The Effect of Hydrogen Evolution on Acidification in Alloy 600 and 304 Stainless Steel Crevices at 288 C

CORROSION ◽  
1980 ◽  
Vol 36 (10) ◽  
pp. 544-549 ◽  
Author(s):  
D. F. TAYLOR ◽  
M. SILVERMAN
Keyword(s):  
Stainless Steel ◽  
Direct Reduction ◽  
304 Stainless Steel ◽  
304L Stainless Steel ◽  
Alloy 600 ◽  
Hydrogen Ions ◽  
Standard Potential ◽  
Upper Limit ◽  
Hydrogen Fugacity ◽  
Thermodynamic Instability

Abstract Crevice experiments with 1 mm ID Alloy 600, 304L stainless steel, and platinum tubing have shown that to a large extent, equilibrium thermodynamics controls the mode and degree of crevice corrosion in aqueous systems at 288 C. When crevices enter a potential/pH region of thermodynamic instability for the crevice solution, direct reduction of water or hydrogen ions by the metal competes with macrocell acidification and the hydrogen fugacity strongly influences the degree of acidity which can be attained or maintained. The platinum system undergoes no such thermodynamic transition and acidification ceases only as the corrosion macrocell approaches equilibrium. Platinum crevice behavior indicates an upper limit of 0.60 V (SHE) for the Pt(II) oxide/Pt standard potential at 288 C.

Some Effects of Electrolyte Composition and Heat Treatment on the Aqueous Crevice Corrosion of Alloy 600 and Type 304 Stainless Steel at 288 C

CORROSION ◽  
1980 ◽  
Vol 36 (9) ◽  
pp. 447-458 ◽  
Author(s):  
DALE F. TAYLOR ◽  
MICHAEL SILVERMAN
Keyword(s):  
Stainless Steel ◽  
Metal Ion ◽  
Direct Reduction ◽  
304 Stainless Steel ◽  
Alloy 600 ◽  
Dissolution Model ◽  
Ion Effects ◽  
Type 304 ◽  
Type 304 Stainless Steel ◽  
The Relationship

Abstract Crevice experiments with small bore Alloy 600 and Type 304 stainless steel tubing demonstrated that specific ion effects and heat treatments which change the microstructure of exposed surfaces, can counteract the charge transport/metal hydrolysis mechanism of crevice acidification. The results suggested that competition between the macroscopic electrochemical cell or “macrocell” mechanism, and direct reduction of water, hydrogen ions, or anions by the alloy, established the direction and extent of changes in pH. A simple uniform dissolution model correctly predicted the relationship among metal ion concentrations and the pH in a crevice when only macrocell corrosion occurred.

scholarly journals Investigation of Microstructure and Corrosion Resistance of Dissimilar Welded Joint between 304 Stainless Steel and Pure Copper

2019 ◽  
Vol 1 (3) ◽  
pp. 76-82
Author(s):  
Sorush Niknamian
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Arc Welding ◽  
Pure Copper ◽  
Welding Process ◽  
Steel Part ◽  
304 Stainless Steel ◽  
Dissimilar Metals ◽  
304L Stainless Steel ◽  
Shielded Metal Arc Welding

Nowadays, welding of dissimilar metals has become significant. In this process, a number of parameters including but not limited to type of electrode, amount of current, preheating temperature, and welding rate, that are essential to be taken into account. For welding of dissimilar metals, various methods are exploited including shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). The stimulus for studying welding of 304L stainless steel to pure copper originates from difficulties in joining copper parts of           water-circulating molds to their steel part. In this study, the welding is performed on plates of steel and copper using SMAW, GTAW and combined SMAW+GTAW welding methods with    EL-CuMn2, ENiCrMo-6 and ER70S-4 electrodes. In order to investigate the microstructure and corrosion resistance behavior of welds, the samples were characterized using microstructural study and polarization test. It was observed that among all four welding methods, only combined SMAW+GTAW welding process resulted in successful joint between 304L stainless steel and copper. Both obtained joints possess suitable microstructure and corrosion resistance.

Atmospheric pitting corrosion of 304L stainless steel: the role of highly concentrated chloride solutions

2015 ◽  
Vol 180 ◽  
pp. 251-265 ◽  
Author(s):  
Steven R. Street ◽  
Na Mi ◽  
Angus J. M. C. Cook ◽  
Haval B. Mohammed-Ali ◽  
Liya Guo ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Large Data ◽  
304 Stainless Steel ◽  
Data Sets ◽  
304L Stainless Steel ◽  
Active Dissolution ◽  
Pitting Potential ◽  
Enhanced Dissolution ◽  
Heterogeneous Alloy

