A Novel Mo and Nb Microalloyed Medium Mn TRIP Steel with Maximal Ultimate Strength and Moderate Ductility
- PDF / 2,720,878 Bytes
- 11 Pages / 593.972 x 792 pts Page_size
- 64 Downloads / 210 Views
TRODUCTION
DUE to an increasing demand for energy conservation and safety requirements in the automotive industry, extensive efforts have recently been devoted to design lightweight auto bodies with enhanced crash resistance. Manganese-based transformation-induced plasticity (TRIP)-assisted steels, which are characterized by being multi-phase, metastable, and multi-scale (so-called as M3),[1] may be promising candidates for automotive application due to their outstanding combination of strength and ductility, as well as excellent energy absorption capacity. First reported by Miller in the 1970s,[2] TRIPassisted steels containing 5 pct Mn have attracted renewed interest with many studies recently conducted to better understand the effects of processing parameters on the resulting microstructure and mechanical properties.[3–10] More recently, several microstructure-sensitive design concepts associated with alloy composition have been proposed to stabilize the austenite at room temperature. One strategy was to alter the C/Mn contents of Fe-(0.20.4)C-(5-7) Mn (wt pct) TRIP steels that were produced by the austenite-reverted transformation (ART).[3] The results demonstrated that with increasing C or Mn
MINGHUI CAI, Associate Research Fellow, QI CHAO, Ph.D. Student, and PETER D. HODGSON, Director, Australian Laureate Fellow, Alfred Deakin Professor, are with the Institute for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Geelong, VIC 3217, Australia. Contact e-mail: [email protected], [email protected] ZHUN LI, Technician, is with the National Engineering Research Center for Silicon Steel, Wuhan Iron and Steel Company, Wuhan 430081, P.R. China. Manuscript submitted August 19, 2013. Article published online August 8, 2014 5624—VOLUME 45A, NOVEMBER 2014
content, the thermal stability of austenite considerably increased at the expense of mechanical stability. Suh et al.[4,5] developed another microstructural control strategy using Al for application in modern continuous annealing conditions for cold-rolled Mn-TRIP steels. An addition of 3 pct Al to the Fe-0.12C-5Mn-0.5Si alloy limited the austenite fraction to 20 to 30 pct in the temperature range from 973 K to 1073 K (700 C to 800 C), at which recrystallization of the deformed matrix readily occurred. However, the resulting yield strength only ranged from 444 to 814 MPa with a total elongation of 11 to 24 pct.[4] Although the Fe-(0.1-0.4)C-(3-7)Mn-(1-3)Al TRIP steel possesses a good strength-ductility balance resulting from grain ultra-refinement and the continuous TRIP effect during tensile deformation, some issues such as low yield strength and segregation of Mn still remain.[11,12] Thus, the aim of the current study was first to propose a novel Mo and Nb alloying concept for medium Mn TRIP steels to overcome the abovementioned problems because they reduce the tendency of Mn and Al to segregate during casting and hotforming [11,12] due to the overall refinement of the structure by Nb microalloying, raise the yield stress by grain refinement, precipi
Data Loading...
