In the use of argon arc welding austenitic stainless steel pipe, due to the role of various accidental or inevitable factors, there will inevitably be some poorly welded substandard products. Analysis of its causes and the development of remedial methods is a means of improving the rate of finished products. This article on the welding of some unqualified phenomenon to make an analysis, and put forward some remedial methods, for reference.
First, the surface porosity
Causes: surface porosity is generally caused by the use of non-conforming welding consumables or workpiece surface cleaning does not meet the requirements or operation when the angle of the welding rod is not correct or the construction environment does not meet the requirements.
Prevention: Use the correct welding consumables, clean the workpiece before welding and choose a suitable welding angle.
Remedy: Clean up the defect with an angle grinder or welder’s chisel. If the weld surface is not shaped to meet the standard requirements after the defect has been removed, the weld must be made up again. Welding must take into account the location of the arc and arc extinguishing; welding should be re-polished after completion to clean up the weld, so that the transition is smooth.
Second, the weld is not filled
Reason: The cause of unfilled weld seam is generally caused by poor responsibility of the welder or improper form of workpiece bevel.
Prevention: Select a suitable workpiece bevel.
Remedy: The weld must be re-filled. The necessary cleaning should be carried out before the filler weld, and the position of the arc initiation and arc extinguishing must be taken into account when the filler weld is completed; the weld should be re-polished and cleaned up after the filler weld to make the transition smooth.
Three, weld residual height exceeds the standard
Reason: The reason for the defect of excess weld height is generally caused by improper operation method or improper layout of interlayer welding channel.
Prevention: reasonable layout of interlayer welding channel.
Remedial measures: use angle grinder or welder’s chisel to polish and clean the defect so that the transition is smooth and the weld meets the standard requirements.
Four, weld width difference exceeds the standard
Reason: The reason for the defect of exceeding the width of the weld seam is generally caused by the insufficient skill level of the welder or the lack of responsibility or improper form of bevel.
Prevention: Select the appropriate bevel.
Remedy: Use an angle grinder or welder’s chisel to polish and clean the defect so that the weld meets the standard requirements. Patch welding should be carried out if necessary. The necessary cleaning should be carried out before the filler weld, and the position of the arc initiation and extinguishing must be taken into account when the filler weld is completed; the weld should be reground and cleaned after the filler weld to make the transition smooth.
V. Biting edge
Causes: Bite edge defects are caused by improper operation of the welder or too much current, or welding electrode, welding torch angle improper, so that the melted base material is not filled by the weld metal.
Prevention: preventive measures, the correct choice of current, welding rod (gun) angle and welding speed, both sides of the weld to properly extend the dwell time.
Remedial measures: use angle grinder or file to file and grind the biting edge defects, the slight biting edge, such as defects after removal, and to achieve a smooth transition and meet the standard requirements are considered qualified, the deeper biting edge, it should be repaired after grinding to fill the welding. When welding, attention should be paid to the arcing and arc extinguishing, slightly increasing the current and filling the biting pits. The weld should still be polished and rounded to the base material in accordance with the regulations.
Causes: The causes of cracking are generally caused by improper selection of the welding process or welding process workpiece stained with oil, water and other contaminants or workpiece in the welding mouth in a strong external stress state.
Prevention: Thoroughly clean the surface of the weld before welding
Remedy: Use angle grinder to polish and clean the defect, and carry out PT colouring test to check. Ensure that there are no cracks before welding. The welding can be carried out by both GTAW and SMAW methods; the necessary cleaning should be carried out before the welding is carried out, and the position of the arc initiation and extinguishing must be taken into account when welding; the weld should be reground and cleaned after the welding is completed to make the transition smooth.
If necessary, a spectroscopic check of the weld should be carried out to confirm the correct choice of welding process, and the weld should be cut and rewelded if the welding process is not selected properly.