纳米管的焊缝β晶粒较细,晶内的α′相较未涂覆碳纳米管的短小;碳纳米管对焊缝硬度和焊缝的物相组成无明显影响。

Hydroxylated multi walled carbon nanotubes(MWCNTs)were selected as the surface activating flux to carry out the CO 2 laser welding of TC4 titanium alloy.The penetration,width and ratio of depth to width of the weld joint were measured and calculated.And the microstructure,microhardness and phase composition of the weld joint were also studied.The results show that the coating formed with the solution of 4%MWCNTs is uniform and dense on the surface of TC4 titanium alloy.The presence of the coating can increase the penetration of weld joint by about 6%and reduce the width by about 4%.The ratio of depth to width is increased by about 10%under the condition of given welding parameters.It is suggesting that MWCNTs can increase the laser absorption.Theβgrain of the weld joint coated with MWCNTs is fine andα′phase in the crystal is short because of the rise in welding temperature and cooling rate.In addition,MWCNTs didn't show an obvious effect on the microhardness and phase composition of the weld joint.