30 Result(s)
within
Article
Changhee Lee
English
Characterization and Evaluation of Materials
Metallic Materials
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Article
Heat-Affected Zone Characteristics with Post-Weld Heat Treatments in Austenitic Fe–Mn–Al–C Lightweight Steels
This study investigates the relationship between the mechanical characteristics and microstructural transitions in heat-affected zone (HAZ) of various austenitic Fe–Mn–Al–C lightweight steels. The analysis was...
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Correlation Between Constituent Phase and Weld Metal Properties in Ni-Reduced Duplex Stainless Steel
The intrinsic properties of austenite and ferrite on the mechanical properties and corrosion resistance of the duplex stainless steel weld metals was studied by substituting Ni with Mn, N, and Mn + N. The prop...
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Kinetics Study on Low-Temperature Tempering of Martensitic Phase in Medium Mn Steel Weldment During Paint-Baking Heat Treatment
The kinetics of low-temperature tempering in a dissimilar resistance spot weldment between medium Mn transformation-induced plasticity (MT) steel and dual-phase (DP) steel were investigated to interpret the ch...
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Article
Effect of Surface Smoothness on the Structure of Scale and Formation of Surface Cracks in TiAl Alloys under Heat Treatment
The methods of optical and electron microscopy are used to study the relation between the processes of scale formation and propagation of surface cracks in TiAl alloys under heat treatment. It is shown that cr...
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Article
Surface Metallization and Ceramic Deposition on Thermoplastic-Polymer and Thermosetting-Polymer Composite Via Atmospheric Plasma Spraying
A spray coating technique is an excellent method for surface metallization and ceramic deposition to widen the application fields of irreplaceable engineering polymers. In this study, Al metallization and Al2O3 d...
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Article
Fusion Weldabilities of Advanced High Manganese Steels: A Review
A large amount of manganese has been added to next-generation advanced high strength steels for automotive applications. The increased manganese content changes the microstructural and mechanical characteristi...
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Microstructural and Inclusion Characteristics of C–Mn Steel Welds at a Minimal Level of Titanium
To better determine the lower limit of titanium content for the formation of acicular ferrite, C–Mn steel welds varying the titanium concentration at a minimal level from nearly zero to about 30 ppm have been ...
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Tribological and Microstructural Properties of Carbon Steel Coatings Fabricated by Wire Arc Spray
Thermal spray is a widely used process employed for the reduction of engine weight by replacing heavy cast iron liners inserted in cylinder bores. In particular, twin wire arc spray (TWAS) is one of the most p...
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Article
Roles of (Fe, Mn)3Al Precipitates and MBIP on the Hot Ductility Behavior of Fe–30Mn–9Al–0.9C Lightweight Steels
In the automotive industry, lightweight steel has received much attention because steel comprises a significant portion of a vehicle’s total weight. Fe–Mn–Al–C steel is a representative lightweight steel due t...
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Formation of Secondary Phases and Their Effect on the Mechanical Properties of Joints Formed by TLP Bonding Using Fe–B–Si Insert Metal in Duplex Stainless Steel
We studied the effects of secondary phases on the mechanical properties of joints formed by transient liquid-phase bonding in nitrogen-containing duplex stainless steel UNS S32750. Transient liquid-phase bondi...
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Characterization of Mechanical and Metallurgical Notch Effects of DP980 Steel Weld Joints in Fatigue Performance
This work investigates the use of 980 MPa grade dual-phase (DP) steel joints with pulsed current gas metal arc welding (P-GMAW) for reliable weld performance by comparing actual welded joints with thermo-mecha...
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Article
Correlation Between Microstructure and Low-Temperature Impact Toughness of Simulated Reheated Zones in the Multi-pass Weld Metal of High-Strength Steel
A large fraction of reheated weld metal is formed during multi-pass welding, which significantly affects the mechanical properties (especially toughness) of welded structures. In this study, the low-temperatur...
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Microstructure Evolution and Age-Hardening Behavior of Microalloyed Austenitic Fe-30Mn-9Al-0.9C Light-Weight Steels
The aging behavior and mechanical properties of microalloyed austenitic Fe-30Mn-9Al-0.9C light-weight steels were investigated through transmission electron microscopy analysis, electron backscatter diffractio...
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Article
Factors Affecting the Inclusion Potency for Acicular Ferrite Nucleation in High-Strength Steel Welds
Factors affecting the inclusion potency for acicular ferrite nucleation in high-strength weld metals were investigated and the contribution of each factor was qualitatively evaluated. Two kinds of weld metals ...
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Article
Variation in the Chemical Driving Force for Intragranular Nucleation in the Multi-pass Weld Metal of Ti-Containing High-Strength Low-Alloy Steel
The variation of the Mn-depleted zone (MDZ) around the inclusion during multi-pass welding of Ti-containing high-strength low-alloy (HSLA) steel was investigated by taking the changes in the impact toughness a...
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Article
Mn-Depleted Zone Formation in Rapidly Cooled High-Strength Low-Alloy Steel Welds
The mechanism of formation of an Mn-depleted zone (MDZ) near the inclusion in a steel weld was elucidated based on quantification of MDZ depth and thermodynamic calculations. The effective inclusion phase for ...
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Article
Oxide Formation Mechanisms in High Manganese Steel Welds
Oxide inclusions in high-Mn steel welds were analyzed and almost all of which were found to belong to the MnO-Al2O3-SiO2 system. In this study, the inclusions were categorized based on MnS morphology into the fol...
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Article
Influence of Ti on non-metallic inclusion formation and acicular ferrite nucleation in high-strength low-alloy steel weld metals
The phase transition behaviors of non-metallic inclusions as a function of Ti content were investigated by monitoring changes in the microstructure and mechanical properties of high-strength low-alloy steel mu...
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Article
Manufacturing and Compressive Deformation Behavior of High-Strength Aluminum Coating Material Fabricated by Kinetic Spray Process
The compressive deformation behavior in the thickness direction of a kinetic-sprayed pure-aluminum layer whose thickness is ~15 mm was investigated. The yield strength of coating material was 200 MPa, and a un...
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Article
Restoration of face-centered cubic metals subjected to kinetic spraying
Deformation mode and restoration of face-centered cubic (FCC) metal (Al, Ni, and Cu) particles subjected to kinetic spraying (KS) were investigated. The FCC metal particles were accelerated to supersonic veloc...
