Pit Depth Research Articles

Determination of Physical Properties of FYM for the Development of FYM Shredder cum Spreader

A research work was undertaken at the Department Agricultural Engineering, Regional Agricultural Research Station, Tirupathi, Andhra Pradesh, India during 2020 to study the physical properties of FYM for the designing the tractor mounted FYM spreader. Application of FYM increases the soil fertility. FYM contained almost all essential nutrients required for soil. The important FYM physical properties like moisture content, bulk density, angle of repose, coefficient of friction are required for development of FYM shredder cum spreader. The FYM is heterogeneous mixture and its moisture content varies at different depths stored in manure pits for measuring the physical characteristics, three depths of manure pits viz., 0-20, 20-40, 40-60 cm collected and were used. Designing The physical properties found in FYM like moisture content, bulk density, angle of repose and coefficient of friction and sieve analysis of FYM at different depth of manure pit were 61% db 20% wb,0.650 gcm-3,71.03 and 34° respectively. The initial bulk density form before the operation 0.650 g cm-3andclod size is major at 70% at 50 mm screen opening after shredder operation the bulk density decreases 0.250 g cm-3 and 40% of FYM retained less than 10 mm sieves at the shredder speed is 255 RPM. The developed shredder was successful in reducing 70% aggregation size from more than 50 mm-less than10 mm sieve opening which is desirable form of FYM application.

Influence of Electron Mediator on Microbiologically Influenced Corrosion Behavior of 2024 Aluminum Alloy

In microbiologically influenced corrosion (MIC) caused by sulfate-reducing bacteria (SRB), extracellular electron transfer (EET) between metals and microorganisms affects the metal corrosion process. In this work, the effect of the electron mediator riboflavin on the EET-MIC behavior of 2024 aluminum alloy (AA2024) was investigated by electrochemical methods, surface analysis techniques, focused ion beam, scanning electron microscopy, and x-ray photoelectron spectroscopy techniques. The results showed that the electron mediator was significantly able to accelerate SRB attack against AA2024. SRB utilized to consume H+ to accelerate its own metabolism and promoted the corrosion of AA2024, resulting in the formation of corrosion product AlOOH and Al(OH)3. The addition of electron mediator riboflavin increased the electron transfer efficiency and affected the reaction rate constant to accelerate the corrosion rate of aluminum alloy. The addition of 10 ppm riboflavin led to denser corrosion product biofilms on the surface of the aluminum alloy, which accelerated the formation of NaAlO2. Cl− diffused into the film layer through the pores of the surface of the aluminum alloy and was adsorbed into the film layer to induce pitting corrosion on the surface of the aluminum alloy. A large amount of SRB was attached, which resulted in an increasing pit depth on the surface of the aluminum alloy. Riboflavin accelerated the electron transfer process from the surface of the aluminum alloy across the cell wall to the cytoplasm, which led to serious corrosion of the aluminum alloy. The distribution of SRB in biofilm and the longitudinal distribution of bacteria in the process of pitting corrosion showed that the addition of electron mediators increased the depth of pits in aluminum alloys. Bacteria in the pitting area gathered at the bottom of the biofilm, and the pits were rich in Ca, P, and other elements.

Влияние жесткости угловых зон котлованов на перемещения подпорных стен в песчаных грунтах

Engineering calculations in the spatial formulation, as well as the results of field observations, show a significant decrease in lateral displacements of the foundation pit retaining walls in the area of the corner zones. At the same time, in design practice, a large number of decisions are made on the basis of calculations in a flat formulation. For pits with a depth of more than 10 m, the influence of corner zones can make a significant contribution to the reduction of movements and, as a result, internal forces in the retaining walls and restraint systems. The underestimation of the corner effect leads to an increase of the retaining structures construction cost.
 This article presents the results of FEM calculations studies of the monolithic reinforced concrete wall functioning in the corner zones of pit in sandy soils. As a result, it was revealed that the movement of the diaphragm wall in the area of the corner zones of the foundation pit is influenced by such factors as: the pit depth, the angle between retaining walls, and the stiffness of the retaining wall and struts. At the same time, the properties of the sand and the stiffness of the retaining wall and struts do not affect the distribution of displacements in the corner zones.

