The significant problem in production of special hull structures is welding of high-strength and ultra-strength steels by a tensile strength of 800 MPa and more. High-strength alloy steels require a specific approach to the manufacture of welded structures in comparison with conventional low-carbon and low-alloy. The fundamental difficulty in this steel's type welding is the tendency to appearance of as cold and hot (crystallization) cracks, in addition to the formation of structural phases reducing the resistance to brittle fracture of weld-metal and HAZ metal. Another significant problem in high-strength steels welding is to obtain mechanical properties of welded joints comparable to the level of the base metal in the absence of welded structures heat treatment. Recently in body structures welding of high-strength steels is carried out using ferrite-perlite or austenitic types electrode metal. The general disadvantages of currently used special equipment welding technologies are the low mechanical characteristics of weld joints. The high-strength steel's weldability problem decision as well as the weld metal and HAZ metal mechanical properties improvement may be achieved by the optimal welding thermal cycles and the faithful determination of welding electrode materials. The present paper describes the main ways of high-strength steel weldability problem resolving, provided by the development of flux-cored wire. Moreover, article indicates the ways to improving the mechanical properties of the weld metal and HAZ. It was offered welding technology, taking into account the above peculiarities of plant's production. Listed measures allow cancel costly heat treatment process and obtain a defect free weld joints. It was established that defects in the form of cracks on the fusion line and in the HAZ during the metallographic examination of microsections were not detected. Developed cored wire with Fe-Cr-Mn-Mo-N doping system, containing up to 0.3 wt. % nitrogen, allows to obtain an austenitic structure in the weld metal with improved mechanical properties.