Prediction of Mechanical Properties in Submerged Arc Weld Metal of C–Mn Steel

Abstract

The prediction model has been developed for steel weld metal mechanical properties as a function of flux ingredients such as CaO, MgO, CaF₂ and Al₂O₃ in submerged arc welding carried out at fixed welding parameters. The results of quantitative measurements of mechanical properties on eighteen weld metal samples were utilized for developing the prediction equations of mechanical properties applying statistical design of experiment for mixtures. Among the flux ingredients, MgO appears to be important on its own in influencing the mechanical properties. The other ingredient CaO appears to be most important as it interacts with CaF₂ and Al₂O₃ in influencing weld metal mechanical properties. The prediction equations have been checked for adequacy by performing tests on submerged arc welds using randomly designed flux and found satisfactory. The ISO-response curves were developed for weld metal impact toughness to show the output levels at different percentage of flux ingredients.

Keywords:

• Acicular ferrite
• Binary antagonism
• Binary synergism
• Carbon equivalent
• Extreme vertices design
• Flux ingredients
• Oxygen content
• Prediction model
• Statistical experiments

Notes

Other additions to eighteen nos. of flux samples Wt% SiO₂ = 10.0 Wt%; Fe-Mn = 4.0 Wt%; Bentonite = 2.0; Wt% Fe-Si = 3.0 Wt%; Ni-Powder = 1.0.

∗GBF = Grain Boundary Ferrite; SPF = Side Plate Ferrite; PF = Polygonal Ferrite; AF = Acicular Ferrite; FAS = Ferrite with aligned second phase (Upper bainite).

∗YS = Yield strength; UTS = Ultimate tensile strength.

∗Microstructural constituents: GBF = Grain Boundary Ferrite; SPF = Side Plate Ferrite; PF = Polygonal Ferrite; AF = Acicular Ferrite; FAS = Ferrite with Aligned Second Phase (Upper Bainite).

∗Carbon equivalent (CE)=wt% C.

N.B.: Other additions to eight nos. of flux samples: Fe-Mn = 4.0 wt%, Fe-Si = 3.0 wt%, Ni-Powder = 1.0 wt%, Bentonite = 2.0 wt%.