Occurrence Of Porosity Research Articles

Application of 3D Reservoir Geological Model on Es1 Formation, Block Nv32, Shenvsi Oilfield, China

Three-dimensional geological modeling of reservoirs is an essential tool to predict reservoir performance and improve the understanding of reservoir uniqueness in Es1 formation. The paper focuses on the use of petrel software to build three-dimensional reservoir geological model which characterizes and assesses block Nv32 that located in the west of the Shenvsi oilfield in the south of Cangzhou city, Hebei province of China, and has an oil-bearing area of 1.4 km2. This study is depending on integration data from well logs of 22 wells which provided from geology, geophysics, and petrophysics to identify and provide precise depict of the subsurface internal structure and the reservoir heterogeneity. Input data was used to build the structural model, sedimentary facies model, petrophysical properties (porosity, permeability, saturation, and N/G model, and finally to determine the reservoir volume. The lithological facies were simulated using the assigned value method. Moreover, Petrophysical properties (Porosity, permeability, oil saturation and net to gross) were constructed for each zone using the Sequential Gaussian Simulation method to guide the distribution of petrophysical properties of Es1 formation, block Nv32. Statistical analysis of the porosity, permeability, oil saturation and N/G model present that the porosity occurrence distribution is mainly concern between 0.2% - 36.39% of block Nv32 with an average porosity value of 17.5%, permeability between 0.017 mD to 974.8 mD, having an average permeability of 59.44 mD, oil saturation between 0.00 to 0.95 having an average value of 0.22, and N/G is mainly concentrated between 0.01 to 1.00 within an average value of 0.61. This research has indicated the reliability of the three-dimensional model technique as a suitable tool to provide a sufficient understanding of petrophysical distribution. The south-western and north-western indicate that oilfield is very promising an exploratory well should be drilled to find out the thickness and size of the reservoir.

Porosity and liquation cracking of dissimilar Nd:YAG laser welding of SUS304 stainless steel to T2 copper

In this study, we present experimental laser welding SUS304 stainless steel to T2 copper. The forming mechanism of fusion zone polygonal porosity and heat affected zone (HAZ) liquation cracking were systemically investigated and possible solutions to the welding process were also proposed. We deemed that the generation of HAZ liquation cracking mainly underwent three stages: crack incubation, crack initiation and crack growth. Formation of HAZ liquation cracking was closely related to precipitation of Cu-Fe compounds at grain boundaries and grain boundary liquation. The occurrence of porosity was determined by the keyhole instability correlated with fluid flow, keyhole free surface evolutions and composition segregation in a welding process. The susceptibility to HAZ liquation cracking can be effectively lowered by controlling the heat input during laser welding. In addition, the porosity in the fusion zone can be eliminated by reasonably adjusting laser deflection angle in the experiments, which greatly improved the microstructure and mechanical properties of welded joints.

Recrystallization and grain growth at the interface of a bimetallic colaminated strip composed of two different Fe-Ni alloys

Roll bonding is a solid-state welding process widely used to manufacture layered metal composites. Particular properties may thus be obtained using the physical features of each material of the composite. Bimetal plates consisting of two different Fe-Ni alloys were made by roll bonding followed by heat treatment for 90 minutes at various annealing temperatures. The effects of post-rolling heat treatments on the bonding strength of a bimetal strip were investigated in relation to the interface microstructure evolution. Both recrystallization and grain growth took place at the interface during annealing. In particular, nucleation of new grains as well as growing grains crossing the interface may have contributed to the improvement of the bonding strength. Moreover, diffusion through the interface was found to drastically enhance the bonding strength from 850°C up to 1050°C. However, excessive grain growth associated to porosity occurrence probably caused the saturation of the bonding strength beyond 1050°C.

