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<i>In Situ</i> Neutron Diffraction Measurements of the Deformation Behavior in High Manganese Steels
Kang, Mihyun,Woo, Wan Chuck,Em, Vyacheslav,Lee, Young Kook,Seong, Baek Seok Trans Tech Publications, Ltd. 2014 Materials science forum Vol.772 No.-
<P>Deformation behavior of high Mn TWIP (twinning induced plasticity) steels was observed using neutron diffraction. Two kinds of specimens were prepared; 0 and 2 wt% of Al TWIP steels. The lattice strains and peak widths of hkl grains were measured under tensile loading. The results provide an insight into the influence of the Al contents on the deformation behavior associated with the microstructure changes in TWIP steels.</P>
Lee, Soo Yeol,Woo, Wan Chuck,Gharghouri, Michael A.,Yoon, Cheol,An, Ke Trans Tech Publications, Ltd. 2014 Materials science forum Vol.777 No.-
<P>In-situ neutron diffraction experiments were employed to investigate the micromechanical behavior of solid-solution-strengthened Mg-1wt.%Al alloy. Two starting textures were used: 1) as-extruded then solutionized texture, T1, in which the basal poles of most grains are tilted around 70~85° from the extrusion axis, and 2) a reoriented texture, T2, in which the basal poles of most grains are tilted around 10~20° from the extrusion axis. Lattice strains and diffraction peak intensity variations were measured in situ during loading-unloading cycles in uniaxial tension. Twinning activities and stress states for various grain orientations were revealed. The results show that the soft grain orientations, favorably oriented for either extension twinning or basal slip, exhibit stress relaxation, resulting in compressive residual strain after unloading. On the other hand, the hard grain orientations, unfavorably oriented for both extension twinning and basal slip, carry more applied load, leading to much higher lattice strains during loading followed by tensile residual strains upon unloading.</P>
Baik, Youl,Kang, Bo Kyeong,Choi, Yong,Woo, Wan Chuck Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6
The effect of gadolinium and boron on the texture development and magnetic properties of the texture controlled 23Cr-10NiCu duplex stainless steels were studied to develop a high performance neutron and electromagnetic shielding material. The 23Cr-10NiCu base alloy is composed of 60% of austenite and 40% of ferrite, whereas, the 23Cr-10NiCu-0.5Gd-0.8B modified alloy is composed of 66% of austenite, 27% of ferrite and 7% of CrFeB intermetallic compounds. The gadolinium and boron addition to the 23Cr-10NiCu base alloy increased mechanical properties. Microstructure observation showed that the small addition of 0.5 wt% gadolinium and 0.8 wt% boron to the alloy retarded to form texture at the same hot rolling conditions, and improved the maximum magnetism, residual magnetism and coercive force about 3%, 122% and 120%, respectively.
안규백(Gyubaek An),한일욱(Illwook Han),박정웅(Jeongung Park),우완측(Wan Chuck Woo) 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.6
As the recession in shipbuilding industry became longer, domestic shipbuilders focused on the need for high value added and high technology, and strived to build safer vessels. There are LNG carriers and container ships that require representative technologies. Both ship types are rapidly increasing ship size in the 2000s. Recently, there have been the increase of ship size and the development of oil and gas in arctic region. These trends have led to the requirements such as high strength, good toughness at low temperature and good weldability for prevent of brittle fracture at service temperature. Studies on unstable fracture have mainly been conducted to evaluate the brittle crack stopping properties of the high strength steel welded joints through large scale fracture tests, and studies on the difficulty of stopping brittle cracks in welded joints. It is known that BCA (Brittle Crack Arrest) steel has recently been developed to prevent unstable fracture if cracks propagate toward the BCA steel even if brittle cracks occur. Therefore, it is considered that the ship can be dried more easily if a technology capable of inducing the brittle crack to the BCA steel is developed. In this study, we describe a technique for securing unsafe fracture safety by inducing cracks toward the BCA steel, which has excellent brittle crack stopping ability, regardless of the welding process when brittle cracks occur in the superstructure of super large container ships.
Kim, Yanghoo,Kim, Yong Min,Koh, Ji-Yeon,Lee, Tae-Ho,Woo, Wan Chuck,Han, Heung Nam Pergamon 2016 Scripta materialia Vol.119 No.-
<P><B>Abstract</B></P> <P>Single crystal elastic constants of austenite and ferrite phases in high-nitrogen duplex stainless steel were evaluated by an elastic self-consistent model combined with an optimization process using <I>in-situ</I> neutron diffraction data. The optimized elastic constants were validated by the indentation moduli of each phase obtained by nanoindentation. In addition, the stacking fault energy of austenite was evaluated based on the neutron diffraction profile and the single crystal elastic constants and was subsequently correlated with the observed deformation microstructure.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>