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Tempered microstructure

The structural state obtained after reheating quenched steel under controlled conditions. The relief of internal stresses and precipitation of fine carbides increases ductility and toughness.

You temper after hardening to give the steel toughness back and relieve the stresses. The structure softens, hardness drops in a controlled way. When welding hardened parts, this is a critical point: if you don't control the heat, the structure can change unintentionally and you get cracks. Keep heat input low and let the part cool slowly, then the structure stays stable. If unsure, anneal the part before welding and re-harden it afterwards.

MetallurgieSchweißtechnik

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