Corrosion Rate Of Specimens Research Articles

ANALISIS PENGARUH VARIASI HOLDING TIME ANNEALING TERHADAP LAJU KOROSI TITANIUM PADA LARUTAN CAIRAN TUBUH SINTETIS

Biomaterials are crucial for bone implants due to their biocompatible and inert nature, ensuring no adverse effects within the human body. Titanium is renowned for its exceptional corrosion resistance. This research aims to analyze the impact of annealing holding time and pH of synthetic body fluid on the hardness and corrosion rate of titanium. The annealing process was performed at 700°C, with holding times of 30, 60, and 90 minutes. As an electrolyte medium, a Hanks' solution with pH variations of 4, 6, and 8 was used and maintained at 37°C. Potentiodynamic corrosion testing demonstrated the lowest corrosion rate in specimens treated with 30 minutes of annealing at pH 8, measuring 0.32 x 10-2 mmpy. The 30-minute annealing exhibited the lowest corrosion rate, which was confirmed by Electrochemical Impedance Spectroscopy (EIS) results showing a higher Rp value, indicating a lower corrosion rate. This is attributed to the presence of a passive Rutile TiO2 layer formed during the annealing process, as confirmed by X-ray Diffraction (XRD) analysis. Metallography observations indicated that the microstructure of untreated specimens consisted of α and β phases. Scanning Electron Microscopy (SEM) analysis of specimens annealed for 30 minutes revealed an oxide layer on the surface without any visible pores. However, an increase in annealing holding time led to the formation of pores, particularly noticeable after 90 minutes of annealing. The presence of pores in the oxide layer resulted in an increased corrosion rate with longer annealing holding times. Conversely, hardness testing demonstrated that longer annealing holding times resulted in higher hardness values.

Effect of Flow on the Corrosion Behavior of Pipeline Steel in Supercritical CO2 Environments with Impurities

Corrosion is a major concern in transmission pipelines that transport captured CO2. While dry CO2 is noncorrosive, significant corrosion has been reported in dense-phase CO2 with trace amounts of water and impurities such as O2, H2S, SOx, and NOx. The aim of this work is to improve our understanding of the physicochemical aspects of the corrosion of carbon steels in the high-pressure environments associated with CO2 transmission pipelines. The effect of flow on the corrosion of X65 carbon steel was investigated in a series of autoclave tests with different combinations of impurity concentrations in supercritical CO2 conditions (8 MPa and 35°C). The corrosion rate of specimens was determined by weight loss measurements. The surface morphology and composition of the corrosion product layers were characterized using surface analytical techniques (scanning electron microscopy, eneregy dispersive x-ray spectroscopy, and Raman microscopy). Localized corrosion was measured via surface profilometry after corrosion products were removed. Results showed that no corrosion was observed in the supercritical CO2 with 650 ppmv of water, 50 ppmv SO2, and 100 ppmv NO, but corrosion occurred when SO2 concentration was increased to 4,500 ppmv and 40,000 ppmv of O2 was added to the system. The presence of flow significantly accelerated the corrosion of carbon steel. Furthermore, localized corrosion was observed in the presence of both O2 and flow.

Study on the Corrosion Behavior and Mechanism of ER8 Wheel Steel in Neutral NaCl Solution

This paper analyzed the corrosion behavior and corrosion performance of ER8 wheel steel through a full immersion test. The average corrosion rate of the ER8 wheel specimen in 2.0% NaCl solution shows a gradual increase over the whole corrosion cycle. Although the corrosion rate showed fluctuations at 3.5% and 5.0% concentration before 576 h, the corrosion rate also showed a steady increase after 576 h. The corrosion rates of specimens at different concentrations after 2160 h were over 0.12 mm/year. With increasing immersion times or concentrations of NaCl solution, the coverage area of the corrosion products dominated by iron oxides gradually increased, and the corrosion products on the surface became denser. The corrosion products were primarily γ-FeOOH, α-FeOOH and Fe3O4. As the density of the surface corrosion products increased, cracks and holes appeared on the surface of the rust layers, which made the rust layer unable to protect the substrate from further corrosion. After removing the corrosion products, pitting corrosion appeared on the surface of the substrate. The radius of the capacitive reactance arc gradually decreased with the increasing immersion time. The impedance modulus in the low-frequency region decreases and then increases with increasing NaCl solution concentration, which is the highest in 3.5% NaCl solution. Icorr increased with an increasing Cl− concentration, which was similar to the mechanism of catalytic electrolysis due to Cl−. The specimens with rust layers have worse corrosion resistance when the immersion time is extended. The corrosion product did not protect the substrate but accelerated the corrosion process.

