36 Result(s)
within
Changhee Lee
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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Article
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
Nature of nonmetallic inclusions in electrogas weld metal
An electrogas weld metal deposited with an approximately 20 kJ/mm heat input was examined to investigate the chemical and microstructural characteristics of nonmetallic inclusions related to the weld microstru...
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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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Article
Characterization of the local brittle layer formed in electro-gas weld metals
The microstructural characteristics of the local brittle layer (LBL) reported to be formed at the weld center of tandem electro-gas (EG) weld made with EG70T-G wire have been investigated to identify the criti...
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Article
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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Article
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
Local variation of impact toughness in tandem electro-gas welded joint
To identify the microstructural factors causing the local brittleness in electro-gas (EG) welded joint, this study investigated the EG welded joints produced by tandem EGW process using two different ship-grad...
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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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Article
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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Article
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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Article
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
Formation of Mn-depleted zone in Ti-containing weld metals
Characteristics of non-metallic inclusions are studied using three shielded metal arc (SMA) weld metals which differ greatly in Ti content and are correlated with the acicular ferrite contents measured in the ...
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Article
Effect of titanium content on weld microstructure and mechanical properties of bainitic GMA welds
The effects of titanium content on the weld microstructure, mechanical properties, and inclusion characteristics were investigated in the as-deposited bainitic GMA weld metals having nearly constant level of o...
