During pipeline automatic welding, undercut is a common welding defect that not only affects the appearance quality of the weld but also potentially impacts the strength and reliability of the welded joint. Therefore, conducting an in-depth analysis of undercut phenomena and adopting corresponding preventive measures are of great significance for ensuring welding quality and engineering safety.
Undercut refers to a depression or groove formed in the base material along the weld toe. This defect occurs when the arc melts the edge of the weld's base material without sufficient molten metal to fill the gap left behind. Undercut reduces the effective cross-sectional area of the base material and may cause stress concentration at the undercut location. Especially in the welding of low-alloy high-strength steel, the edge tissue of the undercut is more prone to cracking. Therefore, the presence of undercut directly affects the strength and reliability of the welded joint.
The causes of undercut in pipeline automatic welding are mostly due to improper selection of welding process specifications, specifically manifested in the following aspects:
Excessive welding current: When the welding current is too high, the arc energy increases, causing the base material at the weld edge to melt too quickly without timely replenishment of molten metal, resulting in undercut.
Excessive arc length: An excessively long arc distributes arc heat unevenly, causing uneven melting of the base material at the weld edge. At the same time, the increased arc blowing force can easily blow away the base metal without filling the molten pool, forming undercut.
Inappropriate welding speed: When the welding speed is too fast, the molten metal fails to fully fill the depression at the weld edge; when the welding speed is too slow, the molten iron in the middle of the weld may overheat and drop, also leading to undercut.
Uneven welding torch oscillation: Uneven oscillation of the welding torch results in uneven melting of the weld edge and insufficient filling of molten metal, thereby producing undercut.
Undercut defects can be avoided and eliminated by adjusting and optimizing the welding process. During welding, select appropriate welding current and welding angle, do not extend the arc too far, oscillate the welding electrode uniformly, and spend slightly longer at the edge of the groove while moving faster in the middle to reduce undercut phenomena in the weld.
In manufacturing, it is crucial to reduce and avoid such issues. Pipeline automatic welding equipment can help improve the pass rate of welding and effectively enhance welding efficiency. MWG series open-type pipe-to-pipe welding equipment from mwelding, as a professional medium-wall thickness pipeline automatic welder, is widely used in project construction sites, and its excellent operating performance has received praise from numerous customers.
This equipment is mainly used for welding medium-thickness pipes such as stainless steel, carbon steel, titanium alloy, with wall thicknesses ranging from 2 to 10mm. The equipment is equipped with an intelligent digital welding control system with automatic arc length, lateral oscillation, and welding speed feedback functions. It achieves good molding, and the weld meets Grade II flaw detection requirements. With German-imported core components, it is precise, efficient, durable, and cost-effective. It features one-click operation and is easy to learn. The portable body allows for flexible operation and supports customized one-to-one configurations, along with full-process technical services.
Applicable Pipe Diameters:
MWG-90: Suitable for pipe diameters Φ19-89mm
MWG-170: Suitable for pipe diameters Φ63-168mm
MWG-230: Suitable for pipe diameters Φ130-230mm
MWG-325: Suitable for pipe diameters Φ159-325mm
Welding Types:
Straight pipe-to-straight pipe, straight pipe-to-clamp, straight pipe-to-tee, straight pipe-to-elbow, large U-bend, etc.
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For more products and services such as automated pipe-to-pipe welding machines, automated pipe-to-plate welding machines, automated circumferential welding machines, hot-wire surfacing systems, please call: +86 18918961606 or visit the official website of Shanghai Mwelding: https://www.mwelding.com.cn
