Microstructural and Mechanical Characterization of Electron Beam Welded Joints of High Strength S960QL and Weldox 1300 Steel Grades

Abstract

The paper shows the results of metallographic examination and mechanical properties of electron beam welded joints of quenched and tempered S960QL and Weldox 1300 steel grades. The aim of this study was to examine the feasibility of producing good quality electron beam welded joints without filler material.Metallographic examination revealed that the concentrated electron beam significantly affects the changes of microstructure in the weld and the adjacent heat affected zone (HAZ) in both steel grades. The microstructure of the welded joints is not homogeneous. The four zones, depending on the distance from the weld face, can be distinguished. Basically, the microstructure of the weld consists of a mixture of martensite and bainite. However, the microstructure of HAZ depends on the distance from the fusion line. It is composed of martensite near the fusion line and a mixture of bainite and ferrite in the vicinity of the base material.Significant differences in mechanical properties of the welded joints were observed. For a butt welded joint of the S960QL steel grade the strength is at the level of the strength of the base material (R m = 1074 MPa). During the bending test the required angle of 180° was achieved. The impact strength at -40°C was 71,7 J/cm 2 . In the case of the Weldox 1300 steel grade butt welded joints exhibit high mechanical properties (R m = 1470 MPa), however, the plastic properties are on the lower level than for the base material.Keywords: electron beam welding, high strength quenched and tempered steel, weld microstructure

Changes of microstructure and mechanical properties of the HAZ of the S960MC steel sheet weld joint

“…In the HAZ of the examined weld, the three main sub-zones were identified (naturally, transition areas were present between these clearly distinguished subzones). The similar behaviour was reported by authors [7,13,16,17,12]. In the direction from the weld metal to the base metal, the first observed zone was the coarse grain zone (CGHAZ) (Figure 3e).…”

“…U ZUT-u koji je ispitan u ovom radu su razdvojene tri glavne podzone (uz prelazna područja izmedju njih). Slično ponašanje je već saopštavano [7,13,16,17,12]. U smeru od metala šava prema osnovnom metalu, prva zona koja se može uočiti je grubozrna zona (CGHAZ), slika 3e.…”

Matching effect on fatigue crack growth behaviour of high-strength steels GMA welded joints

“…During the welding process, the elements are affected with heat-effect and mechanical loads, which result in inhomogeneous welded joint [7]. The inhomogeneity of the welded joints appears both in microstructural and in geometrical aspects.…”

Gas Metal Arc Welding of Thermo-Mechanically Controlled Processed S960MC Steel Thin Sheets with Different Welding Parameters

“…The ultra-high strength steels exhibit also high abrasion resistance, when comparing to the carbon steels [1]. These properties are obtained by the combination of alloying by small addition of V, Ti, Cr, Ni, Si, Mn, Mo, and properly chosen processing, which allows to achieve the high strength properties while the amount of C is maintained low [2]. Nowadays, in the many industrial applications, the usage of the high strength steels is increasing [3].…”