Coarse Grain Formation in HAZ

Local microstructural coarsening in the near-fusion line of the heat-affected zone caused by excessive peak temperatures. This results in a significant local reduction in toughness and ductility.

If you heat the metal in the HAZ too much, you get coarse grains. The grains then grow together unevenly, the structure becomes coarse, and the material loses toughness and becomes brittle. The part can then crack or break faster in service. So be careful not to put in too much heat and let the cooling run too slowly. With higher-strength or carbon-rich steels, you have to be especially careful. Keep the heat input as low as possible and don't let the part glow unnecessarily.

MetallurgieSchweißtechnik