Corrosion resistance of ultra-high performance fibre- reinforced concrete

The corrosion resistance of ultra-high performance concrete (UH) made with different fibre contents and under distinct curing conditions was studied. No signs of carbonation were observed after 1 year of accelerated carbonation testing (3% CO2). The fibreless UHs’ electrical resistivity was above 5000 Ω·m, although these values were 2-fold higher than a UH with 1% fibres and approximately 5-fold higher than a UH with 2% fibres. Concrete resistance to chloride penetration was also extremely high (the diffusion coefficient equalled 1.3·10−13 m2/s) and curing temperatures of 60 °C or 90 °C improved even more these properties, while lack of curing made them slightly worse. Given these excellent properties, the corrosion rate in specimens submerged in chloride solution for 1 year was negligible (iCORR from 0.007 to 0.025 µA/cm2). These values remained stable with time, unlike the 50 MPa concrete at 2 months when iCORR starting to increase and was 12-fold higher after 1 year. The time estimated for corrosion onset in UH is on average about 150-fold higher than that of 50 MPa.

ANALYSIS OF CORROSION RATE OF ASTM A 387 GRADE 12 AND A 283 GRADE FOR SULFURIC ACID TANK MATERIAL

Corrosion is a process of degradation metal quality which is very detrimental in the industry. Especially in an industries related to utilization of acidic liquids such assulfuric acid, hydrochloric acid, etc. If corrosion rate of carbon steel can be estimated, the prediction of remaining life of carbon steel, and the preventive methods of corrosionwould be more appropriate. This will reduce technical, economic and aesthetic losses. The aims of this study was to determine corrosion rate of carbon steel in sulfuric acid. This study used ASTM A 387 Grade 12 and ASTM A 283 Grade A carbon steel type fortank material, where one material is represented by 5 specimen. The corrosion rate of Specimens were measured by the weight loss method for 31 days. The 5 specimens were divided into 3 regions where specimens no.1 and 2 were immersed in sulfuric acid , specimens no.3 were in the middle area or zone level (partially immersed), and specimens no.4 and 5 were not immersed in sulfuric acid. The highst corrosion rate occured on specimen No.3 with maximum corrosion rate was 0,097 mm/y for ASTM A 387 Gr 12 and 0,096 mm/y untuk material ASTM A 283 Gr A. The results of corrosion rate on ASTM A 387 Grade 12 material are lower than corrosion rate of ASTM A 283 Grade A material. This is caused by presence of Mo and Cr alloy elements in ASTM A 387 Grade 12.

Corrosion Resistance Analysis of ST37 Carbon Steel Material Using Phosphate Conversion Coating in Various Immersion Durations

Conversion coating in metal material was a method to control the corrosion. It applied in parts of car, aircraft, factory installation, and other appliances. There were three types of conversion coating: phosphate conversion coating, chromate conversion coating, and oxalate conversion coating. There were several aspects to consider in controlling the corrosion fully. This research used phosphate because phosphate conversion coating had a low corrosion rate, affordable production cost, and environmentally friendly. This research aimed to find out the corrosion resistance of ST37 carbon steel using phosphate conversion coating in various immersion durations. Therefore, the result was a breakthrough in using phosphate conversion coating for the industries. This research used the weight loss method to calculate the corrosion rate and macro photos to obtain the corrosion form during the test. This research used ST37 carbon steel with 100 mm x 30 mm x 10 mm as the specimen and phosphate with various coating durations (10, 20, and 30 minutes). Each variation had three specimens, so this research had nine specimens in total. This research calculated the daily corrosion rate for seven days using 5% NaCl as the corrosion solution. The average corrosion rate in specimens with 10 minutes duration was 1.9599 mpy, specimens with 20 minutes immersion was 1.7647 mpy, whereas specimens with 30 minutes duration were 1.3287 mpy. Thus, the longer immersion duration created a smaller corrosion rate. Also, the corrosion formed during the test was pitting and uniform corrosion.

Microdefects of Biocorroded Pipe Steel Surfaces and Safety Assessment of Localized Stress Concentrators

The effect of sulfate-reducing bacteria (SRB) on the corrosion of steel 20 was investigated. Results demonstrated that the chemical composition of corrosion products, the corrosion rate, and corrosion type were altered due to the adherence of SRB and the subsequent formation of biofilm on the steel 20 surface. The micromechanisms of biocorrosion damage of specimens from pipe steel 20 were quantified on the basis of the microgeometry of the degraded surface and the localization parameters of corrosive stress microconcentrators. Stress concentrators in the vicinity of the micro-cuts, which are the depths of the profilograms, make it possible to evaluate safe (allowable) microcorrosion damage. The proposed approach complements the well-known methods for monitoring biodeterioration of pipe steels. With its help, it was found that a decrease in the corrosion rate of specimens with the addition of an inhibitor does not always clearly indicate its effectiveness. The case where the introduction of an inhibitor led to the destruction of the SRB biofilm on the surface of specimens from steel 20, but caused the activation of local corrosion processes and the formation of a more developed microrelief, is considered. The hollows of such microrelief are potential places of origin of defects, which require additional control.

