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Abstract: The effects of alloying elements and temperature on corrosion behavior in supercritical water (SCW) were investigated for oxide dispersion strengthened (ODS) steels to design alloy compositions for corrosion-resistant ODS ferritic steels. Corrosion tests of the ODS steels were carried out at 400, 500, and 600°C under 25MPa with 8ppm of dissolved oxygen. The addition of 4wt.%Al is effective to improve the corrosion resistance of 16Cr-ODS steel, suggesting that an adequate combination between Cr and Al content ranges (14–16)Cr and (3.5–4.5)Al. The addition of Ce or Zr to W-added ODS steel is expected to increase its corrosion resistance. At higher temperatures, the addition of 4wt.%Al to 16Cr-ODS steel induces better corrosion resistance rather than the temperature of 400°C. It is considered that for 16Cr-ODS steels with Al, the continuous alumina mainly suppresses the inward oxygen diffusion and the Fe–Cr spinel adds to the suppression of oxygen diffusion. [Copyright &y& Elsevier]

Abstract: Fracture toughness of blanket structural materials is one of the important material engineering properties to design structural components and evaluate the degradation during reactor operation. The present study showed that the master curve (MC) methodology to evaluate change in fracture toughness in the cleavage regime of a reduced-activation ferritic (RAF) steel before and after a thermal embrittlement treatment was applied by using sub-sized compact tension (CT) specimens. The reference temperature of MC for the JLF-1LN steel was estimated as −52°C by using 1/2CT specimens. The shift of the reference temperature obtained by the MC methodology was judged to be somewhat larger than that of the ductile–brittle transition temperature shift obtained by the Charpy impact tests. [Copyright &y& Elsevier]

Four different sizes of compact tension (CT) specimens of a reduced activation ferritic steel, JLF-1 steel, were fabricated and the fracture toughness was measured at room temperature by means of the unloading compliance method referring to in the ASTM E1820-99a. The JQ values obtained for the 1T–1CT and 1/2T–1CT specimens were 404 and 623 kJ/m2, respectively, indicating that the JQ value increased with decreasing the specimen thickness. On the other hand, the JQ value decreased when specimens were miniaturized while maintaining the similar proportions. The JQ values for the 1/2CT and 1/4CT specimens were 371 and 321 kJ/m2, respectively. Specimen size effects are interpreted in terms of an increase in the plain stress state region and plastic zone size at the crack tip in the specimen. [Copyright &y& Elsevier]

Effects of tensile stress on Cu clustering were explained using atom probe tomography (APT) results of Fe–0.6 wt.%Cu alloy specimens irradiated with 6.4 MeV Fe ions while applying a tensile stress of 60 MPa at room temperature (less than 50 °C) and 290 °C. The hardening under the tensile-stressed irradiation was smaller than that under the stress-free irradiation at both room temperature and 290 °C. APT results showed that well-defined Cu clusters were formed in all specimens even under the room temperature irradiation. The Cu clusters under the tensile-stressed condition were smaller and had higher densities than those under the stress-free condition. The lower Cu content in clusters and more diffuse Cu clustering were obtained for the specimens irradiated under the tensile-stressed condition. The hardening efficiency of Cu clusters was correlated with the Cu content in clusters and the coherency of interface between a cluster and the matrix. Application of tensile stress would control hardening by changing the nature of Cu clusters. [ABSTRACT FROM AUTHOR]

Abstract Currently, advanced ODS copper alloy is under study as a potential fusion material providing good mechanical properties. In this work, in order to develop a high performance ODS copper containing 0.5 wt% Y 2 O 3 oxide particles, the effect of room temperature rolling and subsequent annealing on the grain structure evolution, texture development and tensile properties are studied using EBSD, TEM and tensile tests. Microstructure evolution studies show the grain structure coarsens by enhancing the Brass texture during increase of rolling reduction and a unique single crystal-like brass-texture deformed structure is achieved after 80% rolling reduction. We found the deformation mechanism of partial slip by a 6 〈 211 〉 dislocations facilitated by the pinning of a 2 〈 101 〉 perfect dislocations through fine oxide particles is responsible for formation of Brass texture during room temperature rolling. Furthermore, the recrystallization of ODS copper retards to high temperature of ~700 °C and shows a fine-grained microstructure with different orientations of Goss, Brass, S and Copper. Evaluation of microstructure-mechanical properties of the recrystallized samples expresses that the bimodal grain size distribution at 800 °C for 30 min offers a good tensile strength-duc t ility (UTS: 491 MPa, el t : 19%) at ambient temperature. [ABSTRACT FROM AUTHOR]