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HAZ hardening

The unwanted hardness increase in the heat-affected zone through rapid cooling and martensite formation.

HAZ hardening is the unwanted hardness increase in the heat-affected zone (HAZ) next to the weld. The arc heats the base metal to austenitising temperature and the cold plate quenches it — hard, brittle martensite forms. Hardening is the main cause of cold cracks. It depends on carbon content and cooling rate. Countermeasures: preheating, limited heat input, post-weld treatment.

WEZMartensitKaltriss

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