The effects of Cl−and direct stray current on soil corrosion of three grounding grid materials

PurposeThe purpose of this paper is to study the effects of Cl−and direct stray current on the soil corrosion of three grounding grid materials.Design/methodology/approachThe electrochemical corrosion properties of three grounding grid materials, which include the Q235 steel, Q235 galvanized flat steel and copper, were measured by means of the weak polarization curve method and electrochemical impedance spectroscopy; the corrosion rate of specimens was calculated using the weight loss method; and the specimen surfaces were characterized using the scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis.FindingsResults showed that both factors, Cl−and direct stray current, can accelerate the corrosion rate of grounding grid materials. The magnitude of DC stray current density affected the mass transfer type and response frequency of the anode and cathode reaction of grounding materials, while the Cl−contents of the soil only affect the mass transfer rate of the electrode material from the electrochemical impedance spectroscopy diagrams. The electric field generated by the DC stray current caused Cl−directed migration. The larger the DC stray current density, the greater the diffusion process and the greater the weight loss rate of the grounding grid materials that would have a logarithmic relationship with the Cl−content at the same DC stray current density. The corrosion resistance of the three materials is copper > Q235 galvanized flat steel > Q235 flat steel.Originality/valueThe paper provides information regarding the relationship among Cl−, direct stray current and corrosion of three grounding grid materials by means of electrochemical impedance spectroscopy. Meanwhile the weight loss rate is the logarithmic relationship with the Cl−content, which is useful for understanding the corrosion mechanism of Q235 steel, Q235 galvanized flat steel and copper under the condition of Cl−and direct stray current in soil.

The corrosion behavior of ferrous materials immersed in acidic-media using D-optimal design

PurposeThe purpose of this paper is to model the corrosion rate behavior for two ferrous materials, carbon steel AISI 1020 and stainless steel AISI 304, immersed in ferric sulfate and ferric chloride solutions using D-optimal design with response surface methodology.Design/methodology/approachExperimental design addresses two factors (concentration and contact time) with multilevel categories, in order to predict and compare the corrosion rates of the studied materials immersed in flocculants solutions. A corrosion rate of specimens was calculated from mass loss determinations.FindingsThe authors used a polynomial model to fit the experimental values, thereby predicting significantly higher corrosion rates in ferric chloride solutions, as compared to ferric sulfate.Originality/valueThe authors propose a high fidelity model of the corrosion rate of each carbon steel and stainless steel material using D-optimal design with a response surface method (RSM).

Caffeine as A Natural Corrosion Inhibitor for Mild Steel in Nacl Solution

Corrosion inhibitors are substances that added to the environment in small concentration and can effectively reduce the corrosion rate that of a metal surface. Natural inhibitors are one types of inhibitor being researched as it brings less environmental impact on the environment. This research was focused on the application of caffeine as inhibitor for corrosion of mild steel in seawater condition. The objective of this project was to develop the relationship between caffeine concentration on the corrosion of mild carbon steel in both static and moving solution contained 3.5-wt% NaCl. Three types of solution were prepared, which are NaCl without addition of caffeine, NaCl with 1-wt% of caffeine and NaCl with 2-wt% of caffeine. Corrosion testing was carried out by weight loss measurement. The microstructures of corroded mild steel specimens were observed under optical microscope. The experimental results indicated that by adding caffeine into the environment medium, weight loss of mild steel specimen was reduced. The corrosion rate of specimens was decreased when more caffeine was added to the environment. From optical microscopic observation, caffeine performed its inhibition effect likely by forming a protective layer which acts as barrier to prevent further corrosion of mild steel in NaCl solution.

Corrosion behavior of two low alloy steel in simulative deep-sea environment coupling to titanium alloy

Corrosion behavior of two different low alloy steels (specimen 1, specimen 2) coupling to titanium (Ti) alloy was studied in simulative deep-sea environment with 500 m depths. Immersion tests revealed that the corrosion rate of specimen 1 was higher than that of specimen 2. The micro morphology showed all specimens of specimen 1 steel was susceptible to both intergranular and pitting corrosion. Electrochemical results imply that the galvanic current of specimen 1 was bigger than specimen 2, then decreased and stabilized at a small range after 15 h correspond. Finite element method was constructed to explain the development of the galvanic current density distribution with distance to the electrodes. The corrosion resistance of the alloy steels followed the order: specimen 2 > specimen 1 when coupling to Ti alloy.

