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Vanadium-induced high-temperature oxidation deterioration mechanism of 019Cr18CuNb ferritic stainless steel

Jie ShengSchool of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, ChinaQianying LinSchool of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, ChinaAkbar PushanovAlmalyk State Technical Institute, Almalyk 110100, UzbekistanZikun YangSchool of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, ChinaYufeng LiState Key Laboratory of Advanced Processing and Recycling of Nonferrous Metal, Lanzhou University of Technology, Lanzhou 730050, ChinaXingchang TangSchool of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, ChinaYang GaoSchool of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, ChinaYang HuiJiayuguan Productivity Promotion Center, Jiayuguan 735100, ChinaDanni YangJiuquan Iron and Steel (Group) Co., Ltd., Jiayuguan 735100, ChinaXuefeng LuSchool of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China

2026en

ABI

Annotatsiya

ABSTRACT The dual conflicting effects of vanadium (V) on room-temperature mechanical performance and high-temperature oxidation resistance of 019Cr18CuNb ferritic stainless steel (FSS) were investigated. Three steels with 0, 0.2 and 0.3 wt% V were smelted into unified hot-rolled annealed sheets. Room-temperature tensile, Charpy impact and hardness tests were conducted on specimens cut from the same production batch. Isothermal oxidation tests at 700-900 °C for up to 125 h were performed on separate specimens from the identical batch to exclude interference from high-temperature exposure. Oxidation kinetics obeyed Wagner’s parabolic law during the steady 50-125 h stage, with both oxidation mass gain and parabolic rate constant K p increasing monotonically with rising V content and temperature. The V-free alloy formed a smooth, dense triple-layer oxide scale comprising an inner Cr 2 O 3 barrier, an intermediate MnCr 2 O 4 spinel and an outer Fe 2 O 3 layer. TEM characterization revealed that V preferentially binds interstitial N, releasing solute Nb that subsequently reacts with Cr 2 O 3 at the oxide-substrate interface to form brittle CrNbO 4 . Concurrently, low-melting V 2 O 5 formed at all test temperatures, infiltrating oxide boundaries and microdefects to disrupt the integrity of Cr 2 O 3 . V exhibited dual functionality, where moderate addition enhances strength and toughness via grain refinement and nano-(Nb,V)(C,N) precipitation, while excessive V severely degraded oxidation resistance via a previously unreported synergistic pathway coupling V-N competitive precipitation and interfacial CrNbO 4 formation. This work provides a theoretical basis for optimization of Nb-stabilized medium-chromium FSS.

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DOI: 10.1016/j.jmrt.2026.08.175

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