Hydrogen induced cracking in cold worked AISI 4140 steel welds

Abstract

The relative susceptibility to hydrogen induced cracking of cold deformed AISI 4140 steel welds was investigated. Controlled amounts of diffusible hydrogen were introduced into these weldments by utilizing the gas metal arc welding process with additions of hydrogen to the shielding gas. The crack behaviour was measured in terms of total crack length and distance from the fusion line. The crack propagated along the coarse grain structure of the HAZ about the fusion line. The refinement of the grain resulting from the increased cold roll reduces the crack activity. The susceptibility to hydrogen induced cracking of the cold worked samples appear to be sensitive to a critical value of residual stresses and to the orientation of the weld with respect to the rolling direction.