Maksimov S. Physical-metallurgical peculiarities and technology of arc welding of low alloyed steels in water

The thesis is devoted to studying of features of influence of the water environment on physical-metallurgical mechanism of the arc welding process and development on this basis of the theoretical fundamentals and scientifically proved complex of the metallurgical and technological measures of maintenance of quality of the low-carbon and low-alloyed steels welded joints with strength up to 600 MPa. Conditions of the stable arc burning in the water environment are certain at the increased pressure. Idea about the mechanism of the porosity formation of a hydrogen origin is developed and laws of influence of the welding conditions on density of the weld metal are evolved. Methods of control by structure and properties of the weld metal executed under water, and their alloying principles for welding steels, inclined to cold cracks formation in HAZ, are established. Qualitative and quantitative influence of the structural and hydrogen factors which define the increased susceptibility of welded joints to underbead cracks in extreme conditions of underwater welding is studied. The complex of the metallurgical and technological methods of ensuring of the welded joints quality of the low-alloyed higher strength steels, principles of creation of the electrode materials of new generation and examples of their realization is developed.