Abstract
This study is concerned with the influence of strain rate on the plastic deformation behavior and microstructure variables of AZ31 magnesium alloy sheet. The tensile properties were measured at room temperature at a strain rate of 0.001 and 100 s–1 using a universal tensile testing machine and servo-hydraulic high-speed tensile..... More

Abstract
Aluminum alloys have been widely used for aerospace applications due to their high strength and lightweight. New demand is growing for aluminum alloys with high temperature mechanical properties that can sustain plastic deformation at high temperature. In this study, correlations among microstructure, tensile properties and Charpy impact properties were analyzed..... More

Abstract
The hot crack resistance and mechanical properties of flux cored arc (FCA) welds were investigated with three kinds of welding consumables having different boron (B) and manganese (Mn) contents for high strength carbon steel. The hot crack resistance, measured from self-restraint testing, strongly depended on the amount of B in..... More

Abstract
The basic oxygen furnace (BOF) steelmaking process in the steel industry is highly complicated, and subject to variations in raw material composition. During the BOF steelmaking process, it is essential to maintain the carbon content and the endpoint temperature at their set points in the liquid steel. This paper presents..... More

Abstract
The effects of tempering condition on the microstructure and mechanical properties of 30MnB5 hot stamping steel were investigated in this study. Before the tempering, hot-stamped 30MnB5 steel was composed of only α′-martensite microstructure without precipitates. After the tempering at 180 ℃ for 120 min, nano-sized ε-carbides were precipitated in the..... More

Abstract
Directional solidification experiments were carried out to estimate the effect of solidification velocity and temperature gradient on primary dendrite arm spacing (PDAS) in the Ni-based superalloy, CMSX-4 alloy. The specimens were solidified at velocities of 1, 5, 25, 50 and 100 mm/s under given temperature gradients of 12.5, 18, 23..... More

Abstract
This study evaluated the relationship between reheat cracking that occurs in the reheated weld zone formed by subsequent multi-pass welding and the preheat/interpass temperature. The multi-pass weldment was YP 690 MPa high-strength steel, which is used in mobile offshore platform units. The welding process was flux-cored arc welding (FCAW), which..... More

Abstract
A Ni-Cr-B-Si-C coating layer was manufactured on a plate of Fe base alloy using a laser cladding process, and the microstructural and mechanical properties of the laser cladded coating layer and a Ni electroplating layer (used as a reference material) were investigated. To identify the microstructural and mechanical properties, scanning..... More

Abstract
Microstructure evolution and the creep fracture characteristics of dissimilar welds between Ni-based superalloy Inconel 740H and High Cr ferritic steel Gr.92 were investigated. The dissimilar welds were fabricated by shielded metal arc (SMA) welding process with Ni-based austenitic Inconel 182 superalloy. Postweld heat treatment at 760 ^oC for 4 hours..... More

Abstract
This study was carried out to investigate the effect of thermo-mechanical treatment on the formation behavior of martensite in 316L stainless steel. Dislocation, α' and ε-martensite were formed by thermo-mechanical treatment. Martensite with surface relief and specific direction was formed by thermo-mechanical treatment. Martensite formed by thermo-mechanical treatment were reversed..... More

Abstract
In this study, the effects of hot forging and heat treatment (quenching and tempering) of cast Cr alloy steel on the microstructures and mechanical properties were investigated. The hot forging was performed at a compressive ratio 0.5 at 1,250 ^oC. The heat treatment process was quenching (860 ^oC for 2..... More

Abstract
This study manufactured Fe-Cr-Ni-based alloy (HK30) using the metal injection molding (MIM) process and investigated the microstructure and room·high temperature mechanical properties of the material. The effect of hot isostatic pressing (HIP) on properties was also examined. The average grain sizes were 24.1 µm for an MIM specimen and 29.1..... More

Abstract
This study investigated the microstructure and the ambient-elevated temperature compression and elevated temperature creep properties of Fe-14Cr ferritic ODS steel manufactured by mechanical alloying (high energy ball milling) and hot extrusion processes. Initial microstructural observation of the as-extruded material identified elongated grains in the direction of extrusion; however, some recrystallization..... More

Abstract
A polycrystalline diamond compact (PDC) is a two-stage sintered body manufactured by placing diamond powders on a WC-Co hard material and then applying the high pressure high temperature (HPHT) sintering process. This study investigated the microstructure and wear properties of the PDC depending on initial diamond particle size. Three different..... More