TEMPERATURE AND SOAKING TIME CAUSE COLOR CHANGES OF FLEXIBLE DENTURE

Flexible denture is a removable partial denture made of flexible material and can adapt well to the oral tissues. Color stability is one of the basic properties of denture that is needed in achieving good aesthetics. Intrinsic and extrinsic factors can affect the basic denture's color changes. Extrinsic factors can be stain due to the absorption of pigments of dyes from exogenous sources such as denture cleansing solutions, food and beverages, length of use of materials either due to physical or chemical conditions, such as temperature changes. Intrinsic factors include chemical changes in the material itself, among others, due to the imperfect polymerization process, material pollution in the process of making the material or its processing, due to the chemical reaction within the material itself and various processing techniques resulting in the occurrence of porosity on the surface of the material to facilitate the accumulation of dirt. This study aims to observe the color change of the flexible denture base made of nylontermoplastic. The sample of this study used 30 flexible denture base plates measuring 10 mm x 10 mm x 2 mm, soaked at different temperatures of 40 ° C, 50 ° C and 60 ° C for 1 minute, 3 minutes and 5 minutes in each group . The media used is waterbath as a temperature control and then processed using Adobe Photoshop with CIELab method. The results showed significant color changes in the 37 ° C temperature control group with temperatures of 40 ° C, 50 ° C and 60 ° C (p <0.05). Medium between 40 ° C, 50 ° C and 60 ° C has no significant difference (p> 0,05). The conclusion is that the higher of the temperature and the duration of soaking time have a significant effect on the color change of flexible denture.

The Effect of Manganese and Bismuth on the Properties and Behavior of Calcium Phosphate

The human bone contains 70% of calcium phosphate. Calcium phosphates were soared in biomedical research and were approached for a broad range of orthopedic and dental applications. The bioceramic material used in many biomedical applications such as dental and orthopedic application which is the total knee replacement. The main purpose of this work is to study the effect of calcium phosphate when doped with manganese and bismuth. Calcium phosphate ranging from 100 Wt%, 99.65 Wt%, 99.45Wt%, 99.25 Wt%, and 99.05Wt%, manganese constant weight percentage 0.25 Wt%, and bismuth ranging from 0 Wt%, 0.1 Wt%, 0.3 Wt%, 0.5 Wt, and 0.7 Wt%. The green samples were sintered at constant sintered temperature 1300°C. The highest value of density of 4.52 g/cm3 was obtained for CaP 99.25 Wt% doped 0.25 Wt% Mn and Bi 0.5 Wt%. For the shrinkage rate when CaP 99.25 Wt% doped 0.25 Wt% Mn and Bi 0.5 Wt% shrinks 18.20% this was beneficial to know the stronger and higher quality for the material. CaP 99.25 Wt% doped 0.25 Wt% Mn and Bi 0.5 Wt% was able to achieve the highest hardness of 378.3 HV. Maximum young’s modulus of 5.74 GPa was observed for CaP 99.45 Wt% doped 0.25 Wt% Mn and Bi 0.3 Wt% and ultimate compressive strength of 15093.2 N was observed for CaP 99.45 Wt% doped 0.25 Wt% Mn and Bi 0.3 Wt%. SEM image showed no occurrence of porosity for sintered simple at 1300°C and the average grain size was observed is 7.31 um for CaP 99.25 Wt% doped 0.25 Wt% Mn and Bi 0.5 Wt%.

Optimization and comparison of porosity rate measurement methods of Selective Laser Melted metallic parts

The systematic occurrence of porosities inside selective laser melted (SLM) parts is a well-known phenomenon. In order to improve the density of SLM parts, it is important not only to assess the physical origin of the different types of porosities, but also to be able to measure as precisely as possible the porosity rate so that one may select the optimum manufacturing parameters.Considering 316 L steel parts built with different input energies, the current paper aims to (1) present the different types of porosities generated by SLM and their origins, (2) compare different methods for measuring parts density and (3) propose optimal procedures. After a preliminary optimization step, three methods were used for quantifying porosity rate: the Archimedes method, the helium pycnometry and micrographic observations.The Archimedes method shows that results depend on the nature and temperature of the fluid, but also on the sample volume and its surface roughness.During the micrographic observations, it has been shown that the results depend on the magnification used and the number of micrographs considered.A comparison of the three methods showed that the optimized Archimedes method and the helium pycnometry technique gave similar results, whereas optimized micrographic observations systematically underestimated the porosity rate.In a second step, samples were analyzed to illustrate the physical phenomena involved in the generation of porosities. It was confirmed that: (1) low Volume Energy Density (VED) causes non-spherical porosities due to insufficient fusion, (2) in intermediary VED the small amount of remaining blowhole porosities come from gas occlusion in the melt-pool and (3) in excessive VED, cavities are formed due to the key-hole welding mode.

