Acicular ferrite in carbon-manganese weld metals: An overview

Acicular ferrite has been identified as the microstructural feature which controls the strength and toughness of carbon manganese weld metals. The present overview seeks to summarize the existing understanding of the nature of this phase and the control through changes in matrix hardenability, cooling rate in the temperature range 800 to 500° C, and the presence of suitable non-metallic nuclei. It also highlights those areas where further research may be required to complete our understanding.