All kinds of welding defects of TIG welding of aluminum and its alloy are the same as those of other arc welding, and some are special.The welding quality of TIG welding of aluminum and its alloy is related to the preparation before welding, the purity of protective gas, the accuracy of welding parameters, the proficiency of quality operation technology of electrode materials, welding power and other factors.The causes of common defects and preventive measures are as follows:
TIG welding crack defect
The reasons are as follows: unreasonable structural design, excessive concentration of welding seams, and excessive restrained stress of welding joints.The weld pool is overheated and the alloy elements are burned out.The arc is closed too fast and the welding wire is withdrawn too fast, which results in the arc pit is not filled up.Improper selection of materials, for example, when Mg content is less than 3%,Fe, S and other impurities exceed the standard, easy to cause cracks. When the melting temperature of welding wire is too high, it is easy to cause the liquefaction crack in the heat-affected zone.
The preventive measures are as follows: correct design of welding structure, reasonable arrangement of welding seams, avoiding the stress concentration as far as possible, and reasonable selection of welding sequence. Decrease welding current or increase welding speed.The correct operation technique of arc closing is to add the drawing plate or fill the arc pit with the current attenuation device.Choose the right welding materials.
TIG pores defect in welding
The main causes are: base material or wire oil, dirt, rust, dirt other dirt. Low purity , poor gas protection. Air path is not clean, have leak, plug, etc.Improper selection of welding parameters.In the welding process, the welding pool is not well protected, the arc is unstable, the arc is too long, the tungsten electrode is extended too long, etc.
Preventive measures include: thoroughly clean the weld area and welding wire before welding.Do not lift the nozzle too high, do not make the welding speed too large, use qualified protection gas.Replace the gas pipeline in time.Reasonable selection of welding parameters.To protect the pool measures, such as welding site to have a windshield;Give rare proper warm-up etc.
TIG lacking of penetration defect
The main reasons are: welding current is small, arc length is too long, welding speed is too fast.The assembly clearance is so small, the blunt edge is too large and the break. Angle is so small.The presence of oxides on the surface or between layers is not removed.The dip Angle of welding gun and wire is not correct.
Preventive measures include: correct selection of welding parameters.Prepare welding joints and cracks accurately.Strengthen cleaning before welding and cleaning between layers.Improve operational techniques.
TIG welding undercut defect
The main reasons are: welding current is too large, arc voltage is too high. Too fast welding speed, extremely little filler wire. Skilled operation technology department, welding torch swing uneven, etc.
Preventive measures include: adjust the appropriate welding current and arc voltage.Live ammunition increases wire feed speed or decreases welding speed.Improve the operation technology, try to make the welding gun swing evenly.
TIG welding burn through defect
The main reasons are: too much current.The welding speed is slow.Groove form and assembly clearance are not reasonable.Welders have poor skills.
Preventive measures include: appropriate reduction of welding parameters.Improve welding speed.Reasonable fracture preparation and adjustment of assembly clearance.For example, increase the blunt edge, reduce the root clearance.Improve operational techniques.
TIG oxidation defect
The main reasons are: tungsten electrode and nozzle different center.Protect gas flow stingy road unclean, etc.
Preventive measures are: replace the nozzle or tungsten electrode clip, is the tungsten electrode and nozzle basically concentric.Adjust the protection gas flow in a reasonable range.Remove gas path fault or replace the air pipe, or even replace the welding gun assembly.
