For straight joint submerged arc welding pipe defective component of the sample, by ultrasonic flaw detector by hand validate the defects in the weld joint setting, utilize the method of machining exercise defects in the weld cross section, after grinding, brightening, etching metallographic specimen.Through the evaluation of the metallographic evaluation, it is located that the weld slag of the bonded pipe in the thick wall surface lies in the position of the fusion line of the inside as well as outside welds, as displayed in number.

Slag is the slag that stays inside the weld.From the theory analysis, automatic submerged arc bonded causes of slag has the complying with 3 factors: resources (consisting of the parent steel, welding wire, flux) of incorporation is more.Clean up between layers of welding.The application of the welding process criteria is bad, and also it is not conducive to the emergence of slag.

According to the production qualities of the welded pipeline in the straight joint, it is possible to eliminate the reason that the welding seam is not clean in the multi-layer welding layer.For steel sheet more additions in the raw material and make the slag addition of weld, take assessment before welding material, replacement, new actions such as filler steels and also changes.

Therefore, the main factor for the welding process of the welded wire is the inappropriate criteria of welding process.The welding process criteria of thick wall surface seam welding tube are mainly: line power, welding current, welding voltage, welding rate, cord spacing, groove size and so forth.

To do thorough analysis from the elements of welding metallurgy: weld combination line root cause of slag is mainly fusion line temperature is also low, make the liquid slag can not afford time to precipitate; The result is that the temperature level of the fuse is also low since the height temperature level is also reduced or too fast.In welding drunk of groove kind, on both sides of the origin of the weld the density of the central region is far much less than the density of the cooling rate is smaller than on both sides of the numerous, therefore, very easy slag, on both sides of the weld root., various other problems being the same with the groove Angle and depth of molten weld depth increases, the groove increase with the decline of the dimension of the blunt edge, it raises with the reduction of the welding speed.When the line energy is constant, as the weld infiltration boosts, the highest temperature level of the fuse line decreases, and the weld is reliant generate slag.

In the astm a53 erw steel pipeline multi-wire buried arc welding, the welding speed has a huge effect on weld deepness as well as melt width, and the faster the welding speed, the reduced the melting deepness as well as the melting width.Conversely, the bigger the larger.

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