Efeito da energia de soldagem sobre a zona termicamente afetada de um aço avançado de alta resistência mecânica

Abstract

Advanced High Strength Steels (AHSS) are an attractive alternative in structural applications. Due to the low content of carbon and alloying elements, AHSS steels have good levels of toughness and mechanical strength, in addition to good weldability, however, it is possible to manufacture lighter structural components, thus allowing fuel savings, resulting in a reduction in the emission of carbon dioxide expelled into the atmosphere, becoming an environmentally correct building material. The good combination of mechanical properties allows steel to be widely used in the automotive industry. For such applications, the welding process is inevitable, which produces localized microstructural changes and reduced levels of mechanical strength, in addition to undesirable defects, which generate potential safety and reliability problems. In this work, the influence of the electric arc welding process with shielding gaseous atmosphere (GMAW) in the heat-affected zone was studied, changing the microstructure and mechanical properties of steel DIN EN 10149-2 S700 MC, applying three different welding energies. For this, the specimens after welding were studied through microstructural and macrostructural analyses, tensile, bending and microhardness tests. The results showed that there was a decrease in the tensile strength after welding, due to the phase transformation caused by the heating of the grain growth region, or the thermally affected zone. The samples welded with higher energy showed defects, such as: lack of fusion and porosity, which compromises the integrity of the structure. [resumo fornecido pelo autor]