Microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels

The microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels were studied by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and tensile test. The results show that Si can promote the transformation of austenite （γ） to f...

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Bibliographic Details
Published in:International journal of minerals, metallurgy and materials metallurgy and materials, 2012-10, Vol.19 (10), p.915-922
Main Authors: Wang, Zhi-gang, Zhao, Ai-min, Zhao, Zheng-zhi, Ye, Jie-yun, Tang, Di, Zhu, Guo-sen
Format: Article
Language:English
Subjects:
Carbon manganese steels
Ceramics
Characterization and Evaluation of Materials
Chemistry and Materials Science
Chromium
Composites
Corrosion and Coatings
Dual phase steels
Electron microscopy
Elongation
Glass
Hardening rate
High strength
Iron constituents
Manganese
Martensite
Martensitic transformations
Materials Science
Mechanical properties
Metallic Materials
Microstructure
Natural Materials
Niobium
Overaging
Retained austenite
Scanning electron microscopy
Silicon
Steel
Steels
Strain hardening
Surfaces and Interfaces
Tensile strength
Tensile tests
Thin Films
Tribology
力学性能
双相钢
扫描电子显微镜
显微组织
残留奥氏体
综合机械性能
超高强度
透射电子显微镜
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Summary:The microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels were studied by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and tensile test. The results show that Si can promote the transformation of austenite （γ） to ferrite （α）, enlarge the （α＋γ） region, and increase the aging stability of martensite by inhibiting carbide precipitation. Adding Cr leads to the formation of retained austenite and martensite/austenite （M/A） constituents, as well as the decomposi- tion of martensite during the overaging stage. Both of the steels show higher initial strain-hardening rates and two-stage strain-hardening characteristics. The C-Mn-Si-Nb steel shows the higher strain-hardening rate than the C-Mn-Cr-Nb steel in the first stage; however, there is no significant difference in the second stage. Although the tensile strength and elongation of the two steels both exceed 1000 MPa and 15%, respectively, the comprehensive mechanical properties of the C-Mn-Si-Nb steel are superior.
ISSN:1674-4799
1869-103X
DOI:10.1007/s12613-012-0647-6