The morphology of atmospheric pitting corrosion in 304L stainless steel plate was analysed using MgCl2 droplets in relation to changes in relative humidity (RH) and chloride deposition density (CDD). It was found that highly reproducible morphologies occur that are distinct at different RH. Pitting at higher concentrations, i.e. lower RH, resulted in satellite pits forming around the perimeter of wide shallow dish regions. At higher RH, these satellite pits did not form and instead spiral attack into the shallow region was observed. Increasing CDD at saturation resulted in a very broad-mouthed pitting attack within the shallow dish region. Large data sets were used to find trends in pit size and morphology in what is essentially a heterogeneous alloy. Electrochemical experiments on 304 stainless steel wires in highly saturated solutions showed that the passive current density increased significantly above 3 M MgCl2 and the breakdown pitting potential dropped as the concentration increased. It is proposed that the shallow dish regions grow via enhanced dissolution of the passive film, whereas satellite pits and a spiral attack take place with active dissolution of bare metal surfaces.

Finite Element Modeling of Burr Formation Process in Drilling 304 Stainless Steel

1999 ◽  
Vol 122 (4) ◽  
pp. 612-619 ◽  
Author(s):  
Y. B. Guo ◽  
D. A. Dornfeld
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Formation Process ◽  
Fem Simulation ◽  
Ductile Failure ◽  
304 Stainless Steel ◽  
Burr Formation ◽  
304L Stainless Steel ◽  
Machined Surface ◽  
Mechanical Coupling

A 3D finite element model was developed for the simulation of drilling burr formation processes of 304L stainless steel. The nonlinear thermo-elastic-plastic model simultaneously accounts for dynamic effects of mass and inertia, strain hardening, strain rate, automatic mesh contact with friction capability, material ductile failure and temperature-mechanical coupling. Material ductile failure criteria were proposed to simulate drilling burr formation. Based on a series of stress contours and the progressive deformation of the workpiece edge obtained from simulation, a drilling burr formation mechanism was proposed and divided into four stages: initiation, development, pivoting point, and formation stages with cap formation. The burr thickness is largely determined by the distance between the pre-defined machined surface and the pivoting point, while the burr height is determined by the positions of the pivoting point and the cap formation. The FEM simulation demonstrates the dominant roles of negative shearing and bending mechanisms in the drilling burr formation process. The simulation results coincide with phenomenological observations of burr geometry from drilling 304 stainless steel and plasticine work materials. [S1087-1357(00)01202-8]

Caustic Stress Corrosion Cracking Studies at 288 C (550 F) Using the Straining Electrode Technique — Comparison of Alloy 600, Alloy 800, and Type 304 Stainless Steel

CORROSION ◽  
1978 ◽  
Vol 34 (6) ◽  
pp. 198-209 ◽  
Author(s):  
J. R. CELS
Keyword(s):  
Stainless Steel ◽  
Electrical Potential ◽  
Open Circuit ◽  
Grain Structure ◽  
304 Stainless Steel ◽  
Nickel Wire ◽  
Alloy 600 ◽  
Alloy 800 ◽  
Type 304 ◽  
Type 304 Stainless Steel

Abstract Constant pull rate tests were conducted on tensile specimens of Inconel Alloy 600, Incoloy Alloy 800, and Type 304 stainless steel in deaerated 10% NaOH solution at 288 C (550 F) with a cover gas of 5% H2 in N2. The pull rate used for most experiments was 3.3 x 10−6 cm/s, which corresponds to an initial strain rate of 3 x 10−6 s−1. The electrical potential of the specimens was controlled by a potentiostat using a nickel wire as a hydrogen reference electrode. Under open circuit conditions, Type 304 stainless steel specimens cracked rapidly, but Alloys 600 and 800 specimens exhibited only ductile fracture. However, cracks readily formed in Alloy 800 specimens at potentials in the +50 to +300 mV range and in Alloy 600 specimens at potentials in the +150 to +250 mV range. Scanning electron microscope (SEM) photographs of some of the cracked specimen surfaces showed the transition from ductile to brittle fracture as a consequence of changes in the specimen's electrical potential. Longitudinal metallographic cross sections also revealed the grain structure and the mode of cracking. They showed that the cracks were intergranular in Alloy 600 and Type 304 stainless steel specimens, and were transgranular in Alloy 800 specimens.

Characteristics of Duplex Treated AISI 304 Stainless Steel

2013 ◽  
Vol 592-593 ◽  
pp. 437-440
Author(s):  
Zdenek Joska ◽  
Jaromir Kadlec ◽  
Vojtěch Hruby ◽  
Zbynek Studeny ◽  
Tomas Binar
Keyword(s):  
Stainless Steel ◽  
Chemical Composition ◽  
Plasma Nitriding ◽  
Indentation Test ◽  
304 Stainless Steel ◽  
304L Stainless Steel ◽  
Duplex System ◽  
Aisi 304L ◽  
Aisi 304L Stainless Steel ◽  
Nitrided Surface

The duplex treatment consisted of a plasma nitriding at 470 °C for 4 h and subsequent coating with TiN layer was applied on AISI 304L stainless steel. The article is concerned to a study of the chemical composition and mechanical properties of duplex system. GDOES method, laser confocal microscopy, nanohardness and indentation test were employed to characterize the chemical composition, depth profiles, surface morphology, hardness, adhesion. The results show that the duplex surface system possesses a desirable combination of properties especially hardness. Adhesion of PVD coating was increased on nitrided surface.

