不同氟化物对钛合金A-TIG焊接成形和组织的影响

Effect of Different Fluorides on Weld Formation and Microstructure in A-TIG Welding of Titanium Alloy

采用9种氟化物对TC4钛合金进行A-TIG焊接实验,并利用高速摄像机和汉诺威焊接质量分析仪采集焊接过程中的电弧形态和电压信号,对焊后焊接接头的成形参数和宏观组织进行了对比分析。结果表明:9种氟化物中MgF_2活性剂增加焊缝熔深效果最显著,达到无活性剂时的2倍,KF居次,但Li F可降低焊缝熔深;相比MgF_2活性剂,KF活性剂的熔宽小,热影响区宽度窄,接头总宽度小;Na F活性剂获得了最小的热影响区宽度;NaF、KF、MgF_2、Al F3活性剂焊缝的β柱晶生长方向与焊缝中心轴线的倾角比其它活性剂大,柱晶长度由熔深大小决定,柱晶宽度尺寸排序:AlF_3>KF>MgF_2>NaF;热影响区粗晶区晶粒大小排序:MgF_2>NaF>AlF_3>KF。

Nine kinds of fluorides were used for A-TIG welding of titanium alloy.Welding arc shape and electrical signals were collected by the high-speed cameras and Hannover analyser in the process.After welding,macrostructure of the welded joint was analyzed.The results show that MgF2 has an apparent effect in increasing the weld penetration,which is 2 times the depth of weld without flux.KF is in the second place.But,Li F could decrease the weld penetration.Compared with MgF2,KF has a small weld width,narrow HAZ width and total joint width.Na F obtains the minimum HAZ width.The angle of NaF,KF,MgF2 and Al F3 between columnar crystal growth direction and weld center axis is bigger than that of other fluorides.The length of the column crystal size is determined by the size of penetration,the width variation law is AlF3〉KF〉MgF2〉NaF and the grain size of coarse grain area in HAZ is MgF2〉NaF〉AlF3〉KF.