Abstract
The effect on strength properties, microstructure and HIC of heat treatment of normalizing rolling, normalizing and quenching & tempering was analysed. The following conclusions can be drawn: The strengths of samples of normalizing rolling and normalizing range 459MPa~470MPa. However the strengths of quenching and tempering samples range 539MPa~614MPa. And the strengths of quenching and tempering samples decrease with the tempering temperature rising. The Max. CLR is around 14% of normalizing rolling samples but 4% of normalizing samples. However no cracks was observed on the quenching and tempering samples. The cracks originate on center of samples’ thickness direction and propagate along pearlite bands. However the HICs have a low occurrence rates on the quarter of samples without origination that only exist on thickness center of samples. The quenching and tempering microstructure can prevent the propagation of the originated HIC, which improves the HIC resistance properties of vessel steel.
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