On the effect of silicon on toughness in recent high quality hot work steels

Fracture surfaces on H11-type Charpy impact samples were studied as a function of tempering temperature and Si content. The recently discovered effect of Si on toughness after high-temperature tempering was shown to be the result of a more favourable distribution of secondary alloy carbides in low-Si steels.

► Impact tests and fractography to elucidate the effect of Si on toughness.
► Four steels with different Si contents evaluated after heat treatment.
► Coarser alloy carbides cause lower toughness in high Si steels.
► Low Si promotes homogeneous precursor phase for alloy carbides.
► Finer and better-distributed alloy carbides enable higher toughness in low Si steels.