900～600℃温度域における鋼の脆化特性

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抄録

The embrittlement of carbon steels in the temperature range from 900 to 600°C was studied by the hotstage tensile test as well as fractographic analyses, and the mechanism of formation of transverse facial cracks in the continuously cast steels was discussed in terms of this embrittlement. Factors affecting the embritlement are the austenite grain size, the precipitates such as sulfide and oxide and the film-like proeutectoid ferrite formed along the austenite grain boundary. Thus, lowering the impurity content, refinement of the austenite grain and also slower rate of cooling are effective to minimize this embrittlement. However, the best way to have sound slabs is to avoid this poor ductility temperature region at the benching point.