Effects of Sn and Sb on the Hot Ductility of Nb+Ti Microalloyed Steels

Chunyu He,Jianguang Wang,Wei Yu,Yulai Chen,Di Tang

doi:10.3390/met10121679

Abstract

Referencing the composition of a typical Nb+Ti microalloyed steel (Q345B), two kinds of steels, one microalloyed with Sn and Sb, and the other one only microalloyed with Sb were designed to study the effects of Sn and Sb on the hot ductility of Nb+Ti microalloyed steels. The Gleeble-3500 tester was adopted to determine the high-temperature mechanical properties of the two test steels. Fracture morphologies, microstructures and interior precipitation status were analyzed by SEM, CLSM (Confocal laser scanning microscope) and EDS, respectively. Results revealed that within the range of 950–650 °C, there existed the ductility trough for the two steels, which were mainly attributed to the precipitation of TiN and Nb (C, N). Additionally, precipitation of Sn and Sb were not observed in this research and the hot ductility was not affected by the addition of Sn and Sb, as compared with the Nb+Ti microalloyed steel. Therefore, addition of a small amount of Sn and Sb (≤0.05 wt.%) to the Nb+Ti microalloyed steel is favorable due to the improvement on corrosion resistance.

Highlights

Hot ductility metal materials can have a great impact on continuous casting, rolling, and other processes
According to extensive previous reports, hot ductility curves of microalloyed steels obtained by the high-temperature tensile tests have obvious ductility troughs, and brittle regions occur at about 700–1000 ◦ C [8,11,12]
For steels containing Ti and Nb, Xie, You et al [13] believed that fine Ti, Nb (C, N) particles can be precipitated near the austenite grain boundary at temperatures above 1000 ◦ C, and the precipitates may always exist stably

Summary

Introduction

Hot ductility metal materials can have a great impact on continuous casting, rolling, and other processes. For steels containing Ti and Nb, Xie, You et al [13] believed that fine Ti, Nb (C, N) particles can be precipitated near the austenite grain boundary at temperatures above 1000 ◦ C, and the precipitates may always exist stably. These fine precipitates pinned the grain boundaries and prevented the occurrence of dynamic recrystallization [9,14,15], which reduced the ductility of the steels . SooHoon, et al [19] found that SnO2 and

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