Observations of mechanical and manual forging on bronze as a gamelan material

Gamelan is a traditional musical instrument used by Hindu Balinese in religious and cultural activities. The process of making gamelan begins with the manufacture of copper alloy composition (Cu) and lead (Sn), melting, casting, forging and tone forming by grinding on the surface of the blades. The process of forging on the manufacture of bronze gamelan (CuSn) with an open casting method absolutely must be done because the casting results tend to cause the occurrence of porosity. Porosity that occurs in the bronze as a gamelan material will affect the sound produced. The research conducted is to compare the results of manual forging and mechanical means, where the observations are made on the percentage of deformation that occurs, the density, the hardness and the microstructure of the bronze material. The observations show that mechanical forging provides better mechanical properties, deformation rates, and product microstructure.

In-Process monitoring of porosity during laser additive manufacturing process

This paper describes a deep-learning-based method for porosity monitoring in laser additive manufacturing process. A high-speed digital camera was mounted coaxially to the process laser beam for in-process sensing of melt-pool data, and convolutional neural network models were designed to learn melt-pool features to predict the porosity attributes in deposited specimens during laser additive manufacturing. With the image processing tools developed in this paper, the extraction of porosity information from raw quality inspection data, such as cross-section images and tomography data sets, can be automated. The CNN models with a compact architecture, part of whose hyperparameters were selected through cross-validation analysis, achieved a classification accuracy of 91.2% for porosity occurrence detection in the direct laser deposition of sponge Titanium powders and presented predictive capacity for micro pores below 100 μm. For local volume porosity prediction, the model also achieved a root mean square error of 1.32% and exhibited high fidelity for both high porosity and low porosity specimens.

Influence of processing technology on fracture feature of Ti6Al4V

Selective laser melting is an advanced manufacturing technology providing alternative method of producing complex components directly from 3D computer models. The paper is focused on problems related with selective laser melting technology (SLM) used for preparing titanium based implants. Two series of ten Ti6Al4V samples were mechanically tested in tension and compression respectively before and after heat treatment. Annealing under argon atmosphere consisted of solution treatment at 955 °C followed by furnace cooling to 855 °C with water quenching and ageing at 600 °C with air cooling. Fractography study of fracture surfaces was performed using scanning electron microscopy and the observation was correlated with structural and mechanical properties of the SLM specimens in the condition as-built or heat treated. The failure features of as-built specimens corresponded to the microstructure with relatively high porosity, martensite needles, microcracks and residual stresses. The heat treatment resulted in the transformation of martensite to (alpha + beta) lamellar structure modifying plastic properties that corresponded to the morphology of fracture surfaces. In spite of the porosity occurrence both specimen series exhibited high mechanical properties in tension as well as in compression.

Investigations on dual laser beam welding of aluminum high pressure die castings at reduced ambient pressure

During the manufacture of aluminum high pressure die castings, the aluminum alloy is in a liquid phase during the majority of process steps. Due to the high solubility of hydrogen in liquid aluminum, the die casted part likely has an increased hydrogen content, which affects the weldability negatively. When welding these materials, hydrides dissociate and hydrogen is liberated and forms porosity during solidification. To avoid the described formation of porosity, friction stir welding below the melting point and electron beam welding with high frequency beam oscillation were investigated in prior research. Other studies reported that the formation of porosity during laser beam welding of pure aluminum was prevented by the application of dual beam configurations. However, it is well known that laser beam welding under vacuum condition has several advantages, such as the increase in penetration depth, the enhanced degasification, or the overall calming effect on the melt pool when welding ferrous metals. Aiming to combine these advantages, the current work consequently focuses on the occurrence of porosity during dual laser beam welding of aluminum die castings under vacuum (100–0.1 hPa) and atmospheric conditions. All results are based on the outcome of x-ray computed tomography or tensile testing.

