Role of Martensite Structural Characteristics on Corrosion Features in Ni-Advanced Dual-Phase Low-Alloy Steels
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Role of Martensite Structural Characteristics on Corrosion Features in Ni‑Advanced Dual‑Phase Low‑Alloy Steels Chao Hai1 · Xuequn Cheng1 · Cuiwei Du1 · Xiaogang Li1 Received: 24 March 2020 / Revised: 28 May 2020 / Accepted: 27 July 2020 © The Chinese Society for Metals (CSM) and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The relationship between the corrosion resistance and martensite structure of Ni-advanced dual-phase weathering steel was studied using transmission electron microscopy, scanning electron microscopy, electrochemical analysis, and atomic force microscopy. The investigations indicate that the final microstructure of the dual-phase weathering steel was composed of a large amount of low-carbon lath martensite distributed in the ferrite matrix. The potential of the martensite phase is higher than that of ferrite, which acts as a microcathode. As the martensite volume fraction in the Ni-advanced dual-phase weathering steel increased, the corrosion rate increased owing to the greater galvanic couple formed between the ferrite and martensite from the increasing ratio of the cathode area to the anode area. In addition, this work provides a method to obtain advanced weathering steel with improved mechanical properties and corrosion resistance. Keywords Weathering steel · Corrosion · Martensite · Dual phase · Galvanic couple
1 Introduction Weathering steels (WSs) are classified as low-carbon steels and are mainly alloyed with Cu, P, Cr, and Ni in a total proportion of less than 3–5 wt% [1–4]. Ni is specifically introduced into WS to develop Ni-advanced WSs, which are widely used in coastal structures [5–9]. At present, research on the atmospheric corrosion resistance of WSs has focused on the effect of alloying elements and grain size [2, 5, 7, 10]. Cheng et al. [5] investigated the effect of Ni on the corrosion resistance of WSs in acidic atmospheres. They found that 3.5 wt% is the optimum Ni concentration in WSs to enhance their atmospheric corrosion resistance. However, the effect of the microstructure on the corrosion resistance is still unclear. Dual-phase (DP) steels have attracted considerable research [11–16] for their interesting combination of high strength, good formability, continuous yielding, and low yield stress to tensile strength ratio, which have broad Available online at https://link.springer.com/journal/40195 * Xuequn Cheng [email protected] 1
Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
application prospects in the automotive industry. Lan et al. [13] developed DP steel through intercritical annealing of cold-rolled martensite. In this case, the fine ferrite grain size as well as uniform distribution of the martensite enhanced the work hardening, showing an improved strength-ductility balance. DP steels are generally produced by an intercritical heat treatment, and their microstructures mainly consist of hard martensite particles dispersed in a soft ductile ferrite matrix [17,
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