scholarly journals Shrinkage Porosity in Steel Sand Castings: Formation, Classification and Inspection

2021 ◽  
Author(s):  
Nawaz Mahomed
Keyword(s):  
Shrinkage Porosity ◽  
Process Conditions ◽  
Formation Mechanisms ◽  
Low Carbon ◽  
Porosity Defects ◽  
Casting Cycle ◽  
Engineering Standards ◽  
Steel Castings ◽  
Microscopy Analysis

In this Chapter, shrinkage porosity defects in steel castings are analysed, particularly for low carbon, high alloyed steels, which have applications in critical engineering components. It begins with the mechanisms for porosity formation within the solidification contraction phase of the casting cycle, highlighting the importance of feeder design. This is followed by characterisation of the solidification phase of steel alloys, including the evolution of phases, which is important in distinguishing between microstructure and porosity in microscopy analysis. A more detailed discussion of interdendritic feeding and mechanisms for shrinkage micro-porosity is then provided. This leads to the well-established interdendritic flow model and commonly-used thermal criteria for shrinkage porosity prediction. The discussions are then consolidated through the classification of shrinkage porosity in terms of formation mechanisms and morphology, and its causes relating to composition, design and process conditions. Finally, engineering standards for classification and inspection of porosity types and severity levels in steel castings are discussed. Throughout, basic design and process improvement approaches for improving melt feeding during solidification contraction is given, with emphasis on providing practical solutions for prediction and evaluation of shrinkage porosity defects in castings.

Casting Process Solutions Optimization of LFC Forklift Box

2014 ◽  
Vol 571-572 ◽  
pp. 1091-1096
Author(s):  
Guang Sheng Zhang ◽  
Fei Zhang
Keyword(s):  
Orthogonal Experiment ◽  
Casting Process ◽  
Shrinkage Porosity ◽  
Simulation Software ◽  
Technology Program ◽  
Original Process ◽  
Porosity Defects ◽  
Process Solutions ◽  
Technology Solution ◽  
Casting Simulation Software

There are many advantages in producing forklift box through the LFC. However, we found shrinkage porosity defects in the interior of castings through simulating the original process by ProCAST casting simulation software. Therefore, we analyzed the defects and improved the technology program. firstly, increased riser in position of shrinkage, Secondly, changed the filling’s way, lastly, selected the best temperature and vacuum by the orthogonal experiment and determined the best technology solution. we found the shrinkage porosity defects have been removed by the improved process. We found the production consistent with the simulation results through verification. Therefore we verify the accuracy of the ProCAST.

Simulation on the Thixocasting Process of the Turbocharger Impellers and Selection of the Viscosity Models

2014 ◽  
Vol 217-218 ◽  
pp. 219-224 ◽  
Author(s):  
Fan Zhang ◽  
Xiao Gang Hu ◽  
Da Quan Li ◽  
You Feng He ◽  
Xiao Jing Xu ◽  
...  
Keyword(s):  
Solid Fraction ◽  
High Speed ◽  
High Viscosity ◽  
Shrinkage Porosity ◽  
Die Design ◽  
Semisolid Slurry ◽  
Filling Process ◽  
Viscosity Models ◽  
Defect Control ◽  
Porosity Defects

The thixocasting technology is chosen to produce the turbocharger impellers as it is capable of producing castings with high precision dimension, free of oxide and shrinkage porosity defects and therefore long service life. The thixocasting turbocharger impellers have the similar mechanical property to those produced by forging and machine processes, but much less costs. In the thixocasting process, the semisolid slurry with certain solid fraction is injected into mould at a high speed. Since high viscosity and thixotropic characteristics, the semisolid slurry reveals unique flow condition and characteristics in the filling process. So, its very desirable for the die design, process optimization, and defect control to visualize the high-speed filling process of semisolid slurry by numerical simulation. In this paper, several commonly used viscosity models for semisolid slurry are analysed. The Power law cut-off model (PLCO) model is selected to simulate the filling process in the thixocasting process of the impellers of 319s alloy, compared with actual results by partial filling testing. The causes of the casting defects are also analysed, indicating that the simulation results can accurately reproduce the filling process of semisolid slurry, and PLCO model is a successful choice for simulating the filling process of semisolid slurry with high solid fraction.

scholarly journals Towards low carbon business park energy systems: Classification of techno-economic energy models

