Note: This article involves a large number of welding terminology, there will be inaccuracies in the translation, please understand and welcome to point out!

    AKG TZ-7, equivalent: AWS A5.1 E7016 electrode, mild steel electrode, used for one-sided welding of pipelines and double-sided moulding welding, the use of small current single-sided welding, arc stability is very good, can be welded to mild steel and 490MPa level of high-strength steel pipe butt joints, and can be achieved by one-sided welding and double-sided moulding. The electrode belongs to low hydrogen type, when welding the root channel of pipeline and general structure, because it can realise one-sided welding and two-sided forming, so it can save the clearing welding, so that the welding efficiency can be improved.
    We dry the welding rod at 300~350℃ for 30~60 minutes before using alkaline welding rod. Not every unsuitable bevel can be welded, we are also selective, suitable current and bevel in order to get a beautiful back weld channel. Arc extinguish the arc pit to the side of the bevel in the arc break, the arc can be used to lead the arc plate or in the side of the bevel to lead the arc, keep the arc as short as possible.
    DC welding needs to use DC positive connection, that is, the electrode is connected to the negative pole, the earth wire is connected to the positive pole.
    The bottoming welding current is around 80-100.
    Welding rod in the bevel up and down slightly swinging, to be melted at the root to form a melt hole, the welding rod should be quickly on top and low arc, using a small diagonal serrated back and forth to transport the rod, the action should be fast, even, smooth.
    Be careful to observe the temperature of the molten pool and the shape of the molten hole to maintain the basic consistency, pay special attention to observe the length of the arc to melt the root of the thick-walled pipe, the size of the molten pool required 1/2 in the inside, 1/2 in the outside of the bevel, each time the arc to follow up the time of the molten pool is close to solidification is appropriate to follow up too quickly, the liquid molten pool increased, liquid metal is easy to flow down to form weld tumours, follow up too slowly, the liquid molten pool compressed inward, the liquid metal is not complementary In time, easy to form a depression in the back weld.
    Generally each time the liquid metal to send the time should be controlled in 1 ~ 1.5s.
    Listen to whether the arc strikes through the pipe bevel edge issued by the ‘flutter’ sound.
    According to the welding process gap contraction, through the appropriate arc length, electrode angle, welding speed and transport method of regulating the arc length and melt pool size, the iron accurately sent to the root of the bevel, the three fit together properly, you can achieve a good reverse shape.
    Close the arc, first in the molten pool above a molten hole, and then slowly bring the molten pool of iron back 10 ~ 15mm, in the bevel side of the arc, in order to slow down the solidification of the molten pool, to prevent the molten pool to produce cold shrinkage holes, and to make the joints to form a slope, in order to facilitate the next joints, at this time, pay attention to not in the centre of the weld molten pool back to the weld to collect the arc, in order to prevent the production of cold shrinkage holes, and even more can not be in the molten pool directly to collect the arc, otherwise it may be in the back of the weld molten pool surface cold shrinkage. Weld pool surface to produce cold shrinkage holes, become difficult to repair defects.
    Welding defect causes and solutions
(1) the root of the weld is not welded through
Reason: the blunt edge is too thick, the root gap is too narrow, the welding current is too low, the bevel angle is too small, the arc is too long.
Countermeasures: trimming the shape of the bevel, increase the current, the electrode more into the bevel.
(2) concave
Reason: the welding current is too large, the arc is too long, the root gap is too wide, the bevel angle is too small.
Countermeasures: reduce the welding current, the electrode more into the bevel, improve the welding speed.
(3) not fused
Reason: the bevel angle is too small, the welding speed is too fast, the welding channel is very irregular.
Countermeasures: trimming bevel and bevel shape, increase welding current, reduce welding speed. Use the grinding wheel to trim the irregular welding channel.
(4) burn through
Reason: the root gap is too large, the blunt edge is too thin.
Countermeasures: reduce the welding current, trimming the shape of the bevel, improve the welding speed.
(5) slag
Reason: residual slag, welding current is too small, unstable transport bar.
Coarse adjustment of the depth of fusion should be carried out through the control of welding current.
–The smaller the angle of the welding rod, the shallower the depth of fusion.
–The closer the arc position is to the hole, the deeper the depth of fusion.
–The more the electrode extends into the bevel, the deeper the depth of fusion.
The depth of fusion is usually shallower in the upward welding position, and the reverse side is prone to depression. Therefore, the electrode should be brought further into the bevel and moved more quickly.
Grinding the joint of the weld lines Before joining the weld lines in order to obtain a smooth reverse weld line, it is necessary to grind the weld lines to a minimum.
To make a smooth reverse weld line before joining the weld lines, start the arc on the previous weld line and then move to the joining area.