Recent work on the resistance of high strength AISI(1) 4130 steel to cracking by hydrogen found that failure occurred intergranularly from hydrogen stress cracking (HSC) when tempered below 500 C.1 Tempering above this temperature produced a transition in fracture mode to transgranular separation. This transition was attributed to phosphorus segregation during austenitizing and subsequent failure from a hydrogen-phosphorus interaction at the prior austenite grain boundaries.1 Segregation of low levels of phosphorus was confirmed by Auger analysis of the grain boundaries. Test specimens tempered at 500 C and above would not fracture intergranularly, so Auger analysis could not be performed. It was therefore assumed that at these higher tempering temperatures, P was no longer concentrated at the boundaries, but this could not be confirmed.
The work presented in this note does not strictly confirm this earlier assumption, but it describes the distribution of P as a function of...
