ECN publicatie:
Metallographic characterisation of EUROFER97 plate and bar materials
Gepubliceerd door: Publicatie datum:
ECN Environment & Energy Engineering 1-10-2000
ECN publicatienummer: Publicatie type:
ECN-C--00-108 ECN rapport
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Three heats of modified 9%Cr-steels of the EUROFER97 program wereinvestigated. The samples were taken from three plates: 8, 14 and 25 mm thick, and one bar, 100 mm diameter. All three planes of the plates and the bar were investigated by optical and electron microscopy (SEM- EDX) and hardness measurements were made over the cross sections. All samples show a fine homogeneous tempered martensitic microstructure with a prior austenite. grain size of ASTM 10.0-10.3. No elongated austenite grains were found. The microstructure is free of delta-ferrite and segregation bands of carbides. However, some segregation was found in bands of Ti-rich particles and inclusions (sulphides and oxides). To a lesser extent, concentrations of Ta-rich phases were also found. Ta appears to precipitate as relatively large particles, with respect to carbides present. The hardness shows an even distribution over the cross sections, without evident hardness decrease at the plate surfaces. The plate materials show hardness values of about 212HV30. The bar material has a somewhat higher hardness, with an average of 220HV30. No significant variation in hardness with orientation was observed. 3 refs.

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