Type of covering
Diameter and length (mm)
Common to individual welding processes
Preparation of base metal:
- Rust, oil and soil attached on the base metal may cause blowholes.
Preheat and interpass temperature:
- In order to minimize cracking, control of preheat and interpass temperature is a key technique
Immediate postweld heating:
- Heating the weldment at 300-350oC for 10-30 Minutes. Control the temperature carefully, or the hardness of the weld will be decreased.
Postweld heat treatment:
- Postweld heat treatment(PWHT) at 550-750oC is effective to prevent cld cracking and distortion in service.
- Underlaying is effective to prevent cracking in weld here low-alloy steel having high hardenability is hardfaced or where high-hardness weld metal is deposited on carbon steel.
- In hardfacing, the properties of the weld metal will considerably be affected by welding penetration into the base metal.
- Intermittent and symmetrical welding sequences are effective to minimize welding distortion.