Fig. 6: 3D ultra-depth micro-morphology of the welded joints after 30 d immersion.

a–c Show the 3D ultra-depth micro-morphology of BM, HAZ, and WZ zones after 30 d immersion in the medium with 0% organic carbon sources level. d–f Show the 3D ultra-depth micro-morphology of BM, HAZ, and WZ zones after 30 d immersion in the medium with 1% organic carbon sources level. g–i Show the3D ultra-depth micro-morphology of BM, HAZ and WZ zones after 30 d immersion in the medium with 100% organic carbon sources level.