High-rate tensile properties of Si-reduced TRIP sheet steels

Abstract

There have been efforts to develop Si-reduced TRIP steels to improve the wettability of Zn coatings, since the conventional CMnSi-TRIP steels suffer from poor galvanizability. In addition, for the development of potential applications of Si-reduced TRIP steels in vehicle crash management, a better understanding of high strain rate properties is required. In the present study, the effects of alloying elements, such as Cu, Al, Si, and P, on the high-rate tensile properties of Si-reduced TRIP sheet steels were investigated. Tensile tests were performed with a servo-hydraulic tensile testing machine at strain rates ranging from 10 −2 to 6 × 10 2 s −1, and the ultimate tensile strength, elongation, strain rate sensitivity, and absorbed energy were evaluated. The retained austenite volume fractions and carbon content of the specimens were measured using neutron diffraction. The UTS was increased with Cu, Al, Si, and P alloying throughout the strain rate range, and the alloying effect on UTS was considerable with Cu and P. The effects of alloying on the microstructure were not significant. All the steels tested in this study exhibited positive strain rate sensitivity, and the m value at strain rates higher than 10 s −1 was at least two times higher than that at lower strain rates.

Effect of alloying elements on expulsion in electric resistance spot welding of advanced high strength steels

“…Alloying elements, such as Cr, Si, Mn, Al and B, are added to improve the formability of these steels. 6, 7 As the quantity of alloying elements added is increased, the mechanical properties of the welded and base metals are affected. In particular, the amount of alloying element has an effect on the lobe curve, which is an indicator of the weldability of the RSW.…”

Serration Phenomena Occurring During Tensile Tests of Three High-Manganese Twinning-Induced Plasticity (TWIP) Steels

“…Particularly in TWIP steels, mechanical twins are formed during deformation, and prevent the dislocation movement as they play a role in refining grains, which is known to be Hall-Petch effect. [1][2][3][4][5][6] Since the necking is also suppressed because of high work hardening rate, TWIP steels show high strength and ductility simultaneously. [6][7][8][9] In general, a considerable amount (about 20 wt pct) of Mn is contained in TWIP steels composed of austenite.…”

Effects of Annealing Temperature on Microstructure and Tensile Properties in Ferritic Lightweight Steels

“…The reduction in a vehicle's weight has been focused on in order to increase fuel efficiency and to decrease CO 2 emissions, which could have economic advantages and be eco-friendly in the research area of automotive steel sheets. [1][2][3][4][5][6][7][8][9] Recently, ferritic lightweight steels, in which Mn content decreases (to below 10 wt pct) and Al content increases, have been noted. This increase in Al content to 6 wt pct, for example, could possibly lead to a 10 wt pct reduction in automotive components.…”