Influence of phosphorus on weld heat affected zone toughness in niobium microalloyed steels

Author: Faulkner R. G.  

Publisher: Maney Publishing

ISSN: 1743-2847

Source: Materials Science and Technology, Vol.5, Iss.11, 1989-11, pp. : 1095-1101

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Abstract

Weld heat affected zone microstructures have been simulated in a niobium microalloyed C–Mn steel. These structures have been Charpy impact tested and examined metallographically. Troughs were observed in the plots of Charpy energy against post-weld heat treatment time at 600°C. The explanation for this behaviour is shown to be associated with non-equilibrium segregation of phosphorus to lath boundaries in the steel. Mathematical modelling of non-equilibrium segregation, together with high spatial resolution analytical electron microscopy results, support this contention. Using the predictions of the model, several suggestions are made concerning the alleviation of phosphorus segregation to boundaries and hence the reduction of cracking susceptibility during post-weld heat treatment of the steel.MST/994