Micro-electrochemical insights into pit initiation site on aged UNS S32750 super duplex stainless steel

Abstract

An aging treatment of UNS S32750 super duplex stainless steel at 1173 K for 1.0 ks produced σ and secondary austenite (γ2) phases in the α and γ phase boundary regions. Small amount of Mn-Cr oxide and MnS complex inclusions were present in the steel. No pitting was observed during the potentiodynamic polarization of a small area (200 × 200 µm) without inclusions in 1 M MgCl2 at 348 K. Because the electrode area included α, γ, σ, and γ2 phases, these phases and their boundaries alone could not act as initiation sites for pitting. The electrode area size was gradually reduced from 3 × 3 mm to 1 × 1 mm, and pitting corrosion was observed to occur at the Mn-Cr oxide and MnS complex inclusions in a region that appeared to be the γ2 phase near the σ phase.

Sigma Phase Effect on Pitting Corrosion of Super Duplex Stainless Steel UNS S32750

“…Amatsuka et al explain that formation clamp corrosion started with mechanism initiation that has connection with the ratio of the heat input is . (Amatsuka et al, 2023) Influence ratio heat input cold pass is divided heat input root pass against percentage sigma phase. Found in results chart that test coupons (TC) with percentage sigma phase highest as big 13.96% got from comparison ratio HI cold pass : HI root pass with mark percentage the ratio is 74%.…”

“…Increasing drilling volume of oil and gas from well free offshore platform and deepwater wells, will increase fabrication several materials, among others manifold and spools (Amatsuka et al, 2023) (Arun et al, 2019). material Which used For make modern equipment This must distinguished with enhancement productivity in condition corrosion And pressure Which high , For ensure operation safe and free from problem (Olsson & Snis, 2007).…”

Effect of Secondary Phase on Passivation Layer of Super Duplex Stainless Steel UNS S 32750: Advanced Safety of Li-Ion Battery Case Materials

“…Nillson focused on the corrosion resistance of UNS S 32750 with respect to heat-treatment temperatures and analyzed the corrosion resistance after the precipitation of secondary phases [ 29 ]. Similarly, Amatsuka analyzed the phase-fraction changes and corrosion resistance of UNS S 32750 based on heat-treatment temperatures and chemical compositions by employing corrosion-resistance analysis based on the volume fractions of phase [ 31 ]. Martins analyzed the microstructure of cast UNS S 32750.…”

Electrochemical Surface Modification of Al₈Co₁₉Cr₂₃Fe₃₂Ni₁₈ in H₂SO₄: A High-Entropy Alloy with High Pitting Corrosion Resistance and High Oxidation Resistance

“…1) Therefore, several studies on corrosion prevention have been conducted considering various aspects such as alloying elements, microstructures, heat treatments, coatings, and inhibitors. [2][3][4][5][6][7][8][9][10][11] High-entropy alloys (HEAs) have attracted the attention of many scientists and engineers as a promising concept for corrosion-resistant alloy design. [12][13][14][15] HEAs are typically composed of five or more elements with elemental concentrations varying from 5 to 35 at%.…”