AbstractThe results of an investigation of the orientation relationships between adjacent plates of acicular ferrite are reported in an attempt to elucidate further the mechanism of acicular ferrite formation. Welds were made using the manual metal arc technique and the as deposited microstructure of the high strength steel weld deposits was examined using crystallography and transmission electron microscopy. It was found that clusters of acicular ferrite form in such a way that adjacent plates tend to have a similar orientation in space; the reasons for this are discussed.MST/903