Evaluation of Nickel effect on the fatigue strength of E۷۰۱۸-G weld metal

In this study, the effect of nickel (Ni) on the fatigue strength of deposited weld metal from the E۷۰۱۸-G electrode was evaluated. For this purpose, electrodes with different percentages of Ni were made and welded to st-۳۷ steel using manual arc welding process (SMAW). The microstructure, tensile and fatigue properties of the weld metals deposited from the fabricated electrodes were evaluated. Structural studies revealed that increasing of Ni in the chemical composition of the weld metal up to ۱.۲۲ wt.% increases the area fraction of acicular ferrite and decreases the area fraction of bulk and widmanstattenferrites in the weld metal. Increasing of Ni content of weld metal more than ۱.۲۲ wt.%, reduces the acicular ferrite in the weld metal and to some extent the amount of martensite and widmanstatten ferrite phases increases. Investigations of mechanical propertiesindicated that increasing Ni contents of weld metal increase in the tensile and fatigue strengths.

Keywords:

E۷۰۱۸-G , Microstructure , SMAW , Ferrite , Fatigue.