Combined Effect of Base Metal Dilution and Thermal Aging Conditions on the Corrosion Performance of Stainless Steel Claddings

Objectives: Present work investigates the effects of base metal dilution and the thermal aging treatment on corrosion performance and strength of stainless steel claddings, fabricated by gas metal arc welding process. Methods/Statistical Analysis: Austenitic stainless steel AISI SS 316L was selected as the cladding material and low carbon steel as substrate for the present study. Experimental conditions were selected to achieve a varying degree of dilution of the deposit. Thermal aging treatment was given to specimens at 700oC for 2 hours, 4 hours and 20 hours. The specimens were subjected to Double Loop Electrochemical Potentio Kinetic Reactivation (DLEPR), boiling nitric acid, and microhardness testing. Findings: Microhardness results of the clad deposits showed a continuous decrease in values from top of clad deposit to the base metal. However there is almost constant values of microhardness observed when it was measured along the clad deposit. Moreover the deposits with high dilution showed low microhardness values than that of low dilution clad beads. The low dilution clad deposits also performed better on testing the corrosion rate and degree of sensitization as compared to high dilution deposits. Corrosion rate measured from boiling nitric acid test showed a significant growth with increase of thermal aging time due to carbide precipitation. The corrosion rate of specimens in the as clad condition was as low as 0.19 mm/month which increased to 3.64 mm/month when sensitized for 20 hours at 700oC. Degree of sensitization (DOS) calculated by DLEPR test is more significantly affected by the thermal aging treatment. The DOS values varied from as low as 2.47 % to high as 31% for as clad and sensitized conditions respectively. Application/Improvements: The present study can beneficially be adopted for weld overlay fabrications as it suggests the processing conditions to forecast the adequate strength and corrosion performance of components in similar service conditions.

Effect of Ferrous Ion on the Corrosion Behaviour of 410 Stainless Steel in Wet H<sub>2</sub>S Environment

In this paper, the effect of ferrous ion on the corrosion behavior of 410 martensitic stainless (410SS) steel was investigated by corrosion tests, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion tests were conducted in brine solution saturated with H2S and two type of iron compounds (FeS and FeSO4). The reults revealed that there exists apparent difference between piting resistence of FeSO4 and FeS addition for 410SS. The corrosion rates of specimens in FeSO4 solution was much higher than that of FeS, and the corrosion rate reached a maximum of 1.299 mm/year when the concentration was about 0.15 mol/L. The SEM results showed that without FeS (indissolvable) and FeSO4, steel suffered slight corrosion, meanwhile several pittings appeared after 42 h. Compared with that of FeS, much more pittings grew on the specimens with FeSO4. The corrosion product was mainly mackinawite.

Kinetic study on the corrosion behavior of AM60 magnesium alloy with different Nd contents

AM60 alloys with different Nd contents were melted, refined and prepared in vacuum resistance furnace. The alloys were investigated by weight loss test in 3.5% NaCl solution at 25°C. The obvious changes of microstructures before and after the corrosion were characterized by scanning electron microscopy and X-ray diffraction. With the use of experimental data, a combination model was established to describe the galvanic corrosion rate of AM60 alloys. The constant of apparent corrosion rate (k) was calculated. The effect of Nd content on the grain size (d), organizational structure and corrosion rate of specimens were discussed. The results showed that the constant of apparent corrosion rate was affected by Nd content. Their relationship is described as k=0.6exp(-2.7Nd%)+0.58. The maximum and minimum value of k is 1.21 and 0.53μm/h, respectively. The reason for k decreasing is that trace Nd refined the grain size and generated different forms of Al11Nd3 phases. Corrosion protection film was formed in the area near rare earth-enriched phase. The film played an important role in corrosion together with the corrosion products on the surface of the alloy, indicating an improvement of corrosion resistance of AM60 alloys.

