Abstract:The thermal stability and mechanical properties of China low activation martensitic steel with Zr and Y were investigated via thermal aging at 550 °C for 8000 h. The Laves phase content monotonically increased with thermal aging, and the volume fraction of the Laves phases stabilized in the alloy after 3000 h of thermal aging. The observed degradation in mechanical properties was because of the coarsening of M 23 C 6 carbides and matrix grains during the earlier stages of thermal aging. The precipitation of La… Show more
“…f V is another important parameter of inclusions, and Figure 5 shows the f V of WM inclusions as a function of TiO 2 content. f V , the percentage of inclusion volume in the total volume, can be calculated by Equation (1) [37], in which the spatial number of inclusions per unit volume ( N V ) and the three-dimensional arithmetic average diameter ( d V ) can be obtained by Equations (2) and (3), where d A i is the equivalent section diameter of the inclusion [38]. Figure 5 Volume fraction of inclusions in different WMs as a function of TiO 2 content.…”
EH36 shipbuilding steel has been submerged arc welded under 6 kJ mm −1 heat input employing CaF 2 -TiO 2 fluxes. Ensuing weld metals have been examined with an emphasis on inclusion characteristics. Compositional-wise, the inclusion ensemble is largely categorised as a complex Ti-containing type. It is demonstrated that, as a function of TiO 2 content, the average Ti content in the inclusions is gradually enhanced, which is compensated by the simultaneous reduction of Al and Mn. Meanwhile, inclusion size distribution curves show log-normal patterns with the frequency peaks ranging from 0.3 to 0.4 μm. Furthermore, inclusion number density and volume fraction show a definitive increasing trend, which are concurrent to the O uptake from 110 to 210 ppm enabled by TiO 2 decomposition.
“…f V is another important parameter of inclusions, and Figure 5 shows the f V of WM inclusions as a function of TiO 2 content. f V , the percentage of inclusion volume in the total volume, can be calculated by Equation (1) [37], in which the spatial number of inclusions per unit volume ( N V ) and the three-dimensional arithmetic average diameter ( d V ) can be obtained by Equations (2) and (3), where d A i is the equivalent section diameter of the inclusion [38]. Figure 5 Volume fraction of inclusions in different WMs as a function of TiO 2 content.…”
EH36 shipbuilding steel has been submerged arc welded under 6 kJ mm −1 heat input employing CaF 2 -TiO 2 fluxes. Ensuing weld metals have been examined with an emphasis on inclusion characteristics. Compositional-wise, the inclusion ensemble is largely categorised as a complex Ti-containing type. It is demonstrated that, as a function of TiO 2 content, the average Ti content in the inclusions is gradually enhanced, which is compensated by the simultaneous reduction of Al and Mn. Meanwhile, inclusion size distribution curves show log-normal patterns with the frequency peaks ranging from 0.3 to 0.4 μm. Furthermore, inclusion number density and volume fraction show a definitive increasing trend, which are concurrent to the O uptake from 110 to 210 ppm enabled by TiO 2 decomposition.
“…[ 6,7 ] Ti and Zr elements could also form TiC, (Ti, W) C, (Ti, Ta) C, and V 3 Zr 3 C, which have strengthening effects similar to that of MX with Ta/V, to improve the high‐temperature mechanical properties of steel alloys. [ 8,9 ] Ti and Zr are important alloying elements often used to prepare ODS steel. ODS RAFM alloys are commonly manufactured via powder metallurgy (PM), which involves mechanical alloying, hot powder consolidation (e.g., hot isostatic pressure, hot extrusion, or sparking‐plasma sintering), and heat treatment.…”
Owing to their excellent resistance to irradiation, good creep property, and extraordinary structural and chemical stability in harsh, high-temperature environments, oxide dispersionstrengthened (ODS) reduced activation ferritic martensitic (RAFM) steels are considered prime candidates for advanced structures, including nuclear fusion reactors. [1,2] The excellent properties of ODS RAFM steel can be attributed to the fine grain size of the steel and the dispersed nano strengthening phases, such as Y 2 O 3 , MX (M ¼ Ta, V, X ¼ C, N), and M 23 C 6 (M ¼ Fe, Cr). [3,4] Dispersed Y 2 O 3 particles can not only effectively block dislocation movements but also absorb the vacancies produced by irradiation and the helium generated by transmutation in the nuclear fusion reactor, thereby improving the radiation resistance of the alloy. [5] Y 2 O 3 particles could be refined by the addition of Ti and Zr to the Fe matrix to form Y-Ti-O and Y-Zr-O clusters. [6,7] Ti and Zr elements could also form TiC, (Ti, W) C, (Ti, Ta) C, and V 3 Zr 3 C, which have strengthening effects similar to that of MX with Ta/V, to improve the high-temperature mechanical properties of steel alloys. [8,9] Ti and Zr are important alloying elements often used to prepare ODS steel. ODS RAFM alloys are commonly manufactured via powder metallurgy (PM), which involves mechanical alloying, hot powder consolidation (e.g., hot isostatic pressure, hot extrusion, or sparking-plasma sintering), and heat treatment. However, PM presents several inherent defects for the preparation of ODS alloys; for example, the technique could introduce impurities (e.g., O 2 ) to its complex processes, thereby inducing anisotropy in the microstructure and mechanical properties of the resulting alloys. [10] The technology also requires large amounts of energy and, at present, cannot be scaled up to industrial production.A demonstration nuclear fusion reactor requires over 11 000 tons of ODS RAFM steel as its structural material, [11] but PM technology for fabricating large-scale ODS steels has not yet been developed. This shortcoming is a basic defect of ODS RAFM steel production. Research on alternative preparation technologies for ODS steel is ongoing globally.Shi and Han directly added micron Y 2 O 3 powders to molten Fe alloy to prepare ODS steel by vacuum casting, forging, and heat treatment. [12] Analysis of the resulting alloys revealed complicated oxides containing Cr, Ti, Ta, Mn, V, Y, and O, which could prevent dislocations from gliding to improve the yield strength of the steel. Zhan et al. prepared 9Cr-ODS alloys by adding Y and Ti alloys to 9Cr steel through vacuum induction melting (VIM). [13] A large number of Y-Ti-O particles smaller than 0.5 μm were found in the steel, and the density of these particles reached 2.69 Â 10 19 m À3 ; this value is close to the density reported for 9Cr-ODS steel prepared by chemical reduction and mechanical milling (i.e., 5.7-8.1 Â 10 20 m À3 ). Oxygen carrier casting technology has been adopted to prepare ODS RAFM alloys by introducin...
“…The most important feature of the method is unidirectional solidification of a gas saturated melt that causes simultaneous formation of solid metal and gas pores, resulting in long cylindrical pores filled with hydrogen gas uniformly distributed in solid matrix [2]. Usually, the utilized gas is hydrogen and a great number of metal-hydrogen systems were investigated [1][2][3][4][5][6][7][8].…”
Section: Introductionmentioning
confidence: 99%
“…The ordered porous materials possess unique properties such as exceptionally low weight, special acoustic characteristics, and high damping capacity for absorption of mechanical energy [4][5][6][7][8]. Due to these unusual properties, ordered porous materials have potential applications in many fields like medicine, space technology, automotive and military industries etc.…”
Ordered porous copper with elongated pores has been fabricated by a continuous unidirectional solidification method in a hydrogen gas atmosphere with high pressure. The porosity of the ordered porous copper is significantly affected by the pressure of hydrogen. A theoretical model is developed to get the relation between the porosity and the processing parameters. The calculated values are in good agreement with the experimental results. Key words: Unidirectional solidification; Ordered porous copper; Porosity; Modeling.
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