Wettability surface and friction characterisation of ZrO2 ceramics by femtosecond laser texturing

PurposeThe purpose of this study is to process the wettability surface of the ZrO2 ceramics to improve their surface friction performance.Design/methodology/approachMicrotexture was processed on the surface of ZrO2 ceramics using a femtosecond laser. The three-dimensional texture morphology, surface contact angle, friction curve and wear morphology were measured by the laser confocal microscope, the contact angle meter, the reciprocating friction and wear tester and the scanning electron microscope, respectively. Based on Wenzel and partial impalement models, a geometric model of micro pits is established to study the influence mechanism of micro pit depth, diameter and distribution density on wettability and to analyze the relationship between surface wettability and tribological properties.FindingsThe results show that changing the geometric characteristics of the texture will lead to a change in the solid-liquid contact mode, and then lead to a change of in the surface contact angle. Wettability is an essential factor that affects the reduction of surface friction. The construction of a reasonable texture can enhance the surface hydrophilicity, which is conducive to the formation of a lubricating film on the ceramic surface, thereby reducing abrasive and adhesive wear, and improving the wear resistance of the ZrO2 ceramic surface.Originality/valueThe results provide a theoretical reference for femtosecond laser surface texture wettability regulation and tribological performance improvement.

Development of Pitting Corrosion for Mild Steel Exposed to Particulate Media and Natural and Nutrient-Dosed Seawaters

Corrosion of mild steel in contact with both seawater and particulate media has important practical implications. It is considered herein for coupon exposures up to 2 y in 0.05 mm and 0.425 mm (nom.) granular media in natural Pacific Ocean seawater and in seawater dosed with calcium nitrate ostensibly to stimulate microbiological corrosion. The observed pit depths were consistent with an empirical bi-modal corrosion prediction model and overall lowest for smaller particle sizes and greatest without particles. Contrary to expectations, nutrient dosing tended to reduce pit depths. The observations are discussed in light of earlier observations and for relevance to practical implications.

Corrosion of the interior steel surfaces of offshore monopiles

ABSTRACT The present paper reports on four-year field investigations aimed at ascertaining internal corrosion rates for offshore wind-power generation monopiles, despite these being designed to obviate internal corrosion through oxygen exclusion. Results for mild steel strips within the enclosed, quiescent, uPVC simulated seawater environments are presented as a function of relative to mean tide level, period of exposure and localised pollution of seawater. Detailed pit depth measurements are also reported for various exposure periods, with the magnitude of such corrosion displaying a bi-modal behaviour as a function of exposure time, consistent with much other data. No evidence was found of the classical corrosion profile for vertical steel structures (e.g. piles) or of accelerated low water corrosion usually associated with microbiologically influenced corrosion caused by elevated seawater nutrient concentrations. It is proposed that the observed corrosion behaviours primarily are the result of the shielded quiescent environment. The practical implications are briefly discussed.

Understanding Initiation and Evolution of Pitting Corrosion in 7075-T6 Aluminum Alloy by Four-Dimensional X-Ray Microtomography

X-ray microcomputed tomography was conducted on an AA7075-T651 sample immersed in a 3.5 wt% NaCl solution to provide time-resolved measurements of localized corrosion. A nondestructive, volumetric analysis of pitting sites and local microstructural features followed, and quantitative results were combined with 2D and 3D visualizations. During alternating immersion periods, pitting was initiated at cathodic intermetallic inclusions and continued throughout the study. Rates of pit growth varied as a response to the decoupling of inclusions from the matrix, resulting in a start-and-stop trend that was observed in a significant number of examined sites. When a sample with a higher extent of cold rolling was examined with the same procedure, a finer and more homogeneous distribution of inclusions correlated with an increase in the maximum and mean pit depth. This change was attributed to the more frequent exposure of subsurface inclusions by localized corrosion, a phenomenon that mitigated the passivating effect of decoupling. Additionally, the effects of continuous immersion vs. alternate immersion were examined for metallurgically identical samples. Intermittent drying during the alternate immersion period destabilized the passive layer, increasing mean pit depth, while continuous immersion for 20 d produced a uniform and protective layer of corrosion product.

Mechanical property degradation of X80 pipeline steel due to microbiologically influenced corrosion caused by Desulfovibrio vulgaris.