Hot Corrosion Behavior of Bare, Cr3C2-(NiCr) and Cr3C2-(NiCr) + 0.2wt.%Zr Coated SuperNi 718 at 900 °C

Corrosion in incinerators, power plants, and chemical industries are frequently encountered due to the presence of salts containing sodium, sulphur, and chlorine. To obviate this problem, bare and coated alloys were tested under environments simulating the conditions present inside incinerators and power plants. 0.2 wt.% zirconium powder was incorporated in the Cr3C2-(NiCr) coating powder. The original powder and Zr containing powder was sprayed on Superni 718 alloy by D-gun technique. The bare and coated alloys were tested under Na2SO4 + K2SO4 + NaCl + KCl and Na2SO4 + NaCl environment. The corrosion rate of specimens was monitored using weight change measurements. Characterization of the corrosion products has been done using FE-SEM/EDS and XRD techniques. Bare and coated alloys showed very good corrosion resistance under given molten salt environments. Addition of 0.2wt.%Zr in Cr3C2-25%(NiCr) coating further greatly reduced the oxidation rate as well as improved the adherence of oxide scale to the coating surface during the time of corrosion.

Atmospheric corrosion of Mg–rare earth alloy in typical inland and marine environments

The atmospheric corrosion behaviour of peak aged Mg–5Y–7Gd–1Nd–0·5Zr alloys in typical land (Beijing) and marine (Qingdao) environments were investigated by optical microscopy, SEM and X-ray diffraction. The weight loss rates and residual mechanical properties were analysed. The atmospheric corrosion rates of specimens in a typical marine environment were higher than those in land environment. The results demonstrated that temperature, relative humidity and inorganic salts at field exposed sites played an important role in atmospheric corrosion behaviours. The results of our investigation may find wider applications for Mg–rare earth alloys in atmospheric environments.

Corrosion Behaviors of Mg-7Gd-5Y-1Nd-0.5Zr Alloys in CO<sub>2</sub> Atmosphere under Different Relative Humidity

The corrosion behaviors of peak-aged Mg-7Gd-5Y-1Nd-0.5Zr alloys in CO2atmosphere under different relative humidity were investigated by OM, SEM. The weight loss rates, corrosion morphology and residual mechanical properties were also analyzed. The corrosion rates of specimens in CO2atmosphere at 70% relative humidity were highest than others. Relevancy of the influence factors included relative humidity and concentration of CO2were researched. The results show that relative humidity and concentration of CO2in the environment both played an important role in corrosion behaviors.

The efficiency of surface-applied corrosion inhibitors as a method for the repassivation of corroded reinforcement bars embedded in ladle furnace slag mortars

Surface-applied corrosion inhibitors are investigated as an efficient method for the repassivation of corroded rebars embedded in mortar specimens, with ladle furnace slag. Prismatic specimens measuring 6×8×2cm3, into which 3 steel rebars had been embedded, were analyzed through electrochemical and gravimetric tests. The results show that the corrosion inhibitors are more effective on the reference specimens than on the specimens with LFS and are capable of lowering corrosion rate in specimens with chloride ion percentages of 0.8%, but are not effective on any of the specimens with chloride ion percentages of 1.2% and 2.0% by weight of cement.

Corrosion of Permeable Concrete under Simulated Acid Rain

A long time immersion test of concrete specimens in dilute sulfuric acid is carried out to study the permeable concrete material aging rule under the action of the sulfuric acid. The experiment is designed by uniform design containing 4 factors and 10 levels and the soaking solution pH value is 4.00. To measure acid consumption, titration sulfuric acid with concentration of 0.125mol / L is used to keep original pH value of soaking solution, through which the corrosion rate of specimens can be determined. After certain immersion time, the specimens are dried and weighted and the weight changes of the specimens are recorded. The results show that corrosion rate of permeable concrete shares the same family of corrosion rate functions with those of ordinary concrete and mortar. However, the weight of specimen fluctuates with the soaking time, so that it may not be a proper index of corrosion.

The influence of solution treatment temperature on microstructure and corrosion behavior of high temperature ageing in 25% Cr duplex stainless steel

In 25% Cr duplex stainless steels, the effect of prior-solution treatment temperature (STT) on the microstructure and corrosion behavior with ageing at 750 °C and 850 °C was investigated. The results revealed that the precipitation rate of σ-phase was fast in the early stage of ageing for 80 min, and then got slower with ageing time up to 330 min. The σ-phase formation was effectively suppressed by raising STT from 1060 °C to 1230 °C especially for ageing at 750 °C. Consequently, the corrosion rate of specimen was dependent on the amount of σ-phase precipitation, and was lowered due to higher STT, and more σ-phase precipitation can lead to the transition from metastable to stable pitting with ageing at 750 °C up to 330 min. Pitting occurred easily around coarse σ precipitates and caused selective dissolution in ferrite. The longer ageing time increased intergranular corrosion (IGC) susceptibility, whereas higher STT contributed to better resistance to IGC.