Electron Beam Welding of High Strength Quenched and Tempered Steel

摘要

The paper deals with the investigation of microstructure and mechanical properties of electron beam welded joints of high strength steel grades S690QL and S960QL in quenched and tempered condition. The microstructure of base metal was composed of bainite and martensite mixture at hardness about 270HV10 and 340HV10 for the S690QL and S960QL steels, respectively. The weldment was composed of several characteristic subzones revealed on the transverse sections. The central region of the weldment consisted mainly of coarse columnar dendritic grains which perpendicular to the fusion zone boundary. The microstructure of the heat affected zone near the fusion line consisted mainly of martensite, however, in both steels the microstructure varied with the distance from the fusion line. The tensile strengths of welded joints were R_m=850 MPa (S690QL) and 1074MPa (S960QL) and corresponded the tensile strengths of the base materials.