Sensitization and Stress Corrosion Crack Response of Dual Certified Type 304/304L Stainless Steel

CORROSION ◽  
10.5006/2727 ◽  
2018 ◽  
Vol 74 (7) ◽  
pp. 737-746
Author(s):  
K.B. Fisher ◽  
B.D. Miller ◽  
E.C. Johns ◽  
R. Hermer ◽  
C. Brown ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
304 Stainless Steel ◽  
304L Stainless Steel ◽  
Low Carbon ◽  
Delta Ferrite ◽  
The Matrix ◽  
Oxygenated Water ◽  
Deformation Level ◽  
Type 304

Sensitization has previously been implicated in the stress corrosion cracking (SCC) susceptibility of carbon-containing Type 304 stainless steel (SS) in oxygenated water. Thus, Type 304L SS, with low carbon content, is expected to be resistant to sensitization and therefore SCC susceptibility. The current work evaluates the SCC response of two heats of dual certified Type 304/304L SS that exhibit different microchemical characteristics. One heat contains elevated boron content, while the other heat has delta ferrite stringers in the matrix. It is shown that both heats can be susceptible to SCC because of their unique microchemical features under certain combinations of heat treatment, water chemistry, and deformation level, while under other conditions they remain relatively resistant to SCC.

The corrosion resistance of low concentration ruthenium laser alloyed 304L stainless steel exposed to sulphuric acid at 25°C

2018 ◽  
Vol 65 (3) ◽  
pp. 263-270
Author(s):  
Josias Willem Van der Merwe ◽  
Ndivhuwo Brayner Nelwalani
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Sulphuric Acid ◽  
Laser Surface ◽  
304 Stainless Steel ◽  
304L Stainless Steel ◽  
Laser Alloying ◽  
Surface Alloying ◽  
Content Type ◽  
Laser Surface Alloying

Purpose This paper aims to study the effect of small ruthenium additions through laser surface alloying of 304L stainless steel on the corrosion resistance when exposed to a 1 M sulphuric acid solution at 25°C. Design/methodology/approach In this study, the characteristics of laser-alloyed surface layers enriched with low concentrations of ruthenium, less than 0.3 Wt.%, were evaluated. Samples were manufactured by performing laser surface alloying on a 304L stainless steel and using a 304 stainless steel powder enriched with ruthenium. The welded surfaces were cross-sectioned and the microstructure and chemical composition were analysed; in addition, the depth of penetration was determined. The corrosion characteristics of these surface welds were investigated through electrochemical analysis such as open circuit potential measurements and potentiodynamic scans. Findings It was found that with the addition of ruthenium levels of more than 0.2 Wt.%, the corrosion characteristics when exposed to 1 M sulphuric acid improved in the enriched welded zone. Research limitations/implications This study investigated the improvement of the surface layer of the 304L stainless steel because of the cost involved when ruthenium is alloyed in the bulk and showed that an improved corrosion resistance can be achieved in sulphuric acid at room temperature. Practical implications The hardness of the laser alloying was not significantly affected by the ruthenium, but more by the laser parameters. Originality/value This paper considers the improvement of 304L stainless steel through laser alloying with ruthenium.

scholarly journals Study on Oxidation of Stainless Steels During Hot Rolling

2012 ◽  
pp. 240-250
Author(s):  
Z. Y. Jiang ◽  
D. B. Wei ◽  
K. Tieu ◽  
J. X. Huang ◽  
A. W. Zhang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Oxide Scale ◽  
Stainless Steels ◽  
Hot Rolling ◽  
Steel Substrate ◽  
Substrate Surface ◽  
304 Stainless Steel ◽  
304L Stainless Steel ◽  
Scale Thickness

The oxidation of stainless steels 304 and 304L during hot rolling is studied in this paper. Results show the oxide scale thickness decreases significantly with an increase of reduction, and the oxide scales of both 304 and 304L stainless steels were found more deformable than the steel substrate. Surface roughness shows a complicated transfer during the hot rolling process due to the complexity of oxide scale characteristics. Also, surface roughness decreases with an increase of reduction. The friction coefficient increases with reduction in all cases, and the increase is more significant in the case of the 304 stainless steel than that of 304L stainless steel.

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