Cracking Causes of N08800 Fe-Ni Base Alloy Welded Pipe During Bend Forming

The cracking problem of N08800 Fe-Ni alloy welded pipe were found in the actual bend froming process sometimes. The cracking causes in the bend forming process of welded pipe were analyzed by means of macroscopic observation, chemical composition analysis, mechanical property test, metallographic examination and microscopic analysis. The results show that the cracking of N08800 Fe-Ni base alloy welded pipe were all located in the weld. The weld slags and welding shrinkage cavities during welding were the main reasons for the weld cracking during forming. The larger welding slags formed pits under the action of external force and further development caused cracking.