A study of microstructures and mechanical properties of laser welded joint in GH3030 alloy

In this paper, we represent experimental laser welding of GH3030 alloy. The microstructure and mechanical properties of laser welded joints were investigated using an optical microscope, scanning electron microscope, energy diffraction spectrum and other methodologies. The results demonstrated that the weld primarily involved slender dendrites together with a small number of equiaxial crystals. The occurrence of porosities was mainly associated with the composition of the material itself. The cracks in the HAZ were induced by lowmelting- point eutectic phases that formed during laser welding. The segregation of the alloying elements in the matrix induced the variation of the performance within the joint. The average strength of welded joints was 646 MPa, 97.6 % of that of the base metal. Formation of inclusions and micropores in the fusion zone weakened the joint strength greatly.

On the occurrence of weld bead porosity during laser vacuum welding of high pressure aluminium die castings

Due to porosity and incomplete fusion, aluminium high pressure die castings are materials that are known to be difficult to weld. Hereby porosity is mainly caused by hydrogen which is trapped within the weld bead during solidification as a result of insufficient degassing. To enhance degassing and to reduce the influence of surrounding air, laser vacuum welding was applied within the current study. The main goal was to investigate the occurrence of porosity during laser beam welding of aluminium high pressure die castings. To reach this aim, die casting plates were laser welded at varied ambient pressure and investigated by x-ray computed tomography. The analysis of the welds focuses on the size, position, amount and shape of the detected defects depending on the ambient pressure during welding. The results showed a dependency of the occurrence of porosity and the ambient pressure whilst welding.

Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

The laser powder bed fusion (LPBF) or powder-bed additive layer manufacturing process is now recognized as a high-potential manufacturing process for complex metallic parts. However, many technical issues are still to overcome for making LPBF a fully viable manufacturing process. This is the case of surface finish and the systematic occurrence of porosities, which require postmachining steps. Up till now, the porosity origin remains unclear but is expected to be related to the stability of the process. As a LPBF part is made by the accumulation of hundreds of meters of small weld beads, it also appears to be important to understand all the phenomena that occur during the laser-powder-melt pool (MP) interaction for each single track. For this reason, in the first part of our study, using an instrumented LPBF setup and a fast camera analysis (>10 000 image/s), single tracks were fabricated and analyzed in real time and postmortem. Spatters ejections and powder denudation phenomena were observed together with variations of melt pool dimensions and melt-pool instabilities. In turn, the physical origin of this powder denudation and the dynamics of the MP were investigated and discussed.

Use of impedance spectroscopy techniques in the study of corrosion resistance of peel-off aluminum foil lids for the packaging of pureed food

Abstract This work examines the chemical and morphological properties of the different types of aluminum foil lids used for packaging pureed fruit and vegetables (thickness, porosity and type of lacquer applied), their resistance to corrosion when in contact with simulant solutions and influence of the presence of residual air inside food packages. Resistance to corrosion was studied using electrochemical impedance spectroscopy (EIS). In an initial approach focused on quality, this technique was used to determine the protective power of the different types of lacquers and to observe changes in the electrode system over time (storage at 37 °C for three days) with respect to permeability to electrolytes, occurrence of porosity and onset of a corrosive peeling process in the metal substrate. The results of the first accelerated tests carried out in electrochemical cells in air with saline solution, provided a quick, complete feedback on the corrosive behavior of peel-off lids and made it possible to determine the effectiveness of the different lacquering systems considered and the corrosion mechanisms at play. Electrochemical impedance measurements were also carried out in electrochemical cells, which enable the system to be kept in an oxygen-less environment for some time, in order to reproduce the physicochemical conditions that are observed in food packages and in a citric simulant solution with pH 4.0. The cells were stored at a temperature of 37 °C and observed over time for up to 14 days of contact. On the one hand, the results obtained confirmed the different corrodibility of the lid groups examined; on the other hand, they provided information on the commercial life of the packages made with materials that have a good degree of protection. The electrochemical impedance measurements performed with both electrochemical cells show how the value for resistance Rp and capacity Cc registered in the initial phases of the test are fundamental for predicting the corrosion resistance of materials. In conclusion, from the results obtained it was possible to define key physicochemical and electrochemical parameters, such as nature and porosity of the lacquer or presence of additives, to be taken into account in the production of peel-off lids for which aluminum protection is of fundamental importance. The electrochemical tests have provided information on the impedance values needed to ensure the required shelf life for this type of products, recently introduced on the market.

