What are the technical measures to avoid welding blowholes?

The porosity produced by weld metal can be divided into internal porosity, surface porosity and joint porosity.

Internal pores: There are two shapes. One is that spherical pores are mostly produced in the middle of weld. Reason:

1, welding current is too large;

2. The arc is too long;

3, the speed of transporting the stick is too fast;

4. The welding parts are not clean;

5. covered electrode is wet.

6. The welding environment temperature is too low.

The above-mentioned causes of blowholes can be solved by proper adjustment and attention to welding technology and operation methods.

Surface porosity: the causes and solutions of surface porosity;

1, the welding part is not clean, and it is easy to produce air holes. Therefore, it is necessary to remove oil, rust and other dirt before welding. When low hydrogen covered electrode welding is used, the requirements are more stringent.

2. The welding current is too large. It makes the coating in the second half of covered electrode turn red, and it is easy to produce pores. Therefore, it is necessary to adopt appropriate welding specifications. It is suggested that the tail of covered electrode should not be red under the maximum welding current.

3. Low-hydrogen coated covered electrode is easy to absorb moisture, so it should be baked at 350℃ for about 65438 0 hours before use. Otherwise, air holes are easy to appear.

Joint blowhole: When using low hydrogen covered electrode, surface and internal blowholes often appear at the weld. Solution: when welding the joint, the arc should be struck at a distance of 9 ~ 10 mm from the arc pit. After arc burning, the covered electrode should be transported in the opposite direction, and returned to the arc pit for full melting, and then moved forward, or this type of blowhole can be avoided by arcing at the weld.