Effect of Austenitization Conditions on the Transformation Behavior of Low Carbon Steel Containing Ti–Ca Oxide Particles
The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China
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Materials 2019, 12(7), 1070; https://doi.org/10.3390/ma12071070
Received: 26 February 2019 / Revised: 23 March 2019 / Accepted: 27 March 2019 / Published: 1 April 2019
(This article belongs to the Section Structure Analysis and Characterization)
Inclusion-induced acicular ferrite (AF) nucleation has been used for microstructure refinement in steel. Austenitization conditions have a significant influence on AF nucleation ability. In this paper, the effects of austenitization temperature and holding time on the transformation behaviors of low carbon steel containing Ti–Ca oxide particles were studied. A thermal treatment experiment, high temperature in situ observation, and calculation of Mn diffusion were carried out. The results indicate that small austenite grain size under low austenitizing temperature promoted grain boundary reaction products. With an increase in austenitizing temperature, the nucleation sites transferred to intragranular particles and AF transformation was improved. The inclusion particles in the Ti–Ca deoxidized steel were featured by an oxide core rich in Ti and a lesser amount of Ca and with MnS precipitation on the local surface, which showed a strong ability to promote AF nucleation. At a low austenitizing temperature, Mn diffusion was limited and the development of Mn-depleted zones (MDZs) around inclusions was not sufficient. The higher diffusion capacity of Mn at a high austenitizing temperature promoted the formation of MDZs to a larger degree and increased the AF nucleation ability. Boron segregation at large-sized austenite grain boundaries played an important role in AF transformation. Austenite grain size, Mn-depleted zone development, and boron segregation at grain boundaries were the decisive factors influencing the transformation behaviors under different austenitization conditions for the test steel.
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Keywords:
low carbon steel; austenitization; Ti–Ca oxide; acicular ferrite; Mn-depleted zone; boron segregation
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MDPI and ACS Style
Wang, C.; Wang, X.; Kang, J.; Yuan, G.; Wang, G. Effect of Austenitization Conditions on the Transformation Behavior of Low Carbon Steel Containing Ti–Ca Oxide Particles. Materials 2019, 12, 1070. https://doi.org/10.3390/ma12071070
AMA Style
Wang C, Wang X, Kang J, Yuan G, Wang G. Effect of Austenitization Conditions on the Transformation Behavior of Low Carbon Steel Containing Ti–Ca Oxide Particles. Materials. 2019; 12(7):1070. https://doi.org/10.3390/ma12071070
Chicago/Turabian StyleWang, Chao; Wang, Xin; Kang, Jian; Yuan, Guo; Wang, Guodong. 2019. "Effect of Austenitization Conditions on the Transformation Behavior of Low Carbon Steel Containing Ti–Ca Oxide Particles" Materials 12, no. 7: 1070. https://doi.org/10.3390/ma12071070
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