Atmospheric Hydrogen Behavior in SCM435 Steel Associated with Hydrogen Embrittlement

Abstract

  It is widely known that atmospheric hydrogen induces delayed fracture of high-strength steels. However, the atmospheric hydrogen behavior associated with hydrogen embrittlement has not been fully understood. In this study, using deuterium as a tracer of atmospheric hydrogen, the hydrogen behavior during deformation and fracture of SCM435 steels was studied by means of the tensile testing apparatus equipped with a quadrupole mass spectrometer installed under an ultrahigh vacuum chamber. As a result, it was revealed that the atmospheric hydrogen atoms were highly released at the beginning of plastic deformation. It was also shown that atomic hydrogen as well as molecular hydrogen was evolved at the moment of brittle fracture.