Mikhoduj O. Effect of technological factors on the formation of residual stresses in high-strength steel welded joints

The mode of distribution of residual stresses in welded joints made from low-carbon alloyed martensitic-bainitic steels with a yield strength ( 600 MPa is studied. Aim of work: to establish optimum technological parameters of arc welding high-strength alloyed steels, providing the reduction of residual stresses in welded joints on the basis of investigation of proceeding the phase, structural transformations and thermodeformational processes in them. Methods of investigations: holographic, mathematical, optic metallography, dilatometric mechanical, chemical and spectral analysis. Ways of decreasing residual stresses in welding high-strength steels are defined. Methods of realization of processes, at which the minimum level of residual stresses is provided, are developed. The effect of thermophysical processes and structural transformations on the regularities of formation of residual stresses in welded joins is investigated. An experimental-design aproach has been developed which makes it po ssible to predict the nature of proceeding temperature deformations in weld metal and HAZ. The effect of structure of weld metal on the formation of residual stresses is considered. the effect of parameters of welding conditions and temperatures of preheating on the formations of residual stresses is studied. Main statements of technological processes which provide a minimum level of residual stresses in high-strength steel welded joints are worked out. The main statatements of the processes developed are implemented at the metallurgical works of JSC "Uralmash" in repair welding of thick castings of components of high-strength steels.