welding process points:
(1) Correct selection of welding consumables
(2) Joint type: joint type with large groove angle and small pure edge
(3) Cleaning near the groove and welding wire: The characteristics are important to prevent hot cracks and blowholes.
(4) Preheating before welding: Normally no preheating is required before welding. The temperature between layers should be controlled below 100 °C. However, when the temperature of the base metal is lower than 15°C, it should be heated to 15-20°C to avoid moisture condensation.
(5) Welding process:
◇ Limit the heat input, use a small amount of wire and maintain the stability of the arc voltage, and use a short arc non-oscillating or small swing operation method.
强制 For small diameter pipe welding, forced cooling measures should be taken to reduce the high-temperature residence time of the weld and increase the cooling rate of the weld.
After welding, the slag and spatter on the surface of the weld should be promptly cleaned to prevent embrittlement or corrosion degradation of the weld due to impurities such as S in the slag.
(6) Post-weld heat treatment: Post-weld heat treatment is generally not recommended. However, heat treatment is sometimes required to ensure that no intergranular corrosion or stress corrosion occurs during use.