Efeito do teor de molibdênio na microestrutura de juntas soldadas em ligas FE-9CR-5MO

Abstract

Use of ferritic steels grows up with technological advance. Among this steels stands out 9Cr-1Mo steel. With addition of alloy elements has been reach steels with bigger resistance and better weldability. The main of goal of this work is study effect of molybdenum content on microstructural changes, mechanical properties and weldability in a novel alloy 9Cr-5Mo. Was plot diagrams with elements presents to identify phases. A sample of solubilized alloy was taking to characterization by optical microscopy and scanning electron microscopy. The properties of alloy were determined by mechanical tests. Samples were welding without and with material addition by TIG and MIG process respectively. Analysis was made of grain size in HAZ’s alloy, microstructural characterization on weld regions and microhardness. The results obtained showed that the alloy 9Cr-5Mo presents a grain ferritic microstructure large and superior mechanical properties of 9Cr-1Mo to alloy the molybdenum content of favored to a fragile behavior at room temperature, however above 60°C, the alloy show a brittle behavior. In addition to ferritic microstructure, this alloy present carbides formation and martensite after welding. The martensite no undermined weldability.