Protsenko P. Increasing Cold Resistance of Welded Joints of Thermally Hardened Silicon-Manganese Steels.

The thesis is focused on the provision of serviceability of welded joints in structures of low-alloyed silicon-manganese thermally hardened steels at subzero temperatures (up to -70 ?C). It develops the concept of mechanism of alloying elements influence on the weld metal structure and properties, arc stability, and electrode metal transfer characteristics. Optimum compositions of alloyed electrode wires Св-08ХГ2СНМТ and Св-08ХГНМТ that provide the required strength and high impact toughness of the weld metal at temperatures up to -70 ?C have been developed and their performance characteristics have been studied. Peculiarities of formation of the structure and properties of the HAZ metal in conditions of the welding thermal cycle have been investigated, resistance of the HAZ metal to cold cracking has been assessed, and the impact of weld heating on cold resistance of the HAZ metal has been determined. New technological capabilities of the pulsed twin-arc welding process have been revealed. The developed points of primary and generalized technological recommendations have been tested at a number of industrial enterprises fabricating responsible metal structures of cold resistant low-alloyed high-strength steels.