Abstract
Age hardening and re-crystallization softening of a type of high entropy alloy, CoCrFeMnNi, was performed to investigate the relationship between microstructure and the property of mechanical hardness. Equiatomic CoCrFeMnNi was produced by casting followed by homogenizing, cold rolling and post heat treatments. TEM analysis revealed that the microstructure of the..... More

Abstract
Spent nuclear fuel is stored and transported in cask bodies, but they become embrittled with the passage of time resulting in lattice defects due to neutron irradiation. Cask bodies made by the quenching and tempering (QT) treatment are not safe and are hard to store because of embrittlement caused by..... More

Abstract
A new Ni based superalloy is considered as bucket material because of high fatigue resistance with fine grain. However a bucket is usually exposed to high temperature for a long time, so creep rupture tests were conducted to understand the microstructure evolution during creep deformation under various stresses at temperatures..... More

Abstract
The hot deformation behavior of as-cast and homogenized Fe-22Cr-9.5Mn-3.3Ni stainless steel was investigated over a temperature range between 600~1,250 ℃. The deformability of the as-cast Fe-22Cr-9.5Mn-3.3Ni steel decreased with increasing temperature up to 850 ℃, and then increased at temperatures between 900 and 1200 ℃ caused by dynamic recrystallization at..... More

Abstract
A feasibility study on microstructure design has been carried out to improve creep rupture life in alumina-forming austenitic (AFA) Fe-14Cr-20Ni-2.3Al stainless steel with and without 2 wt% W addition. After creep tests under 780 °C/80 MPa conditions, it was observed that internal cracks initiated primarily from grain boundaries in the..... More

Abstract
The influence of ultrasonic melt treatment (UST) combined with a change in cooling rates on the microstructure and elevated temperature mechanical properties of a hypereutectic Al-18Si-4Cu-3Ni piston alloy was investigated. Microstructural observation confirmed that UST effectively refined the sizes of primary Si and intermetallic compounds (e.g. ε-Al₃Ni) while promoting their..... More

Abstract
An as-received EMC/S (electromagnetic casting and stirring)-processed Al-12Si based alloy billet was homogenized to examine its microstructure and high temperature plastic deformation behavior, using compressive tests over the temperature range from 623 to 743 K and a strain rate range from 1.0×10^-3 to 1.0×10⁰s^-1. The results were compared with samples..... More

Abstract
High speed and large capacity optical communication networks are needed to meet the demands of increased traffic being created by mobile services. Advanced optical communication systems are based on high performance optical device modules that have small footprints and low power consumption. A microlens with a short coupling length and..... More

Abstract
An AlCrTiSiN film composed of 31Al-15Cr-1.7Ti-0.5Si-51.8N (at%) was deposited on a steel substrate by arc ion plating to a thickness of 1 μm. It consisted of nano crystalline hcp-AlN and fcc-CrN. Its corrosion behavior in Ar-1%SO₂ gas at 800 ℃ for 5-50 h was studied. The resulting scales consisted primarily..... More

Abstract
A composite having 60 vol% of TiC particles was successfully fabricated by the infiltration of molten SKD11 tool steel into a TiC preform. The density of this composite was achieved to be 25% lighter than conventional steels. The penetration of the liquid metal reached geometrically complex regions without any interfacial..... More

Abstract
The effects of alloying elements (Mn, Cr, and C) on the corrosion resistance of steel were examined using weight loss test, polarization test in a sour environment, analysis of rust, and the prediction of stable corrosion product. Carbon was found to improve corrosion resistance after 7-day immersion, while manganese and..... More

Materials Analysis & Characterization

Abstract
Micro-twinning has been investigated in some state-of-the-art materials by transmission electron microscopy, but such characterizations have not been clear so far. Micro-twins must be characterized by identifying their spots in the electron diffraction pattern, which is very unique compared to normal defects such as dislocations or stacking..... More

Corrosion & Surface Treatment

Abstract
Vacuum kinetic spraying (VKS) is a relatively advanced process, by which a dense film can be fabricated at room temperature. Various materials including ceramic, metal, polymer and composite can be used as the substrate and coating materials. In this research, red and blue color films were successfully fabricated on glass..... More