Abstract
Pickling behaviour of the oxide layer on hot‐rolled 2205 duplex stainless steel (DSS) was studied in H2SO4 solutions with electrolytic workstation. The pickling rate at 75°C increases slightly with the H2SO4 concentration from 100 to 250 g L−1 but increases markedly as the concentration is higher than 250 g L−1. The solution temperature greatly accelerates the pickling rate. Fe3+ ion is an effective oxidant, which shows stronger inhibitive effect. The rotating disk electrode was used to simulate the moving state of steel strips in practice. The movement with the speed from 0 to 20 m min−1 results in weak acceleration effect on the pickling process. Under dynamic conditions, the pickling rate increases noticeably with changing the pulse current density from 0 to 0.2 A cm−2. The industrial pickling efficiency of 2205 DSS hot‐rolled strips increases from 5–8 m/min to 15–18 m/min. The surface quality is improved.
Highlights
Type 2205 duplex stainless steel (DSS) has been used widely in many industries for its excellent mechanical properties and corrosion resistance [1,2,3,4,5,6]
A specimen fixed on the rotating disk with a diameter of 15 cm was used as the working electrode, a platinum sheet as the counterelectrode, and Hg/Hg2SO4 as the reference electrode. e analytically pure H2SO4, ferrous sulfate, iron sulfate, and deionized water were used to prepare the electrolytes. e pickling processes were performed with a Princeton potentiostat (PAR 273A)
Electrochemical Measurement. e corrosion potential and electrochemical impedance spectroscopy (EIS) of the test specimens were measured during the pickling process with a Princeton potentiostat (VMP3)
Summary
Type 2205 duplex stainless steel (DSS) has been used widely in many industries for its excellent mechanical properties and corrosion resistance [1,2,3,4,5,6]. Erefore, the pickling of 2205 DSS hot-rolled strips is more difficult than that of standard austenitic grades [10]. E pickling process of stainless steels is used to remove the oxide scales and chromium depleted layer in order to restore the corrosion resistance and ensure the surface finish [11, 12]. Prepickling plays a critical role in the industrial production process of 2205 DSS hot-rolled strips. E pickling technology and mechanism are well known for the austenitic and ferritic stainless steels in the literature, but there are few systematical reports focused on the pickling for duplex stainless steel, especially for DSS 2205 hot-rolled strips. The pickling behaviour of the 2205 DSS hot-rolled strip in H2SO4 electrolytes under both static and dynamic conditions was investigated. The pickling behaviour of the 2205 DSS hot-rolled strip in H2SO4 electrolytes under both static and dynamic conditions was investigated. e pickling mechanism was discussed on the basis of mass loss and surface analysis
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