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Evaluation of the nature of internal defects, causes of defects and preventive measures ②

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Slag inclusion




The echo signal of point-like slag inclusion is similar to that of point-like stomata. The echo signal of strip-like slag inclusion is mostly sawtooth and the amplitude is not high. The ultrasonic flaw detection waveform is mostly dendritic, with small peaks on the edge of the main peak, and the probe translation amplitude varies. The reflected wave amplitudes are not the same when the direction is detected.



The reasons for such defects are: the welding current is too small, the speed is too fast, the slag is too late to float, the welded edges and the welds of each layer are not cleaned cleanly, the chemical composition of the metal and welding materials is improper, and the sulfur and phosphorus content is relatively high. Wait.



Preventive measures include: the correct selection of welding current, the groove angle of the weldment should not be too small, the groove must be cleaned before welding, the welding slag must be cleaned layer by layer during multi-layer welding; and the welding speed of the transport angle should be reasonably selected.