Absorbing moisture of electrode coating easily leads to high diffusible hydrogen of welding seam, resulting in hydrogen embrittlement, porosity, cold crack and other defects.Microwave absorption material Fe3O4 is used to promote the reaction of palmitic acid, and reduce the diffusible hydrogen of weld bead. Electrode is immersed to the light petroleum solution containing palmitic and Fe3O4 particles, then the electrode is put into the microwave oven and become water-resistant . The results of FT-IR and SEM indicate that Fe3O4 absorb the microwave and lead to the reaction of palmitic acid and electrode surface. The electrode become water-resistant after microwave reaction, The best ratio of palmitic acid in the petroleum ether is 15%, and the weld diffusible hydrogen decreases to 74%.

In order to investigate the safety performance of welding structure of 10CrNi3MoV hull steel, with the application of FAD method provided by SINTAP, this paper made safety assessment for 2 joints with the same yield stress under-matching ratio but different weld toughness. Based on tensile test and CTOD test results, assessment was carried out. Several different sizes (2a) of weld central crack were given. Then the crack size tolerance for each joint can be found. Through relative analysis, a few conclusions were gained. As long as the assessment level is selected, FAD shape changed little. Weld toughness influenced weakly on a joint’s resistance to plastic instability, but significantly on its anti-brittle capacity. The higher weld toughness is, the more likely assessment point located within failure assessment curve, i.e. the safety performance is correspondingly better.

Electrodes can absorb moisture easily so that the diffusible hydrogen is quite high in the weld bead. Fe3O4 powder is used to promote the reaction of myristic acid and the electrode surface, and reduce the diffusible hydrogen, because of its excellent microwave absorption property. Electrodes are immersed to the light petroleum solution which contains myristic and Fe3O4 particles, then they are put into the microwave oven and become water-resistant . The results of FT-IR and SEM microscope indicate that Fe3O4 powder absorb microwave and melt myristic acid to form the water-resistant film. The best ratio of myristic acid in the petroleum ether is 18% and the diffusible hydrogen of the deposited metal of microwave treated electrode decreased to 83% of the untreated electrode.