Study on High-Temperature Mechanical Properties of Fe–Mn–C–Al TWIP/TRIP Steel

Abstract

In this study, high-temperature tensile tests were carried out on a Gleeble-3500 thermal simulator under a strain rate of ε = 1 × 10−3 s−1 in the temperature range of 600–1310 °C. The hot deformation process of Fe–15.3Mn–0.58C–2.3Al TWIP/TRIP at different temperatures was studied. In the whole tested temperature range, the reduction of area ranged from 47.3 to 89.4% and reached the maximum value of 89.4% at 1275 °C. Assuming that 60% reduction of area is relative ductility trough, the high-temperature ductility trough was from 1275 °C to the melting point temperature, the medium-temperature ductility trough was 1000–1250 °C, and the low-temperature ductility trough was around 600 °C. The phase transformation process of the steel was analyzed by Thermo-Calc thermodynamics software. It was found that ferrite transformation occurred at 646 °C, and the austenite was softened by a small amount of ferrite, resulting in the reduction of thermoplastic and formation of the low-temperature ductility trough. However, the small difference in thermoplasticity in the low-temperature ductility trough was attributed to the small amount of ferrite and the low transformation temperature of ferrite. The tensile fracture at different temperatures was characterized by means of optical microscopy and scanning electron microscopy. It was found that there were Al2O3, AlN, MnO, and MnS(Se) impurities in the fracture. The abnormal points of thermoplasticity showed that the inclusions had a significant effect on the high-temperature mechanical properties. The results of EBSD local orientation difference analysis showed that the temperature range with good plasticity was around 1275 °C. Under large deformation extent, the phase difference in the internal position of the grain was larger than that in the grain boundary. The defect density in the grain was large, and the high dislocation density was the main deformation mechanism in the high-temperature tensile process.

Susceptibility of High-Manganese Steel to High-Temperature Cracking

“…Yang et al [29] obtained similar results. The high-temperature tensile tests were carried out on a Gleeble-3500 thermal simulator in the temperature range of 600-1310 • C. The high-manganese Fe-Mn-C-Al TWIP/TRIP steel at different temperatures was studied.…”

Interface Strengthening and Toughening Mechanism of Hot Rolled Multilayer TWIP/40Si2CrMo Steels

“…It can be seen that the interface of all multilayer steels mainly forms the oxide of Al, indicating that the Al oxidation cannot be completely avoided in multilayer TWIP/40Si2CrMo steel under the condition of 10 −2 Pa vacuum degrees. When the multilayer steel was in the heating process, the active Al in TWIP steel was easy to react with oxygen in the air to form Al 2 O 3 [20]. When the hot rolling reduction was 80%, the interfacial oxides of the multilayer steel were larger in size and quantity.…”

Effects of Si on the Ductile‐to‐Brittle Transition Behavior of As‐Cast Advanced High‐Strength Steels

“…There is a sizable body of literature concerning mechanisms of cracking at as‐cast slabs at high temperature, above 700 °C. [ 13–21 ] Cooling cracks are also known to occur in as‐cast slabs at lower temperatures, below 300 °C, espacially in higher‐Si grades. The mechanism for this low‐temperature cracking in high‐Si as‐cast slabs is not fully understood.…”