Nanostructures in welded joints and their interconnection with operation properties

Abstract

The role of structural factors in ensuring optimal properties of materials and their operational reliability has been shown. Studying the phase composition and nanostructures in the welded joints (heat-affected zone, weld metal) of high-strength structural steel produced by advanced high-speed technologies hybrid laser-arc welding. Structural parameters (dimension of grains and subgrains, dislocation density, nanoparticles) and phase changes in the welded joints were studied by using of analytical scanning electron microscopy, optical metallography, and for fine study the transmission electron microscopy was used as well. The most influential structural factors are the dispersing of martensite structure and bainite substructure, equable distribution of particles of structural phases and the absence of extended dislocation clusters—zones of crack incipience and propagation. Such substructure of welding joints of high-strength structural steel produced by laser-arc welding provides the high complex of strength properties and crack resistance.