Apart from pinhole leaks, MIC (microbiologically influenced corrosion) can also cause catastrophic failures such as pipe ruptures and support beam collapses due to mechanical property degradation or stress corrosion cracking. In this work, X80 pipeline steel dogbone coupons and square coupons were immersed in 150ml broths containing Desulfovibrio vulgaris, a common corrosive sulfate reducing bacterium (SRB), for up to 14days. The headspace volumes in the anaerobic bottles were increased from 150ml to 200ml and 300ml to increase MIC severity. After 14days of SRB incubation in ATCC 1249 culture medium with X80 coupons at 37°C, the sessile cell counts were 6.5 × 107 cells cm-2 for 150ml, 2.3 × 108 cells cm-2 for 200ml and 1.4 × 109 cells cm-2 for 300ml headspace volumes, respectively owing to reduced H2S cytotoxicity in the broth with a larger headspace because it allowed more biogenic H2S to escape from the broth. Weight losses were 1.7mg cm-2, 1.9mg cm-2 and 2.3mg cm-2 for 150ml, 200ml and 300ml headspace volumes, respectively. The corresponding pit depths were 2.6μm, 4.2μm and 6.2μm for 150ml, 200ml and 300ml headspace volumes, respectively. Electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic polarization results corroborated the increasing weight loss and pitting data trends as a result of increased headspace. Tensile testing of dogbone coupons after the 14-day SRB immersion test indicated that more severe MIC pitting led to a higher ultimate strain loss by up to 23% (300ml headspace) compared to the abiotic control, while the ultimate strength losses for all headspace volumes were quite small (3% and lower).

Three-Dimensional Morphology and Watershed-Algorithm-Based Method for Pitting Corrosion Evaluation

Pitting corrosion and stress concentration at rust pits are the principal reasons for severe degradation in fatigue performance of corroded steel structures. The accurate evaluation of rust pits on rough and uneven corrosion surfaces is the foundation of fatigue life estimation for corroded steel structures. In this paper, a new method for the identification, extraction, and evaluation of rust pits on the surface of corroded steel structures was proposed based on a three-dimensional morphology and watershed algorithm. An accelerated corrosion experiment was first executed to acquire corroded steel plates, and then surface profile measurements were conducted to obtain the three-dimensional morphology of the corroded steel surfaces. Furthermore, the surface topography data of the corroded steel surfaces were written into a gray matrix through coordinate transformation. Then, the gray matrix was successively filtered and gradient-mapped, and the watershed was calculated to obtain the pit mark matrix and pit depth matrix. A calculation method for the size and shape of rust pits was consequently developed, and a statistical analysis of the extraction results of the rust pits was also conducted. The results showed that rust pit density had a peak value at the corrosion duration of 3 months, and rust pit density showed a fluctuating process with corrosion duration that continued to increase until 15 months. The values of the depth diameter ratios of rust pits were concentrated in the range of 0.1~0.8. With corrosion duration increasing from 3 months to 4, 6, 8, 12, and 15 months, the distribution range of the depth diameter ratios of rust pits decreased at first and then increased, followed by decrease and, finally, increase. The width distribution of the rust pits was independent of the depth distribution of the rust pits. The values of the volume ratios were mostly distributed between π/12 and π/4, and the shapes of most rust pits were similar to half (ellipsoidal) spheres.

Substantiation of the optimal parameters of the bench elements and slopes of iron ore pits

Purpose. To establish the optimal parameters of the bench elements and slopes of the pit at the mining of Horishne-Plavnynske and Lavrykovske deposits of ferruginous quartzites for further use of these parameters at the design. Methodology. Methods for determining the influence of the bench height on the productive pit capacity involves taking into account the quality of the ore, the rate of the mining front advancement, the rate of pit depth at the mining operations, the total length of the mining front, as well as the angles of the working and non-working pit slops. Findings. The most effective parameters for mining benches and slopes of an iron ore pit are considered, using the example of the Ferrexpo Poltava Mining. Parameters of the bench elements with a height of 2430 m have been established, which are worked out in layers with a height of 12, 10 and 15 m. The studies carried out made it possible to establish that layers with a height of 10 m, followed by the final and temporary pit contour with a bench height of 30 m, can improve safety due to the flattened slope of the pit up to 45, while, with a bench height of 15 m, the angle of inclination of the slope will be 47. Originality. The established dependence of the pit ore productivity in percentage on the bench height suggests that with an increase in the bench (layer) height, the ore productivity of the pit decreases. Determination of the influence of the working bench (layer) height on the total volume of ore losses in the design contour of the pit makes it possible to assert that at constant angles of the bench slope and the ore deposit fall, the values of operating losses and clogging change in direct proportion to the height. Practical value. A technological scheme has been developed for the development of a bench with a height of 30m with a layer thickness of 10 m, which makes it possible to improve safety in the pit by pit slope flattening to 45, to reduce the cost of ore mining by optimizing drilling operations (shorter drilling time per well, reduction of overdrilling and etc.) and thereby improve the economic performance of the enterprise.

