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MA 316L ODS 및 Wet 316L ODS 스테인리스강에서 충격에너지에 미치는 소결 공정의 영향
김성수,한창희,장진성,Kim, Sung-Soo,Han, Chang-Hee,Jang, Jin-Sung 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.2
Two kinds of oxide-dispersion-strengthened (ODS) 316L stainless steel were manufactured using a wet mixing process(wet) and a mechanical alloying method (MA). An MA 316L ODS was prepared by a mixing of metal powder and a mechanical alloying process. A wet 316L ODS was manufactured by a wet mixing with 316L stainless steel powder. A solution of yttrium nitrate was dried after being in the wet 316L ODS alloy. The results showed that carbon and oxygen were effectively reduced during the degassing process before the hydroisostatic process (HIP) in both alloys. It appeared that the effect of HIP treatment on increase in impact energy was pronounced in the MA 316L ODS alloy. The MA 316L ODS alloy showed a higher yield strength and a smaller elongation, when compared to the wet 316L ODS alloy. This seemed to be attributed to the enhancement of bonding between oxide and matrix particles from HIP and to the presence of a finer oxide of about 20 nm from the MA process in the MA 316L ODS alloy.
Jung, Yang-Il,Kim, Hyun-Gil,Kim, Il-Hyun,Kim, Sun-Han,Park, Jung-Hwan,Park, Dong-Jun,Yang, Jae-Ho,Koo, Yang-Hyun Elsevier 2017 Materials & Design Vol.116 No.-
<P><B>Abstract</B></P> <P>The mechanical strength of Zircaloy-4 was enhanced by surface treatment consisting of laser beam scanning of an oxide-coated Zircaloy-4 sheet. An yttrium oxide (Y<SUB>2</SUB>O<SUB>3</SUB>) coating 7–55μm thick was applied to Zircaloy-4 sheets. Then, a laser beam was used to form a dispersed oxide layer on the Zircaloy-4 metal surface. The thickness of the dispersed oxide layer varied from 80 to 200μm depending on the process parameters. Tensile tests of samples having both surfaces treated were conducted at room temperature and 380°C. The tensile strength of Zircaloy-4 at room temperature was increased by up to 20% with the formation of a thin dispersed oxide layer with a thickness<10% of that of the Zircaloy-4 substrate. However, the tensile elongation of the samples decreased drastically. The decreased ductility became insignificant as the testing temperature increased to 380°C. The strengthening of the fabricated samples could be explained by two mechanisms: (i) oxide particles dispersed in the metallic matrix and (ii) the phase transformation in Zircaloy-4.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Laser beam treatment technology was developed for producing the oxide-dispersion-strengthened (ODS) Zircaloy-4. </LI> <LI> ODS Zircaloy-4 with increased strength was obtained by surface treatment to form a dispersed oxide layer. </LI> <LI> The strengthening was more effective at elevated temperature revealing the high toughness without brittle failure. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Surface treatment to form a dispersed Y<sub>2</sub>O<sub>3</sub> layer on Zircaloy-4 tubes
Jung, Yang-Il,Kim, Hyun-Gil,Guim, Hwan-Uk,Lim, Yoon-Soo,Park, Jung-Hwan,Park, Dong-Jun,Yang, Jae-Ho Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.429 No.-
<P><B>Abstract</B></P> <P>Zircaloy-4 is a traditional zirconium-based alloy developed for application in nuclear fuel cladding tubes. The surfaces of Zircaloy-4 tubes were treated using a laser beam to increase their mechanical strength. Laser beam scanning of a tube coated with yttrium oxide (Y<SUB>2</SUB>O<SUB>3</SUB>) resulted in the formation of a dispersed oxide layer in the tube’s surface region. Y<SUB>2</SUB>O<SUB>3</SUB> particles penetrated the Zircaloy-4 during the laser treatment and were distributed uniformly in the surface region. The thickness of the dispersed oxide layer varied from 50 to 140μm depending on the laser beam trajectory. The laser treatment also modified the texture of the tube. The preferred basal orientation along the normal to the tube surface disappeared, and a random structure appeared after laser processing. The most obvious result was an increase in the mechanical strength. The tensile strength of Zircaloy-4 increased by 10–20% with the formation of the dispersed oxide layer. The compressive yield stress also increased, by more than 15%. Brittle fracture was observed in the surface-treated samples during tensile and compressive deformation at room temperature; however, the fracture behavior was changed in ductile at elevated temperatures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Laser surface treatment technology was developed to form a dispersed oxide layer in Zircaloy-4. </LI> <LI> The treatment was effective in increasing the mechanical strength of Zircaloy-4 owing to oxide dispersion strengthening. </LI> <LI> Microstructural change in Zircaloy-4 is expected to enhance the dimensional stability in nuclear environment. </LI> </UL> </P>
Ahn, Jung-Ho,Kim, Tae Kyu,Ahn, Jeongsuk PAS 2017 ARCHIVES OF METALLURGY Vol.62 No.2
<P>In the present work, we have examined the effect of Ti on the properties of Fe-Y2O3 alloys. The result showed that the addition of Ti was effective for improving mechanical properties. This is due to the reduction of oxides by Ti during mechanical alloying and hot-consolidation. In particular, iron oxides are effectively reduced by the addition of Ti. Compared to the pristine Fe-Y2O3 alloys, titanium-added alloys exhibited fine and uniform microstructures, resulting in at least 60% higher tensile strength.</P>
Alloy 617계 산화물 분산강화(ODS) 합금의 제조와 인장특성
민형기,강석훈,김태규,한창희,김도향,장진성,Min, Hyoung-Kee,Kang, Suk-Hoon,Kim, Tae-Kyu,Han, Chang-Hee,Kim, Do-Hyang,Jang, Jin-Sung 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.6
Alloy 617, Ni-22Cr-12Co-9Mo base oxide dispersion strengthened alloy was fabricated by using mechanical alloying, hot isostatic pressing and hot rolling. Uniaxial tensile tests were performed at room temperature and at $700^{\circ}C$. Compared with the conventional Alloy 617, ODS alloy showed much higher yield strength and tensile strength, but lower elongation. Fracture surfaces of the tensile tested specimens were investigated in order to find out the mechanism of fracture mode at each test temperature. Grain adjustment during tensile deformation was analyzed by electron backscattered diffraction mapping, inverse pole figures and TEM observation.
