Role of structural-phase condition in change of service properties of welded joints from complexly alloyed alloys

Aim. Relevance of complex experimental-analytical estimation of relationship of structure and properties of welded joints for welding mode optimizing was shown by example of analysis of structural-phase changes of welded joints of complexly alloyed aluminum-lithium and heat-resistant titanium alloys. Procedure. The objects of examination in presented work were welded joint of complexly alloyed Al-Li alloys 1460, produced by non-consumable argon-arc welding using Sv1201 and Sv1201+0.5%Sc fillers as well as friction stir welding without filler, and welded joint (electron-beam welding) of pilot heat-resistant multi-component titanium alloys, which refer to pseudo - a and a +p titanium alloys. Experimental information on structure-phase condition of metal of welded joints was received by light, analytic scanning as well as microdiffraction transmission electron microscopy. Results. Estimations of particular input of specific type of structures in change of main service properties (strength, ductility, crack resistance) joints were carried considering structural-phase condition (chemical composition, distribution and sizes of phase, grain, sub-grain and dislocation structures), forming in welded joint at different investigated welding conditions and external loading. Effect of examined structural condition on character of distribution, level of increasing internal stresses and mechanisms of their relaxation was also determined. Scientific novelty. Experimental-analytical estimations presented in the work can be qualified as solution of important scientific-technical task in area of materials science, which lies in providing of welded joint quality. Practical importance. Proposed are analytical estimations, which allow for determining input of separate structural constituents in the indices of service properties of welded joints and predicting increase of strength characteristics and crack-resistance.