Effectiveness of multi-physics numerical model in simulating accelerated corrosion with spatial and temporal non-uniformity

This study is motivated by the need to develop an efficient numerical model to simulate non-uniform interfacial degradation of reinforcing steel in concrete in an accelerated corrosion setup considering the influence of differential aeration, moisture and conductivity. In this study, a multi-physics finite element (FE) model is presented to simulate spatially and temporally non-uniform surface topography of corroding steel with rust layer, and eliminates the assumption of uniform mass loss and its linear variation with time as per available literature that uses classical approach of Faraday’s law. The model is validated experimentally with accelerated corrosion setup. Unlike previous studies, pore saturation (PS) is continuously monitored and its existing experimental correlations with conductivity and oxygen diffusivity are adopted so that the model can be extended to simulate natural corrosion to enhance the accuracy of service life predictions. These evaluations can be made completely nondestructive and in real-time eliminating the challenges in capturing the influence of environment by the use of alternative parameters such as relative humidity from real climate change predictions. The key findings from the investigation reveal that incorporating local environmental parameters measured in situ allows for the model to naturally evolve with anodic and cathodic locations on steel surface avoiding the need to assume predefined locations. It is envisioned that the developed multi-physics FE model can be used as a reliable substitute to accelerated corrosion experiment which is frequently used for durability studies of corroding reinforced concrete (RC) members. It is shown that the daily and cumulative mass loss evaluated from the degraded surface topography of the corroded rebar using the simulated model are in good agreement with those evaluated experimentally. Further, the maximum pit depth evaluated from the simulated surface is validated that has valuable applications in estimating degraded strength of corroding steel and service life of RC members.

Data augmentation using conditional generative adversarial network (cGAN): Application for prediction of corrosion pit depth and testing using neural network

Machine learning (ML) based algorithms, due to their ability to model nonlinear and complex relationship, have been used in predicting corrosion pit depth in oil and gas pipelines. Class imbalance and data scarcity are the challenging problems while training ML models. This paper utilized a conditional generative adversarial network (cGAN) to handle class imbalance problem in a corrosion dataset by generating new samples. Utility of the cGAN data augmentation is evaluated by training an artificial neural network (ANN) model. In addition, random oversampling and Borderline-SMOTE data generating techniques are used for comparison with cGAN. The testing accuracy of the ANN model increased greatly when trained by the cGAN based augmented dataset and this model performance improvement can be useful for a pipeline integrity management.

Assessing the efficacy of non-destructive testing methods to detect pitting corrosion

ABSTRACT Calibration of the non-destructive testing (NDT) methods for pipeline inspections is commonly done via machined defects with simple shapes and known sizes. However, such defects do not represent, e.g. an actual pit morphology observed in the field, which could lead to the unreliable interpretation of the inspection results. This work proposed a systematic approach to create and characterise real pits in stainless steel pipe specimens to assess the sensitivity of selected NDT methods. Pipe samples with three different diameters and thicknesses were used. Pits of different geometries and dimensions were generated by electrochemical methods, and immersion in an acidic ferric chloride solution filled in pre-drilled holes on the external surface of the specimens. NDT methods including radiography, Eddy current and dye penetrant testing were used for detecting and sizing the pits. The results were then compared with true pit depths obtained from cross-section analysis. Radiography and Eddy current methods failed to detect small pits with depths less than 70 µm. The porous metal cover on the pit mouth affected the detectability of radiography, while it had little impact on Eddy current testing. The findings of this investigation could be used to design training and calibration blocks for NDT methods.

Effect of substrate orientation and anisotropic strength on corrosion pits

The complexities of pitting corrosion and its associated pit morphologies are critical for predicting and preventing pit-related failure in materials. With the advances in computational tools, modeling of pitting corrosion has lately gained momentum. We recently developed a phase field model for 3-D pit morphology, and in the current work, the model is utilized to gain insight into the role of substrate orientation and anisotropic strength on crystallographic pits. The influence of these parameters on pit morphology and corrosion metrics such as pit volume, current, pit area, current density, and pit depth are studied. The crystallographic pit morphology changes with substrate orientation but not significantly with anisotropic strength. The anisotropic strength strongly influences the corrosion metrics whereas most corrosion metrics remain unaffected by substrate orientation.

