Analysis of conventional technologies during welding processing of stainless steel plates

When processing and welding stainless steel plates, although various welding processes often dazzle the candidates, the essence of these processes are the same. Let’s talk about the conventional technologies of stainless steel plate welding processes.

The first is to strike the arc. The arc must be struck in the groove or on the arc strike plate. The arc strike point must be fused during welding. It is not allowed to strike the arc outside the groove. Arc strike marks and super-start arc craters are prone to corrosion, so they must be thoroughly polished off. Do not start welding from the tack welding point. The penetration depth should be shallow when starting welding. If the tack weld is not repaired and fused, it will easily cause welding defects.

In addition, there should be a slight overlap between the welding beads, and the arc should be started a section ahead of the end of the previous welding bead. Using instantaneous control of the welding power source can compensate for the shallow penetration during arc ignition. When the welding power source starts welding, the welding current will be greater than the actual current used. It is necessary to ensure that the penetration performance is good when the electrode starts burning. A few seconds after starting, the welding current will reduce to the normal value range again. Obtain a smooth appearance; the appearance of the weld should be kept smooth and clean, and uneven welds, arc craters, and pores should be polished.

The second is swing. When the welding current and voltage are constant, the slower the welding speed, the greater the welding heat input. Swinging reduces walking speed and increases heat input. Because the performance of stainless steel plate weldments is prone to deterioration under high heat input, swinging should generally be prevented. But sometimes in order to get a good shape, you still need to use a certain swing gesture, but at this time it should be as small as possible. The swing amplitude of the electrode in manual arc welding should not be greater than 4 times the diameter of the electrode.

The third type is arc extinguishing. When extinguishing the arc, the welding rod is required to make a circular motion above the molten pool, and the welding rod is pulled above the deposited metal to extinguish the arc. If the welding rod is pulled too fast, shrinkage holes or arc craters will form. These arc craters are difficult to remove when re-starting the arc and are weak areas on the weld that are prone to corrosion. Improper arc extinguishing treatment may also cause arc crater cracks. The above methods can ensure that the closing arc crater is small, easy to refuse, and no crater cracks are formed. For submerged arc automatic welding, an arc extinguishing plate must be added to the end of the joint.

The fourth is penetration, because the alloy content of stainless steel plates is usually relatively high, and the root penetration is much shallower than ordinary carbon steel. This interaction with the high shrinkage stress during welding will cause the root gap to shrink. This requires the joint assembly size to be increased and the positioning weld spacing to be narrower.