Effects of Static Recrystallization and Precipitation on Mechanical Properties of 00Cr12 Ferritic Stainless Steel

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Effects of Static Recrystallization and Precipitation on Mechanical Properties of 00Cr12 Ferritic Stainless Steel YI SHAO, CHENXI LIU, TENGXIAO YUE, YONGCHANG LIU, ZESHENG YAN, and HUIJUN LI The 00Cr12 ferritic stainless steel samples were isothermally held at diﬀerent temperatures in the range of 700 C to 1000 C to investigate the eﬀect of static recrystallization and precipitation on mechanical properties, such as microhardness, tensile strength, and yield strength. The results show that the formation of the ﬁne recrystallized grain, as well as precipitation, coarsening, and dissolution of the second-phase particles, inﬂuences the mechanical properties remarkably. The ﬁne recrystallized grain can provide a positive grain boundary-strengthening eﬀect in the sample under a relatively high holding temperature. Coarsening and dissolution of M23C6 result in partial depletion of precipitate hardening. In contrast, the size and number density of MX particles are almost constant, regardless of the holding temperature; therefore, it can provide a better precipitation-hardening eﬀect. https://doi.org/10.1007/s11663-018-1273-0 The Minerals, Metals & Materials Society and ASM International 2018

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INTRODUCTION

IN recent years, ferritic stainless steels have been more increasingly used in such applications as the automotive and locomotive sectors, construction structures, and nuclear ﬁssion power plant components due to their outstanding resistance to corrosion, excellent strength and toughness, high-temperature performance, and good formability.[1–4] Furthermore, ferritic stainless steels have lower economic costs than austenitic and duplex stainless steels because of their low nickel contents. To obtain the full ferritic structure, 10.5 ~ 30 wt pct Cr has to be added, and the austenite-forming elements as C, N, and Ni are strictly controlled at a low level.[5–7] The microstructure at room temperature of ferritic stainless steels is the fully ferritic phase with body-centered-cubic crystal structure,[8] although a small amount of austenite may form at the elevated temperature region.[9,10] Rolling is a common technique for ferritic stainless steels. During rolling, the elongated grain forms and the anisotropy of microstructure and mechanical properties occur.[11–13] Recrystallization YI SHAO, CHENXI LIU, TENGXIAO YUE, YONGCHANG LIU, ZESHENG YAN, and HUIJUN LI are with the State Key Laboratory of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University, Tianjin 300354, P.R. China. Contact e-mail: [email protected] Manuscript submitted September 5, 2017.

METALLURGICAL AND MATERIALS TRANSACTIONS B

annealing is usually used to obtain the ﬁne equiaxed grains in order to acquire the desirable mechanical properties.[14–16] Annealing leads to the formation of some amounts of second-phase particles, such as M23C6, MX, M7C3, and Laves phase, which would provide the favorable precipitation-hardening eﬀect.[17–19] However, the eﬀects of recrystallization and precipitation on mech

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