Journal of Welding Science

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In this investigation, the effect of heat input of SMAW process on the microstructure and mechanical properties of Hadfield steel weld joints was investigated. For this purpose, 4 annealed sheets with thickness
2 mm prepared from Hadfield steel and then welding applied by SMAW process with 6.75 and 11.25 kJ/mm heat input values. The evaluation of the microstructures of welding joints was conducted by optical microscopy and the joints mechanical properties were examined by tensile, charpy impact and microhardness measuring tests. The results indicated that by increasing the heat input in the SMAW process, microstructure consisted from smaller grains, and strength and microhardness increased but impact energy was reduced.  

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In the present study, effect of Ni alloying element on the characteristics of deposited weld metal of E7018-G electrode was evaluated. Therefore, electrodes contained different amounts of Ni (0-1.7wt.%) were designed, manufactured and welded via SMAW process. Microstructural studies revealed dichotomy effect of Ni on the deposited weld metal microstructure, i.e. increasing the Ni content up to 1.2wt.% improved the formation of acicular ferrite in the weld metal microstructure and caused significant grain refinement at the reheated zone of weld metal. While, higher Ni content (>1.2wt.%) resulted in some raising in the widmannstatten ferrite content in the weld metal. Strength multiplied by impact energy parameter (UTS×CVN) was used for mechanical properties assessment. Mechanical properties evaluation revealed the highest UTS×CVN parameter achieved in the weld metal contained 1.2wt.% Ni. Hardness of the weld metal increased with increasing Ni content which is related to the formation of micro constituents in the microstructure of weld metal and increasing their content with increasing Ni content.