Fragilização por hidrogénio no aço ABNT 10B22 modificado carbonitretado temperado e revenido a 400 °C

The hydrogen embrittlement is a problem that affects metallic structures causing a decrease in mechanical properties of materials, mainly by increasing brittleness and reducing toughness and strength. In the case of applications such as high strength bolts, which have suffered surface hardening treatment the hydrogen can be introduced into the material during the manufacturing process, particularly by steps of wet surface treatment methods. In this work was studied the permeation of hydrogen effects with different charging levels on samples of modified ABNT 10B22 steel. The samples were submitted to carbonitriding treatment, and then were quenched and tempered at 400 °C. The specimens were subjected to the forced introduction of hydrogen through galvanostatic control in three levels of charging, and then pulled using the slow strain rate technique. The samples were morphologically characterized by scanning electron microscopy. Furthermore, it was determined the samples hardness profile. It was observed that, as the intensity of the hydrogen charging current increase, there is a reduction of mechanical properties of material, such as reduction of toughness, ultimate tensile strength (UTS) and ductility.