Per: EUGENIO TOLEDO DE CARVALHO (USINAS SIDERURGICAS DE MINAS GERAIS SA), Tadeu Messias Donizete Borba (usiminas), Ailton Ribeiro de Avelar Júnior (usiminas)
Abstract:
USI-LN-700MC is a hot strip HSLA (High Strength and Low Alloy) steel, developed by Usiminas to provide manufacturers of road and agricultural equipment the production of high resistant parts, with excellent weldability characteristics. In this context, the influence of the heat input by GMAW/FCAW processes on the microstructure, hardness and tensile strength of welded joints of USI-LN-700MC steel of 8.00 mm thickness was evaluated. The levels of heat input used enabled the deposition of weld beads in a single pass, ensuring high productivity in the joining process. Although the high heat input used resulted in the formation of softened zones due to microstructural transformation in the heat-affected zone, the drop in resistance resulting from this softening was not sufficient to reach the minimum UTS (Ultimate Tensile Strength) specified for the material, fully satisfying the requirements imposed by the welding standards for structural steels. The results showed that the USI-LN-700MC steel is a good alternative to reduce manufacturing costs, as it allows welding with high productivity, without compromising the strength of the components.