Effect of solution annealing on the microstructure evolution and corrosion behavior of 2205 duplex stainless steel

Abstract

The effects of solution annealing temperature and isothermal time on the phase composition evolution and corrosion behavior were investigated by employing energy dispersive spectrometry, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, and Mott–Schottky analysis. The pit morphologies were observed by a digital VHX‐5000 with a visible 3D microscopy system. The highest corrosion resistance and most stable passive films were obtained for specimen solution annealing at 1075 °C. Additionally, the solution time had a significant influence on the microstructure evolution and corrosion resistance of the duplex stainless steel. The largest impedance values were exhibited, revealing the best stability with a superior corrosion resistance of the films. The depth and size of pits that occurred on austenite were smaller than those on ferrite. The phase proportion on the microstructure and redistribution of the alloying elements caused by duplex interdiffusion solution annealing simultaneously affected the density of defects and the stability of the passive film, which determined the corrosion resistance. However, the semiconductor properties of the passive films were not affected.

Influence of Homogenization and Annealing Temperatures on the Microstructure, Mechanical Properties, and Passive Properties of Cold Rolled 2205 Duplex Stainless Steel

“…The increase in annealing temperature from 900 °C to 1100 °C decreases the corrosion resistance in this case. According to Zhang et al 12 , the increasing annealing temperatures increased the ferrite content and diluted the key alloying elements in the ferrite, lowering the corrosion resistance. However, it can be noticed in Figure 14b an increase in δ increasing annealing temperature for FP1, FP2, and FP3 samples indicating a formation of a thicker passive film.…”

“…In addition to the chemical composition, an annealing treatment is another important factor influencing the corrosion resistance of DSS 10,12 . With the given chemical composition, varying heat treatment temperatures can change the proportion of the ferrite and austenite phases and adjust the redistribution of alloying elements in the two phases, leading to a variation in the corrosion resistance of each one 11,12 .…”

“…During the last few years, the effects of rolling, solution annealing, and annealing temperatures on the microstructural features and corrosion resistance of DSS have been intensively investigated 12,13,[17][18][19][20][21][22][23] . Mondal et al 13 reported a decrease in corrosion resistance after grain coarsening during solution annealing of a super duplex stainless steel at 1050°C for different times.…”

“…Mondal et al 13 reported a decrease in corrosion resistance after grain coarsening during solution annealing of a super duplex stainless steel at 1050°C for different times. According to Zhang et al 12 annealing a hot rolled 2205 DSS from 975 to 1075 °C for 2h the leads to a more homogeneous microstructure, and the pitting corrosion resistance increases. Malta et al 24 .…”

Micro‐galvanic corrosion of duplex stainless steel annealed at different temperatures evaluated by experiments and a numerical simulation model

“…With the increase in the annealing temperature, the volume fraction of the α phase gradually increased, while that of the γ phase gradually decreased, owing to the phase transformation and element migration from phases with higher chemical potentials to phases with lower chemical potentials with the increase in the annealing temperature. [37][38][39] Six points of each phase of the DSSs annealed at different temperatures were randomly selected to measure the chemical composition through SEM-EDS. The average values with errors of each phase of the DSS are shown in Figure 5.…”