Comparison of the advantages and disadvantages of the forward and backward welding methods

Ⅰ. Forward welding

Forward welding is a welding method that pushes the welding head forward from the starting position of the material. It has the following advantages:

1. Fast welding speed: Since the welding head is always moving forward, the forward welding speed is faster, which can improve production efficiency.

2. Small welding deformation: The heat input of forward welding is small, so it can reduce the thermal deformation of the metal and make the deformation smaller.

3. Gas protection can be achieved: During welding, protective gas can be provided in the welding area, which can effectively reduce the generation of pores and other defects.

However, forward welding also has the following disadvantages:

1. It is easy to generate pores: Since the welding head is always moving forward, the gas generated during welding is not discharged in time, which is easy to cause pores.

2. It is easy to generate inclusions: The direction of the welding head moving forward is opposite to the direction of the molten pool flow, which is easy to bring impurities into the weld and cause inclusions.

Ⅱ. Retreat welding

Retreat welding is a welding method that pushes the welding head backward from the starting position of the welded metal. It has the following advantages:

1. High welding quality: The heat input of the backward welding method is large, so the welding quality is relatively good and there are fewer welding defects.

2. Easy to control welding quality: Since the welding head is willing to move backward from the welded metal during welding, welding defects can be discovered and repaired in time.

3. Inclusions can be effectively controlled: The welding direction of the backward welding method is consistent with the flow direction of the molten pool, and it is not easy to bring in impurities, so the backward welding method can effectively control the generation of inclusions.

However, the backward welding method also has the following disadvantages:

1. Slow welding speed: Since the welding head needs to repeatedly return to the starting position, the production efficiency is low.

2. It is easy to produce metal expansion: The heat input of the backward welding method is large, which is easy to produce metal expansion and structural changes.

Conclusion:

By comparison, it can be found that the forward welding method is suitable for occasions with high production efficiency requirements, small weld thickness, but low quality requirements; the backward welding method is suitable for occasions with high welding quality requirements, large weld thickness, but low production efficiency requirements. In actual production work, the welding method should be selected according to the specific circumstances.