Development of Fe-12%Cr Mechanical-Alloyed Nano-Sized ODS Heat-Resistant Ferritic Alloys
Kim, Ick-Soo,Choi, Byung-Young 대한금속학회 2002 METALS AND MATERIALS International Vol.8 No.3
The development of mechanical alloying (MA)-oxide dispersion strengthened (ODS) heat-resistant ferritic alloys of Fe-12%Cr with W, Ti and Y_2O_3 additions were carried out. Fe-12%Cr alloys with 3%W, 0.4%Ti and 0.25% Y_2O_3 additions showed a much finer and more uniform dispersion of oxide particles among the alloy system studied. Nano-sized oxides dispersed in the alloys suppress the grain growth during annealing at a high temperature and resulted in the remarkable improvement of creep strength. The oxide phase was identified as a complex oxide type of Y-Ti-O.
Park, E.K.,Hong, S.M.,Lee, G.J.,Park, J.J.,Lee, M.K.,Lee, J.G.,Seol, K.W. Pergamon 2016 Scripta materialia Vol.113 No.-
We report a dramatic suppression of argon bubble formation in oxide dispersion strengthened steels through a high-energy mechanical alloying route. The volume fraction of argon bubbles trapped at the surface of the oxide particles is greatly reduced from 2.1x10<SUP>-3</SUP> to 1.4x10<SUP>-4</SUP>%, when the milling energy input rate is increased from 20 to 190kJ/g@?hit. It is found that the higher milling energy, associated with a reduction of milling time, yields reduced argon contamination of the ball-milled powders, leading to enhanced microstructural homogeneity in consolidated oxide dispersion strengthened steels.
Fe-5Y2O3 조성의 기계적 합금화 분말에 형성된 산화물의 상변태 거동
김가언,최정선,노상훈,강석훈,최병권,김영도,김태규 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.5
The phase transformation behavior of the oxides formed in mechanically alloyed Fe-5Y2O3 powder is investigated. Non-stoichiometric Y-rich and Fe-rich oxides with sizes of less than 300 nm are observed in the mechanically alloyed powder. The diffusion and redistribution reactions of the elements in these oxides during heating of the powder above 800 ℃ were observed, and these reactions result in the formation of a Y3Fe5O12 phase after heating at 1050 ℃. Thus, it is considered that the Y2O3 powder and some Fe powder are formed from the non-stoichiometric Y-rich and Fe-rich oxides after the mechanical alloying process, and a considerable energy accumulated during the mechanical alloying process leads to a phase transformation of the Y-rich and Fe-rich oxides to YαFeβOγ-type phase during heating.
Park, Eun-Kwang,Hong, Sung-Mo,Park, Jin-Ju,Lee, Min-Ku,Rhee, Chang-Kyu,Seol, Kyeong-Won The Korean Powder Metallurgy Institute 2013 한국분말재료학회지 (KPMI) Vol.20 No.4
Fe-based oxide dispersion strengthened (ODS) powders were produced by high energy ball milling, followed by spark plasma sintering (SPS) for consolidation. The mixed powders of 84Fe-14Cr-$2Y_2O_3$ (wt%) were mechanically milled for 10 and 90 mins, and then consolidated at different temperatures ($900{\sim}1100^{\circ}C$). Mechanically-Alloyed (MAed) particles were examined by means of cross-sectional images using scanning electron microscopy (SEM). Both mechanical alloying and sintering behavior was investigated by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM). To confirm the thermal behavior of $Y_2O_3$, a replica method was applied after the SPS process. From the SEM observation, MAed powders milled for 10 min showed a lamella structure consisting of rich regions of Fe and Cr, while both regions were fully alloyed after 90 min. The results of sintering behavior clearly indicate that as the SPS temperature increased, micro-sized defects decreased and the density of consolidated ODS alloys increased. TEM images revealed that precipitates smaller than 50 nm consisted of $YCrO_3$.
Effect of thermal ageing on mechanical properties of a high-strength ODS alloy
Sunghoon Hong,김성환,김태규,장창희 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10
A new high-strength ODS alloy, ARROS, was recently developed for the application as the cladding material of a Sodium-cooled fast reactor (SFR). To assess the long-term integrity under thermal ageing, ARROS was thermally aged in air at 650 o C for 1000 h. The degree of thermal ageing was assessed by mechanical tests such as uniaxial tensile, hardness, and small punch tests at from room temperature to 650 o C. Tensile strength was slightly decreased but elongation, hardness, and small punch energy were hardly changed at all test temperatures for the specimen aged at 650 o C for 1000 h. However, the variation in mechanical properties such as hardness and small punch energy increased after thermal ageing. Using the test results, the correlation between tensile strength and maximum small punch load was established.