Influence Of Flow Velocity On Erosion-Corrosion Performance Of 90º Carbon Steel Elbows In Potash Brine

In this study, the effects of flow velocity and solid concentration on erosion-corrosion behavior of AISI 1018 long-radius steel elbows (Schedule 40) in saturated potash brine were investigated. Potash brine containing 10 and 30 wt% of silica sands flowing at 2.5, 3.0, 3.5 and 4.0 m/s through a continuous loop with pipe internal diameter of 2.54 cm was used as the slurry. All experiments were conducted at 30 ºC. The surface damage on elbows was evaluated using scanning electron microscopy (SEM). It was found that material loss per unit area was greater at high slurry velocity and solid concentration. Corrosion pits were visible on the elbow surfaces at low slurry velocities, but pits were not formed at higher velocities. Mechanical damage was concluded to b

Erosion-corrosion of carbon steel and duplex stainless steel elbows in potash brine-sand slurry

Carbon and low alloy steel pipes are widely used to transport slurries in the mining and mineral processing industry because of their good mechanical properties and relative affordability. However, the exposed internal walls of these pipes are prone to erosion-corrosion damage, which can lead to product leakage and eventual failure of the piping system. The purpose of this research is to evaluate the performance of AISI 1018 carbon steel and AISI 2205 duplex stainless steel elbows to erosion-corrosion damage in a saturated potash brine-sand slurry. Erosion-corrosion tests were conducted in a flow loop using a slurry consisting of saturated potash brine-sand slurry. Flow velocity and particle concentration were varied, but the slurry temperature was kept constant at 30 ± 1 °C. The synergistic effect of corrosion and erosion during erosion-corrosion was evaluated by conducting corrosion and erosion tests using particle-free saturated potash brine and deaerated slurry, respectively. The elbow surfaces before and after exposure to different test conditions were characterized using a scanning electron microscope, optical profilometer, Vickers micro-hardness tester, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, and electron-backscattered diffraction. The results of these study revealed that the synergy between corrosion and erosion accelerated erosion-corrosion rates for the exposed carbon steel elbows. Microstructural examination showed that mechanical wear, in conjunction with pitting corrosion, played a substantial role in removing materials from the exposed surfaces of carbon steel elbows, especially at low slurry flow velocity. Raman and X-ray spectroscopic studies indicated that the corrosion products found inside the pits of the exposed carbon steel elbow are FeOOH, Fe2O3 and Fe3O4. This confirms the oxidation of iron during erosion-corrosion in saturated potash brine slurry. Furthermore, mechanical wear was the sole material removal mechanism for the duplex stainless steel elbows, which indicate that the combined effects of corrosion and erosion did not influence erosion-corrosion rates. X-ray and electron-backscattered diffraction techniques revealed that some austenite phase of the duplex stainless steel transformed to martensite after particle impacts at high velocity. The exceptionally high hardness and brittleness of martensite accelerated the removal of materials from the duplex stainless steel surface by brittle chipping. Plastic deformation due to particle impingement occurred up to about 4 μm below the exposed elbow surface

Influence of delta ferrite on corrosion susceptibility of AISI 304 austenitic stainless steel

In the current study, the influence of delta (δ) ferrite on the corrosion susceptibility of AISI 304 austenitic stainless steel was evaluated in 1Molar concentration of sulphuric acid (H2SO4) and 1Molar concentration of sodium chloride (NaCl). The study was performed at ambient temperature using electrochemical technique—Tafel plots to evaluate the corrosive tendencies of the austenitic stainless steel sample. The as-received (stainless steel) specimen and 60% cold-worked (stainless steel) specimens were isothermally annealed at 1,100°C for 2 h and 1 h, respectively, and quenched in water. The results obtained show that the heat-treated specimen and the 60% cold-worked plus heat-treated specimen exhibited higher corrosion susceptibility than the as-received specimen, which invariably contained the highest fraction of δ ferrite particles. The finding shows that the presence of δ ferrite, in which chromium (Cr), the main corrosion inhibitor segregates, does not degrade and or reduces the resistance to aqueous corrosion of the austenitic stainless steel material

Influence of delta ferrite on corrosion susceptibility of AISI 304 austenitic stainless steel PUBLIC INTEREST STATEMENT

Abstract: In the current study, the influence of delta (δ) ferrite on the corrosion susceptibility of AISI 304 austenitic stainless steel was evaluated in 1Molar concentration of sulphuric acid (H 2 SO 4 ) and 1Molar concentration of sodium chloride (NaCl). The study was performed at ambient temperature using electrochemical technique-Tafel plots to evaluate the corrosive tendencies of the austenitic stainless steel sample. The as-received (stainless steel) specimen and 60% cold-worked (stainless steel) specimens were isothermally annealed at 1,100°C for 2 h and 1 h, respectively, and quenched in water. The results obtained show that the heat-treated specimen and the 60% cold-worked plus heat-treated specimen exhibited higher corrosion susceptibility than the as-received specimen, which invariably contained the highest fraction of δ ferrite particles. The finding shows that the presence of δ ferrite, in which chromium (Cr), the main corrosion inhibitor segregates, does not degrade and or reduces the resistance to aqueous corrosion of the austenitic stainless steel material. Osoba has specialized knowledge in engineering research, involving joining of materials and characterization of the joint properties, aside from skills in quality management, production planning, and process control. His current research focus is in the area of processing-microstructure-property relationship studies in aerospace and composite materials. Raheem and Ikenna are graduate students in the Department of Metallurgical and Materials Engineering. In this study, detailed experimental procedure with analysis was used to correlate the corrosion behavior with the observed microstructural features in the material to understand better, the influence of delta ferrite on Corrosion Susceptibility of Stainless Steel. PUBLIC INTEREST STATEMENT Rust resistance metals such as the popular stainless steel often contain some quantities of delta (δ) ferrite that has been previously reported to lower its strength and ability to withstand repeated load application. This work investigated the role of the delta (δ) ferrite on corrosion susceptibility of stainless steel in sulphuric acid (H 2 SO 4 ) and sodium chloride (NaCl) environment. The results of the study show that the amount of δ-ferrite in a matrix in which chromium (Cr), the main corrosion resistance enabling element dominates, does not reduce or compromise significantly, the rust resistance properties of the stainless steel materials