Effects of hydrogen on the fracture toughness of 42CrMo4 steel quenched and tempered at different temperatures

摘要

The aim of this paper is to study the effect of hydrogen on the fracture toughness of 42CrMo4 steel quenched and tempered at 500, 550, 600, 650 and 700 degrees C. The influence of hydrogen was assessed by means of fracture toughness tests carried out on compact CT specimens, pre-charged with gaseous hydrogen in a pressurized reactor at 19.5 MPa and 450 degrees C for 21 h. Thermal desorption analysis (TDA) and finite element simulations (FEM) were employed to study the hydrogen diffusivity and solubility of the different steel grades. Additionally, X-ray diffraction (XRD) was used to determine the dislocation densities present in these steel microstructures and scanning electron microscopy (SEM) to analyse them and to identify the fracture micromechanisms that took place during the fracture toughness tests.