Novice welding is prone to pimples at the beginning, what is this?
During welding, the temperature of the weldment before it is welded is lower, which makes the penetration depth of the starting section shallow. When we start the arc, the weldment does not heat up quickly, resulting in uneven heat transfer to the weld area. In this way, the first molten droplet cannot be uniformly transitioned into the molten pool for reaction, which is easy to cause the phenomenon of discontinuous and uneven molten droplets.
Secondly, within 2 seconds of the electrode being arc starting, the coating has not yet formed a large amount of shielding gas. This means that the first melted droplets are not adequately protected and are susceptible to oxygen and water vapor in the air. These factors can cause the surface of the molten droplet to oxidize, making it unstable and difficult to adhere evenly to the weld.
The long arc preheating method is a method used to avoid the formation of bumps during the start of welding. The specific operation steps are as follows: arc starting: starting the arc at a distance of 1-2 cm from the starting point, then elongating the arc, using the skipping arc welding method, swinging back and forth at the starting point position and the starting position, and preheating the weldment.
Lower the arc: When the temperature of the weldment reaches a certain level, the arc is lowered and transferred from the starting point to normal welding.
During the whole process, it is necessary to pay attention to the fact that the arc cannot be extinguished, and at the same time, the preheating time and arc height should be appropriately adjusted according to the thickness and material of the weldment.
The long-arc preheating method can effectively avoid the formation of pimples during the initial welding. In addition to the long arc preheating method, there are the following methods to avoid the formation of pimples during the initial welding: Maintain the appropriate welding speed: The appropriate welding speed allows the molten metal in the molten pool to have enough time for sufficient metallurgical reactions and avoids the formation of lumps due to excessive cooling.
Choose the right electrode: Choosing a electrode with good metallurgical properties and stable arc can reduce spatter and pimple formation during arc starting.
Use the arc striking plate: install an arc striking plate at the beginning of the weld, and start welding from the arc striking plate, which can make the welding at the beginning of the weld more uniform, so as to avoid the formation of pimples.
These methods can effectively avoid the formation of pimples during the beginning of welding, thereby improving the quality and efficiency of welding. However, it should be noted that different welding methods and materials may require different operating techniques, so in practical applications, it is necessary to choose the appropriate method according to the specific situation.