The morphology of acicular ferrite in alloy-steel weld metals has been investigated. The effect of the prior austenite grain size on acicular ferrite formation has also been studied. It is found that acicular ferrite can form in reheated weld metals when the austenite grain size is relatively large. On the other hand, classicla sheaf-like bainite will form at the same temperature if the austenite grain size is kept small. Further results strongly suggest that acicular ferrite is in fact intragranular bainite rather than intragranular Widmanstatten ferrite.
Journal of Materials Science, Vol. 26, 1991, 839-845.Bainite