Energy ◽  
2014 ◽  
Vol 75 ◽  
pp. 68-80 ◽  
Author(s):  
Jonas Timmerman ◽  
Lieven Vandevelde ◽  
Greet Van Eetvelde
Keyword(s):  
Energy Systems ◽  
Low Carbon ◽  
Energy Models

scholarly journals The Prospects for Reducing the Carbon Footprint in Liquefied Natural Gas Industry

2021 ◽  
Vol 134 (3) ◽  
pp. 3-10
Author(s):  
D. M. Grigoyeva ◽  
◽  
E. B. Fedorova ◽  
Keyword(s):  
Natural Gas ◽  
Carbon Footprint ◽  
World Economy ◽  
Energy Transition ◽  
Liquefied Natural Gas ◽  
Export Market ◽  
Low Carbon ◽  
Gas Industry ◽  
Natural Gas Industry

To meet the terms of the Paris Agreement, it will be necessary to restructure the world economy, make an energy transition to low-carbon development, which will subsequently affect the conventional energy sources industry and, in particular, the liquefied natural gas (LNG) sector. The article provides an overview of the prospects for reducing the carbon footprint in the gas industry. Technical, political and economic measures of decarbonization formation are given. The prospects of the natural gas export market for Russia are outlined. The classification of technologies related to carbon dioxide capture is presented. Special attention is paid to reducing greenhouse gas emissions in the LNG industry.

scholarly journals Early Iron Age Sword from the Territory of the Middle Yenisei

2021 ◽  
Vol 20 (7) ◽  
pp. 135-143
Author(s):  
Oleg A. Mitko ◽  
Sergey G. Skobelev
Keyword(s):  
Iron Age ◽  
Low Carbon Steel ◽  
Morphological Characteristics ◽  
Early Iron Age ◽  
Low Carbon ◽  
North Caucasus ◽  
Group Iii ◽  
The North ◽  
Minusinsk Basin

Purpose. The article is devoted to the characteristics of a double-edged iron sword, which can be attributed to the unique phenomena of the early Iron Age of the Minusinsk Basin. Results. According to its morphological characteristics, the sword is an increased technological modification of the traditional Tagar dagger. The total length of the sword is 59.5 cm; the width of the lenticular blade in cross-section is about 7 cm. The handle with a volute-like pommel is separated from the blade by a narrow butterfly-shaped crosshair. The length of the hilt is 8 cm, which corresponds to the size of the hilts of most Scythian swords. This is a very small size, since in men the average palm width is about 12 cm. Probably, the rounded outlines of the pommel and narrow crosshairs allow, due to their shape, to hold the short handle of a heavy sword more tightly. Conclusion. According to the classification of O. I. Kura, Scythian swords with a narrow butterfly-shaped crosshair and volute-like pommel are included in Group III, Type II A2 dating from the end of the 5th – 4th centuries BC, which corresponds to the boundary between the Podgorny and Saragashen stages of the Tagar culture. The earliest form of sword hilts with typologically similar forms of crosshairs (kidney-shaped, heart-shaped, butterfly-shaped) with bar-shaped pommels appeared in the North Caucasus in the first half of the 7th century BC. On the territory of the Minusinsk Basin, most morphologically similar daggers are usually dated to the 6th – 4th centuries BC. Before the discovery of the Krasnoyarsk sword, long-bladed iron weapons were not known there. At the same time, swords of the Scythian time were found in the nearest regions of Altai and Kazakhstan. The later appearance of the technology for processing iron in the Minusinsk Basin makes it possible to consider the Krasnoyarsk sword an import item. According to another hypothesis, it belongs to the period of the late 3rd – 2nd centuries BC, when local craftsmen mastered the processing of iron and began to make massive quantities of weapons and tools from low-carbon steel. In doing so, they copied traditional archaic forms.

Study on Local Extrusions' Effects on Improvement of Die Casting Prismatic Parts' Forming Quality

2013 ◽  
Vol 312 ◽  
pp. 475-479
Author(s):  
Wei Gang Zheng ◽  
Cun Hong Yin ◽  
Yu Hong Yuan ◽  
Zhen Min Pan ◽  
Chao Tang
Keyword(s):  
Mechanical Properties ◽  
Die Casting ◽  
Casting Process ◽  
Extrusion Process ◽  
Shrinkage Porosity ◽  
Shrinkage Cavity ◽  
Prismatic Parts ◽  
Porosity Defects ◽  
Die Casting Process ◽  
Casting Production

This paper analyzes traditional die casting process to find out the reasons that cause shrinkage cavity and porosity defects in casting. An optimized process of die casting by using local extrusion is proposed. A device used in local extrusion which realizes forcing compensating contraction on key parts of crankcase is designed and the parameters of local extrusion process are discussed. Compared the mechanical properties and microstructure of local extrusion used in die casting production with traditional. It shows that local extrusion used in die casting production can not only achieve the aim eliminating shrinkage porosity and cavity of a casting but also can refine grain to improve the mechanical properties.

