Temperature dependence of tensile deformation behavior and strain hardening of lean duplex stainless steels

The effects of grain refinement on the resistance to pitting corrosion and passive film properties of lean duplex stainless steel (Fe–18.28Cr–5.68Mn–2.38Mo–0.39W–0.30N–0.035C, wt%) are studied. For this purpose, the grain size of this alloy is adjusted to 3, 7, and 17 μm through an annealing process after cold rolling. The pitting corrosion resistance is evaluated through potentiodynamic polarization tests in aqueous solutions containing Cl−. The grain size reduction enhances the resistance to pitting corrosion of the alloy. Mott–Schottky analysis and X‐Ray photoelectron spectroscopy analysis on the passive films show that, as the grain size decreases, the density of point defects of the film decreases, the film thickness increases, and the cation fraction of Cr of the film increases. The improved resistance to pitting corrosion by grain refinement is attributed to the formation of the thick and dense passive film with a high Cr content.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Grain Size on the Pitting Corrosion Resistance of Lean Duplex Stainless Steel

Lee

Park

et al. 2022

Effect of Interlayer Cooling Time on Microstructure and Properties of 2205 Duplex Stainless Steel Made by Cold Metal Transfer

Ou,

Xue,

Shen

et al. 2024

By adjusting the parameters in the additive manufacturing process, the optimization of the microstructure and mechanical properties of 2205 duplex stainless steel (DSS) is of great significance to ensure the reliability of the material in harsh environments. The 2205 DSS samples are prepared by cold metal transfer conditions of interlayer cooling time of 0, 30, 60, and 120 s, respectively, and the microstructure and properties of the samples are characterized in detail. With the increase of cooling time, the height of the samples increases, and the width decreases, and no defects are found in all the samples. It also reduces the grain size and contributes to the uniform distribution of grains. With the extension of cooling time, the proportion of austenitic phase gradually increases from 41.60% to 47.36%, while the proportion of ferrite decreases correspondingly. The mechanical properties of the samples are tested. With the increase of cooling time, the hardness of the samples increases from 646.32(±1.46) to 679.36(±7.27) MPa, and the ductility decreases from 60.10(±0.50)% to 43.67(±2.10)%. The results show that the interlayer cooling time can be used to regulate the formation, microstructure, and properties of DSS.

Strain Rate Sensitivity of Low‐Temperature Superplastic Heterogeneous Medium‐Mn Steel Fabricated by a Novel High‐Ratio Differential Speed Rolling

Pan,

Wang,

Zhang

et al. 2024

In the present article, insights into the high‐temperature deformation behavior of medium‐Mn steel (MMS), which is prepared via high‐ratio differential speed rolling (HRDSR), are provided. Moreover, through innovative bidirectional jump experiments, variations in the strain rate sensitivity index m under various conditions are obtained. In the research findings, it is indicated that an increase in strain rate (SR) leads to a hardening of the alloy. During high‐temperature deformation, the value of m decreases with the increase in SR, but the rate of decrease gradually slows down. Furthermore, the higher the temperature (T), the greater the impact of changes in SR on m. In addition, the change in deformation mechanism during deformation leads to microstructural changes, and under the main deformation mechanism of grain‐boundary sliding, m generally increases with strain. Interestingly, at a T of 760 °C, the material exhibits a strong texture with high orientation, resulting in larger m values and superior superplasticity (≈691%). This study not only enriches the research content of HRDSR but also has significant implications for the superplasticity research of MMS. Moreover, a reference is provided for the research of other superplastic materials.