Microbiologically influenced corrosion of titanium by Desulfovibrio vulgaris biofilm under organic carbon starvation

Desulfovibrio vulgaris biofilm was pre-grown on Ti coupons for 7 d and then the biofilm covered coupons were incubated again with fresh culture media with 10 % (reduced) and 100 % (normal) carbon source levels, respectively. After the pre-growth, sessile D. vulgaris cell count reached 107 cells/cm2. The sessile cell counts were 2 × 107 and 4.2 × 107 cells/cm2 for 10 % and 100 % carbon sources, respectively after the subsequent 7 d starvation test. The maximum pit depth after the 7 d pre-growth was 4.7 µm. After the additional 7 d of the starvation test, the maximum pit depth increased to 5.1 µm for 100 % carbon source vs 6.2 µm for 10 % carbon source. Corrosion current density (icorr) from potentiodynamic polarization data at the end of the 7 d starvation test for 10 % carbon source was more than 3 times of that for 100 % carbon source, despite a reduced sessile cell count with 10 % carbon source. The polarization resistance (Rp) started to decrease within minutes after 20 ppm (w/w) riboflavin (electron mediator) injection. The carbon starvation data and riboflavin corrosion acceleration data both suggested that D. vulgaris utilized elemental Ti as an electron source to replace carbon source as the electron donor during carbon source starvation.

Effects of Strength-Modified Grinding on the Surface Microstructure and Mechanical Properties of 30CrMnSiA Bearing Steel

The novel strengthen-modified grinding technique (SMGT) treatment was carried out on 30CrMnSiA bearing steels to investigate the effect of jet pressure (0.2–0.6 MPa) and jet angle (30–90°) on its surface micromorphology, microstructure, and mechanical properties. The results show that, under the compound effects of the impact of steel beads and the abrasive powder micro-cutting, the surface of 30CrMnSiA specimens treated by the SMGT has a microstructure with plenty of micropits inside the pits and overlaps between pits. The pit width, depth, and bulge height positively correlate with jet pressure. The pit depth and bulge height positively correlate with jet angle, while the pit width negatively correlates with jet angle. When a pit morphology is produced, plenty of plastic deformation leads to grain refinement, and the lattice distortion induces retained austenite transformation to martensite. Grain refinement and increased martensite content are the main reasons for the significant increase in hardness on the SMGT-treated specimen surface. With the optimized processing parameters, the grain size of the surface was reduced to 10.14 µm, and the martensite content and hardness of the surface layer rose to 51.35% and 377.6 HV0.2.

Microbiologically influenced corrosion of FeCoNiCrMn high-entropy alloys by Pseudomonas aeruginosa biofilm.

Pseudomonas aeruginosa is widely found in industrial water and seawater. Microbiologically influenced corrosion (MIC) caused by P. aeruginosa is a serious threat and damage to the safe service of steel materials. In this study, the MIC behavior of FeCoNiCrMn high-entropy alloy (HEA) by P. aeruginosa biofilm was investigated in the simulated marine medium. The maximum pitting depth of the HEA coupons in the P. aeruginosa-inoculated medium was ~4.77 μm, which was 1.5 times that in the sterile medium. EIS and potentiodynamic polarization results indicated that P. aeruginosa biofilm reduced the corrosion resistance of the passive film of HEA coupons and promoted its anodic dissolution process. XPS and AES results further demonstrated that P. aeruginosa interfered with the distribution of elements in the passive film and significantly promoted the dissolution of Fe.

Pitting Propagation Behavior on Low Alloy AISI 4130 (UNS G41300) Steel Exposed to Various Alkaline Earth Metal Chlorides Using the 1-D Pit Method

This study examined pit propagation to elucidate whether alkali and alkaline earth metal chloride saltssuch as RbCl affect pitting behavior in distinctly different manner than NaCl. Pit propagation studies were conducted on a low alloy steel using one-dimensional (1-D) pit method over pit depths from 300-1000 µm. LSV and EIS of planar electrodes of 4130 in a range of Cl- solutions were conducted and revealed no differences in impedance, open circuit, corrosion potential (Ecorr), passive current density (ipass), and pitting potential (Epit) as a function of salt type. In the case of one-dimensional pits during fast downward scan rates, the saturation potential (Esat) varied as a function of salt type and pit depth when pits were shallow. Mass transported limited current density also differed with salt type in shallow pits when other alkali metal and alkaline metal cations where present. The pit surface potential (Esurf) of activated pit surfaces reached Ecorrprior to establishing a condition where the pit electrolyte surface concentration (Csurf) was less than the critical concentration for active acidified pitting (Csurf<Ccrit) in this marginally passivating steel. For various Esurf and pit current density (ipit) combinations at constant Csurf where Ccrit< Csurf < Csat, E-log(i) plots were constructed using the method of Li, Tianshu to create IR ohmic voltage corrected Tafel plots at fixed pit solution concentrations. Under these conditions, the influence of salt identity on charge transfer controlled kinetics was reexamined and slight differences in Tafel behavior were found. Differences in metal cations exert no effect on passive planar electrodes and only effect pit propagation stage in shallow pits.