Effect of Porosity on Residual Stress of 2024-Aluminum GTAW Specimen

Aluminum alloys are used widely in many applications due to its low in density which can lead to a lightweight product. A high percentage of Cu in the chemical composition of the 2024 aluminum alloys helps withstand the occurrence of corrosion as well. Thus, aluminum alloy grade 2024 is used as a material for several parts in aircraft and spacecraft components, (e.g. the body of commercial airplanes), as well as parts in many other applications. Gas Tungsten Arc Welding (GTAW) is used widely in joining material parts together. Inappropriate welding parameters usually cause problems such as porosity in the welding. The occurrence of porosity is undesirable in welding because it can affect the strength of the welding area as well as other properties. Tensile residual stress near the surface of the material expedites the fatigue crack initiation. The relationship of porosity and residual stress for GTAW parts was very limited in literatures. Therefore, the objective of this research was to investigate the relationship of porosity to the occurrence of residual stress after the welding process. Full factorial design of experimental technique was used for setting up welding conditions of the GTAW. The specimen with highest porosity was selected for further analysis of its effect on residual stress. Porosity was analyzed by the radiographic testing (RT) and the residual stress was measure by X-ray diffraction (XRD) using sin2 method. The results showed that the highest porosity in the welded bead was found at the current of 130 A, the welding speed of 210 mm./min., and the wire feed rate of 700 mm./min. The results also suggested that lower current and welding speed caused an increase in porosity. The residual stress results on both longitude and transverse directions showed tensile residual stress at locations around the welded bead area.

Fast mass transport of oil and supercritical carbon dioxide through organic nanopores in shale

Hydrocarbon production from shale has grown dramatically in North America, and has the potential to do so globally. Nanoporous organic matter is probably the dominant mode of porosity occurrence in productive shale systems, but the physics of liquid transport through organic-hosted pores is still ambiguous. In the present work, molecular dynamics simulations were conducted to study the static properties and pressure-driven flow behavior of pure liquid hydrocarbons (octane) and supercritical carbon dioxide (scCO2) confined in slit-shaped organic nanopores. Carbonaceous slits having apertures ranging from 1.5 to 11.2nm were explored. A range of thermodynamic conditions, corresponding to the sedimentary reservoirs, were examined. Equilibrium molecular dynamics (EMD) enabled us to determine the density profile, from which we observed the layering structure of confined fluid and the preferential adsorption of scCO2 relative to C8H18 and CH4. As the pore size increases, the structure of the adsorbed phase transforms from a single-file chain to four and three dense monolayers for C8H18 and scCO2, respectively. Then we calculated, using nonequilibrium molecular dynamics (NEMD), their velocity profiles and studied the hydrodynamics under a pressure gradient. We found that the velocity profiles in an organic slit tend to be pluglike, which deviates significantly from the parabolic profile in inorganic nanopores, and the flow exceeds predictions of the no-slip Poiseuille equation by 1–3 orders of magnitude. We proposed two models to characterize the flow behavior, each of which can be integrated into a bottom-up framework to mimic fluid transport in shale and estimate the apparent liquid permeability. The parameters in our models, slip length and apparent viscosity, are exponentially dependent on driving force, pore size, and temperature. Our results, which highlight the need for taking into account the different nature of organic matter and inorganic minerals in flow modeling, will shed light on the development of shale resources and, more generally, mass transfer in nanoporous materials.

