o22-thermodynamic database of high-strength low-density steels
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Ikuo OHNUMA, Naohide KAMIYA, Yuji SUTO, Toshihiro OMORI,
Thermodynamic Database of High-Strength Low-Density Steels
Ryosuke KAINUMA and Kiyohito ISHIDA
Department of Materials Science,
Tohoku University, Sendai, JAPAN
TOFA2010, September 14, 2010 @Porto
Contents
� Thermodynamic Database of Steels.
� Application of Thermodynamic D.B. (1) Fe-Mn-Al-Cr-C System(2) Low-Density & High-Strength Steels
� Mechanical Properties of Low-Density & High-Strength Steels
Background: High-Strength & Low Density Steel
Thermodynamic Database of Steels for various Systems
Application of Thermodynamic D.B.- High-Strength Low-Density Steels
Alloy Design of Lightweight Steels
Effect of Alloying Elements on Density of γγγγ-Fe
Lightweight Steels by Al & SiEmbrittlement due to Ordering
Alloy Design of High-strength & Lightweight Steels
High-Strength Low-Density Steels:Thermodynamic D.B. + Density
High-Strength Low-Density Steels:Density Calculation of γγγγ-Fe
Precipitation of κκκκ-carbide in γγγγ-Fe
Experimental Procedures
Homogenization(1200℃)℃ ℃
Alloys Induction Melting
Equilibrium Composition
EPMA(mass%C was determined by calibration curve method.)
Microstructure Optical Microscope
Heat TreatmentHomogenization(1200℃)Equilibration(800℃~~~~1200℃)
Thermodynamic Models
Liquid:Sub-regular Solution ApproximationSolids(γγγγ-Fe, αααα-Fe, κκκκ):Sub-lattice Model
Large Solubility of κκκκ
Thermodynamic Modelsー L12 Ordering in FCC Phase
Liquid:Sub-regular Solution ApproximationSolids(γγγγ-Fe, αααα-Fe, κκκκ):Sub-lattice Model
Thermodynamic Models
High-Strength Low-Density Steels:Thermodynamic D.B.
Results of Calculation (1)---- Fe-Mn-Al System
R. Umino et al., J. Phase Equilibr.& Diffusion., 27 (2006) 54-62.
Results of Calculation (2)---- Fe-Al-C System
Results of Calculation (3)---- Mn-Al-C System
Results of Calculation (4)---- Fe-Mn-Al-C System
High-Strength Low-Density Steels:Alloy Design
Strategy of Alloy DesignFe-Mn-Al-Cr-C Alloys.
(1) Reduce Density Light elements (Al, C & Mn)
γγγγ γ γ γ γ (2) Stabilize γγγγ-Fe γ γ γ γ stabilizing elements (C & Mn)
(3) Corrosion resist. Cr
(4) Precipitation of Appropriate aging & κκκκ-Carbide cooling
(1) Fe-Al-C ternary alloys: Alloy Design of Low-Density γγγγ-Fe
(2) Effect of Mn on Density & γγγγ-Fe- Fe-8Al-1C +Mn
(2) Effect of Mn on Density & γγγγ-Fe- Fe-10Al-1C +Mn
(3) Optimization of C content- Fe-20Mn-xAl +C
(4) Optimization of Cr content- Fe-20Mn-10Al-1.5C +Cr
(5) Summary of Alloy Design - Fe-20Mn-10Al-5Cr-1.5C Alloy
Experimental Procedures: Mechanical Properties
As-Quenched (W.Q.) Microstructure(Fe-20Mn-5Cr-10Al-1.5C)
Microstructures after A.C.(Fe-20Mn-5Cr-10Al-1.5C)
Results of Tensile Test(Fe-20Mn-5Cr-xAl-yC)
Microstructures by TEM(Fe-20Mn-5Cr-10Al-1.5C :1100℃℃℃℃)
<100> γ γ γ γ //<100> κκκκ
Low Work-Hardening (LWH)(Fe-20Mn-5Cr-xAl-yC)
Comparison of Mech. Properties with other materials
Summary
� Thermodynamic Database of Steels.⇒⇒⇒⇒ Fe-Mn-Al-Cr-C (-Si) System
� Application of Thermodynamic D.B. ⇒⇒⇒⇒
⇒⇒⇒⇒
� Application of Thermodynamic D.B. ⇒⇒⇒⇒ γγγγ-Fe + κκκκ-Carbide with
Low-Density(~6.6 g/cm3)� Mechanical Properties ⇒⇒⇒⇒ High-Strength(~1200MPa) &
Low Work Hardening Steels
Thank you for your attention. Thank you for your attention.
CALPHAD(CALculation of PHAse Diagrams)
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