Vysokoteplotní provozní zkřehnutí RAFM oceli Eurofer97

High-temperature long-service embrittlement of the R.A.F.M. EUROFER97 steel

abstract

en

The ferritic-martensitic reduced activation steel Eurofer97 is candidate structural material for in-vessel components of proposed fusion reactors. The embrittlement of the high-chromium ferritic-martensitic steels implies important limitation for use of these materials. The microstructure and fracture properties of the Eurofer97 steel sheets of thickness 25 mm were investigated in as-received state and in state after long-time thermal ageing (550 C/5.000 h/air). Detailed microstructure studies were carried out by means of optical, electron and quantitative electron microscopy in as-received state and in state after long-time thermal ageing. Mechanical properties were evaluated in both states by means of Charpy impact testing. The microstructure of the Eurofer97 consisted of tempered martensite with M23C6 and MX precipitates. The isothermal ageing caused evident shift in tDBTT about +5 C, no proofs of embrittlement were observed on fracture surfaces

Feriticko-martenzitická oceli se sníženou aktivací Eurofer97 je kandidátní konstrukční materiál pro jádrové komponenty navrhovaných fúzních rekatorů. Zkřehnutí vysoce chromových ocelí vyvolává významné omzenení použití těchto materiálů. Mikrostrukturní a lomové vlastnosti 25 mm plechu z Euroferu97 byly zkoumány v dodaném stavu a stavu po dlouhodobém žíhání (550 C/5.000h/vzduch). Detailní mikrostrukurní studie byly provedeny prostředky světelné, elektronové a kvantitativní elektronové mikroskopie v dodaném a žíhaném stavu. Mechanické vlastnosti byly také hodnoceny v obou stavech prostřednictvím zkoušky rázem v ohybu. Mikrostruktura je tvořena popuštěným martenzitem s karbidy typu M23C6 a MX. Dlouhodobé žíhání způsobilo posun tDBTT o asi +5C, přičemž nebyly na lomových plochách nalezeny stopy zkřehnutí.

The ferritic-martensitic reduced activation steel Eurofer97 is candidate structural material for in-vessel components of proposed fusion reactors. The embrittlement of the high-chromium ferritic-martensitic steels implies important limitation for use of these materials. The microstructure and fracture properties of the Eurofer97 steel sheets of thickness 25 mm were investigated in as-received state and in state after long-time thermal ageing (550 C/5.000 h/air). Detailed microstructure studies were carried out by means of optical, electron and quantitative electron microscopy in as-received state and in state after long-time thermal ageing. Mechanical properties were evaluated in both states by means of Charpy impact testing. The microstructure of the Eurofer97 consisted of tempered martensite with M23C6 and MX precipitates. The isothermal ageing caused evident shift in tDBTT about +5 C, no proofs of embrittlement were observed on fracture surfaces

Eurofer97, zkřehnutí, rázové chování

Eurofer97, embrittelement, impact behaviour

14.11.2009

The indian Institute of Metals

Kolkata (Indie)

152–152

1