Retained Austenite Attributes and Mechanical Performance of Different Compositions of TRIP Steel Alloys
- Central Metallurgical R&D Institute (CMRDI) (Egypt)
- Suez University, Faculty of Engineering (Egypt)
The main objective of this work is to correlate the different attributes of retained austenite phase in TRIP steel structure with its mechanical properties. Three different chemical compositions were used to produce TRIP steel alloys. The first alloy contains only silicon as a carbide precipitation inhibitor; in the second alloy, silicon is partially replaced with aluminum, while in the third alloy phosphorus is added to the silicon–aluminum alloy. These compositions were proposed in order to avoid the negative effect of silicon during galvanizing. These three steel alloys were cast, homogenized, hot-forged and then subjected to intercritical annealing treatment followed by cooling and isothermal treatment in salt bath with subsequent air-cooling. Microstructural characterization, using optical microscope, SEM and XRD, along with tensile testing was carried out. Retained austenite attributes include volume fraction, carbon content, total carbon content, retained austenite transformable index and its stability coefficient against strain-induced martensite (SIM) transformation. The effect of these attributes on the mechanical properties of the studied TRIP steel alloys was evaluated using tensile test date, i.e., ultimate tensile strength (UTS), ductility, yield strength to UTS ratio, performance index and strain-hardening exponent. The variation of strain-hardening rate and strain-hardening exponent with strain was also considered. The failure behavior of the studied steel alloys was investigated using SEM on tensile-tested specimens. The results show that Si/Al-alloy has the lowest retained austenite transformable index, lowest stability coefficient against SIM transformation, highest performance index and more stable and uniform variation in strain-hardening rate and strain-hardening exponent with strain. These properties satisfy the industrial constrains of the sheets used in automotive industry relating to better mechanical properties and galvanizability.
- OSTI ID:
- 22970827
- Journal Information:
- Journal of Materials Engineering and Performance, Vol. 28, Issue 4; Conference: AeroMat 2018: 29. Advanced Aerospace Materials and Processes (AeroMat) Conference and Exposition, Orlando, FL (United States), 7-10 May 2018; Other Information: Copyright (c) 2019 ASM International; Country of input: International Atomic Energy Agency (IAEA); ISSN 1059-9495
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM ALLOYS
AUSTENITE
CHEMICAL COMPOSITION
COEFFICIENT OF PERFORMANCE
DUCTILITY
ION MICROPROBE ANALYSIS
MARTENSITE
MASS SPECTROSCOPY
OPTICAL MICROSCOPES
SCANNING ELECTRON MICROSCOPY
SILICON ALLOYS
SILICON CARBIDES
STEELS
STRAIN HARDENING
TRANSFORMATIONS
X-RAY DIFFRACTION
YIELD STRENGTH