← Glossary

Acicular ferrite

A needle-like ferrite microstructure that preferentially nucleates on microscopic inclusions in weld metal. It significantly improves the low-temperature toughness of welds.

Acicular ferrite is the microstructure you want in the weld if it needs to be tough. To form it, you need fine oxides and sulfides in the weld metal that act as nuclei. Fine ferrite needles grow from them in all directions, the structure becomes fine and interlocked, and cracks don't propagate well in it.

MetallurgieSchweißtechnik

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