Hot Ductility and Compression Deformation Behavior of TRIP980 at Elevated Temperatures
- PDF / 2,903,557 Bytes
- 12 Pages / 593.972 x 792 pts Page_size
- 11 Downloads / 218 Views
Hot Ductility and Compression Deformation Behavior of TRIP980 at Elevated Temperatures MEI ZHANG, HAIYANG LI, BIN GAN, XUE ZHAO, YI YAO, and LI WANG The hot ductility tests of a kind of 980 MPa class Fe-0.31C (wt pct) TRIP steel (TRIP980) with the addition of Ti/V/Nb were conducted on a Gleeble-3500 thermomechanical simulator in the temperatures ranging from 873 K to 1573 K (600 °C to 1300 °C) at a constant strain rate of 0.001 s1. It is found that the hot ductility trough ranges from 873 K to 1123 K (600 °C to 850 °C). The recommended straightening temperatures are from 1173 K to 1523 K (900 °C to 1250 °C). The isothermal hot compression deformation behavior was also studied by means of Gleeble-3500 in the temperatures ranging from 1173 K to 1373 K (900 °C to 1100 °C) at strain rates ranging from 0.01 s1 to 10 s1. The results show that the peak stress decreases with the increasing temperature and the decreasing strain rate. The deformation activation energy of the test steel is 436.7 kJ/mol. The hot deformation equation of the steel has been established, and the processing maps have been developed on the basis of experimental data and the principle of dynamic materials model (DMM). By analyzing the processing maps of strains of 0.5, 0.7, and 0.9, it is found that dynamic recrystallization occurs in the peak power dissipation efficiency domain, which is the optimal area of hot working. Finally, the factors influencing hot ductility and thermal activation energy of the test steel were investigated by means of microscopic analysis. It indicates that the additional microalloying elements play important roles both in the loss of hot ductility and in the enormous increase of deformation activation energy for the TRIP980 steel. DOI: 10.1007/s11663-017-0974-0 Ó The Minerals, Metals & Materials Society and ASM International 2017
I.
INTRODUCTION
CONTINUOUS casting (CC) is a rapidly developing advanced casting technology due to its low cost, energy saving, and high efficiency. However, cracks are prone to form during CC if process is unreasonable. There are three typical embrittlement zones for carbon steels in the temperatures ranging from 873 K (600 °C) to Tm.[1,2] The embrittlement zone is quite different for various steels. It was reported that the formations of pro-eutectoid ferrite film and the precipitation of V, Nb, or Al at austenite grain boundaries play important roles in the loss of hot ductility.[3–6] Mintz et al.[7] found that reducing the C (lower than the peritectic C range) and N levels brings better ductility in Nb-containing steels because it limits the amount of Nb(CN) precipitation. Kyung Chul Cho[8]
MEI ZHANG is with the School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China and also with State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072, China. Contact e-mail: [email protected] HAIYANG LI, BIN GAN, XUE ZHAO, and YI YAO are with the School of Materials Science and Engineering, Shanghai University. LI WANG is with the State Key La
Data Loading...