Repassivation Temperature of One-Dimensional Artificial Pits in Stainless Steel

A new framework has been developed in recent works to describe pit growth stability 1-8, based on which many critical scientific issues in localized corrosion were addressed, such as the rate-controlling step in pit growth, the salt film growth and self-regulating mechanism, and the kinetics and the activation energy of metal dissolution in the local pit environment. Although many new insights were generated, there are still some phenomena that are not well understood, such as the pit repassivation temperature (T rp). According to the new framework, T rp is predicted to decrease with the increase of applied potential (E app). However, T rp sometimes exhibits an unexpected dependence on E app that contradicts with the prediction, and the underlying mechanism is not clear.In this study, T rp of one-dimensional artificial pits made from 316L stainless steel was investigated in 3.5 wt.% NaCl by downward temperature scanning. For a given pit depth, T rp exhibits an unexpected “S” dependence on applied potential, which has never been reported previously. Further analysis shows that this relationship is derived from repassivation underneath the salt film, which is different from repassivation that occurs when the pit surface concentration decreases below a critical value. This indicates that there is a reversal of the effect of the salt film on pit growth stability. The systematic study shows that such a reversal depends on temperature, E app, and pit depth. Acknowledgments: This work was supported as part of the Center for Performance and Design of Nuclear Waste Forms and Containers, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0016584.References G. S. Frankel, T. Li, and J. R. Scully, Journal of the Electrochemical Society, 164 (4), C180-C181 (2017).T. Li, J. R. Scully, and G. S. Frankel, Journal of The Electrochemical Society, 165 (9), C484-C491 (2018).T. Li, J. R. Scully, and G. S. Frankel, Journal of The Electrochemical Society, 165 (11), C762-C770 (2018).T. Li, J. R. Scully, and G. S. Frankel, Journal of The Electrochemical Society, 166 (6), C115-C124 (2019).T. Li, J. R. Scully, and G. S. Frankel, Journal of The Electrochemical Society, 166 (11), C3341-C3354 (2019).T. Li, J. Wu, and G. S. Frankel, Corrosion Science, 182 109277 (2021).T. Li, J. Wu, X. Guo, A. M. Panindre, and G. S. Frankel, Corrosion Science, 193 109901 (2021).T. Li, D. E. Perea, D. K. Schreiber, M. G. Wirth, G. J. Orren, and G. S. Frankel, Corrosion Science, 174 108812 (2020).

(Digital Presentation) Progress Towards the Key Factors Governing Pit Stability

The pit stability product—defined as the product of pit depth and dissolution current density (x·i)—was first introduced by Galvele as the criterion indicating the conditions that sustain a critically acidic solution within the pit. The one-dimensional (1D) electrode is the most commonly used experimental configuration for determining the pit solution chemistry and pit stability product. In our current works, a ‘sandwich’ like 1D pit electrode was developed, which enabled the in-situ and ex-situ visualization of pit depth. A methodology that avoids lacy cover formation was proposed to pre-dissolve a Type 316L stainless steel (SS) 1D electrode to specific depths. Based on the new methodology and mathematical models, it was found that 1D Fick’s law of diffusion could not be used to estimate the pit stability product under a salt film because electro-migration had a measurable contribution (i.e., 67%) to the dissolution current. Although the diffusion coefficient of metal cations decreased with an increasing concentration inside the pit, it could be replaced by a constant diffusion coefficient to estimate the pit stability product, defined as an equivalent diffusion coefficient in our work. Later, a more comprehensive mathematical model, which included hydrolysis reactions and activity, was built to predict the local chemistry within the pit cavity. Recently, a galvanostatic method was developed to estimate the critical pit stability product of Type 316L SS, which was between 0.8 and 0.9 A/m in 0.6 M NaCl at 25°C, findings that were also confirmed by mass transport modelling. Here, we will present the proposed improved theoretical framework and discuss the next steps in modelling the propagation of pits in stainless steels.