Identification of Casting Conditions Influence on the Structure and Properties of Al-Si-X Alloy Castings by Experimental and Virtual Way

The paper describes influence of the structure type and its parameters on the mechanical properties of cast products (not subjected to plastic forming), made out of Al-Si-X alloys. The special attention has been focused on the dendritic structure parameters: dendritic arms spacing of the first order (DAS 1) and the second order (DAS 2). The results of investigations of mechanical properties of the test castings made using three basic casting technologies: gravity sand casting (GSC), gravity die casting (GDC) and high pressure die casting (HPDC), are presented. All the castings were made out of the same AlSi9Cu3 alloy. The test castings (adherent samples and separately cast samples) were subjected to a static tensile test and their mechanical properties were determined. In the next stage, the samples fractures and zones near the fractures (metallographic specimen) were subjected to visual testing, penetrating testing PT and metallographic microscopic tests. The microstructure, including the size of the DAS 2, was determined. Evaluation of the porosity state was also undertaken. A customer casting was also manufactured and subjected to the metallographic, tomographic (CT) and strength tests. The castings solidification simulation tests were performed for all the three casting technologies (GSC, GDC and HPDC) using the Nova Flow &Solid system. The results were used for estimation of the correlation between the cooling rate of the particular casting solidifying in the above mentioned mould types and for the DAS size. The coupled influence of the structure parameters on the mechanical properties, regarding the occurrence of porosity, was also analyzed.

Microstructure and mechanical properties of laser-arc hybrid welding joint of GH909 alloy

In this paper, laser-arc hybrid welding of 10 mm thick low-thermal-expansion superalloy GH909 components was carried out to obtain a joint with good performance. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum and other methodologies. The results showed that weld joints with a desirable wineglass-shaped weld profile can be obtained employing appropriate process parameters. The different grains in between the upper central seam and the bottom seam were associated with the temperature gradient, the pool’s flow and the welding thermal cycle. MC-type carbides and eutectic phases (γ+Laves) were produced at grain boundaries due to the component segregation during the welding process. In addition, γ′ strengthening phase presented in the interior of grains, which kept a coherent relationship with the matrix. The lowest hardness value occurred in the weld center, which indicated that it was the weakest section in the whole joint. The average tensile strength of the joints reached to 632.90MPa, nearly 76.84% of the base metal. The fracture analysis revealed that the fracture mode of the joint was ductile fracture and the main reason for joint failure was as a result of the occurrence of porosities produced in the weld during the welding process.

Numerical Optimization Of The Gating System For An Inlet Valve Casting Made Of Titanium Alloy

AbstractThe main aim of this work was to numerically investigate and optimize feeding and geometrical parameters to produce inlet valves of Ti6Al4V alloy that are free from defects, especially porosity. It was found that the change of geometry orientation as well as inlet feeder diameter and angle showed distinct relationships between geometric alteration and occurrence of porosity. Alteration in the pouring parameters such as temperature and time had none or only slight effect on occurrence or position of porosity in the valve. It was also found that investigating individual parameters of simple geometry and then utilizing these best fit results in complex geometry yielded beneficial results that would otherwise not be attainable.

Influence of ring growth rate on damage development in hot ring rolling

As an incremental forming process of bulk metal, ring rolling provides a cost effective process route to manufacture seamless rings. In the production of hot rolled rings, defects such as porosity can sometimes be found in high alloyed steel, manufactured from ingots having macro-segregation. For the reduction of the waste of material and improvement of product quality, a better understanding of the relations between parameters in the hot ring rolling process and the occurrence of porosity is needed.In this study round bars were used to manufacture rings on an industrial ring rolling mill. Different ring growth rates were applied to investigate the influence on the occurrence of porosity in the final rings. The hot rolled rings were inspected by ultrasonic testing, of which the results were also validated by metallographic investigation.In addition to the experimental investigations, coupled thermo-mechanical multi-stage finite element (FE) analysis was performed with integrated adaptive motion control of the rolls. A damage indicator was implemented in a user-defined elasto-viscoplastic material model. The deformations, stresses as well as temperature history from preform forging were included as initial conditions for the rolling stage. Damage indication from the numerical model matches the experimental result in the considered process conditions.In spite of the suggestion of a more careful process when a low ring growth rate is used in hot ring rolling, experimental and numerical studies demonstrate that with a low ring growth rate there is an increased susceptibility to damage as compared to application of a high ring growth rate.