Effect of Drying on Porous Characteristics of Orange Peel

2016 ◽  
Vol 12 (9) ◽  
pp. 921-928 ◽  
Author(s):  
Cansu Tamer ◽  
Asli Isci ◽  
Naciye Kutlu ◽  
Ozge Sakiyan ◽  
Serpil Sahin ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Orange Peel ◽  
Sem Analysis ◽  
Shrinkage Porosity ◽  
Process Conditions ◽  
Third Order ◽  
Strong Negative Correlation ◽  
Different Temperatures

Abstract The purpose of the study was to determine the effects of different temperatures (40, 50 and 60 °C) and air velocities (1 and 2 m/s) on shrinkage, porosity, pore size distribution, color and microstructure of orange peel. Empirical models were also proposed to predict shrinkage and porosity as a function of moisture. A strong negative correlation was determined between moisture and shrinkage. Air temperature had no significant impact on the final shrinkage and porosity values. During drying, porosity of the samples first increased until a critical value, at which point further decrease in moisture resulted in collapse of pores. The porosity of the orange peel was correlated with moisture by a third-order polynomial. Pore size distribution curve of raw sample showed two major peaks, a wider and a sharper peak at around 19.8 and 7.18 μm, respectively. After drying, the peaks became shorter and the curve shifted to the left, indicating that the amount of pores and their diameter decreased. The SEM analysis revealed that at extreme process conditions, the orange peel surface was cracked and the characteristic distribution of the waxy components was obstructed.

Methanol carbonylation to acetaldehyde on Au particles supported by single-layer MoS2 grown on silica

2021 ◽  
Vol 34 (10) ◽  
pp. 104005
Author(s):  
Kortney Almeida ◽  
Katerina Chagoya ◽  
Alan Felix ◽  
Tao Jiang ◽  
Duy Le ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Density Functional ◽  
Ostwald Ripening ◽  
Reaction Pathway ◽  
Single Layer ◽  
Process Conditions ◽  
Higher Alcohols ◽  
Low Carbon ◽  
Functional Theory ◽  
Supported Gold

Abstract Homogenous single-layer MoS2 films coated with sub-single layer amounts of gold are found to isolate the reaction of methanol with carbon monoxide, the fundamental step toward higher alcohols, from an array of possible surface reactions. Active surfaces were prepared from homogenous single-layer MoS2 films coated with sub-single layer amounts of gold. These gold atoms formed clusters on the MoS2 surface. A gas mixture of carbon monoxide (CO) and methanol (CH3OH) was partially converted to acetaldehyde (CH3CHO) under mild process conditions (308 kPa and 393 K). This carbonylation of methanol to a C2 species is a critical step toward the formation of higher alcohols. Density functional theory modeling of critical steps of the catalytic process identify a viable reaction pathway. Imaging and spectroscopic methods revealed that the single layer of MoS2 facilitated formation of nanoscale gold islands, which appear to sinter through Ostwald ripening. The formation of acetaldehyde by the catalytic carbonylation of methanol over supported gold clusters is an important step toward realizing controlled production of useful molecules from low carbon-count precursors.

Effect of the chemical composition of 35HGSL steel on shrinkage, casting defects and microstructure

2020 ◽  
pp. 171-179
Author(s):  
М.Л. Скрябин
Keyword(s):  
Chemical Composition ◽  
Heat Removal ◽  
Casting Defects ◽  
Secondary Crystallization ◽  
Cooling Intensity ◽  
Steel Castings ◽  
Investment Models

Стальные отливки на сегодняшний день стали неотъемлемой частью современного литейного производства. В процессе получения отливок неизбежно появляются какие-либо дефекты. В данной работе рассмотрены причины образования дефектов при изготовлении отливок из стали 35ХГСЛ при литье по выплавляемым моделям. Также рассмотрены особенности отвода теплоты от отливки при первичной и вторичной кристаллизации. Приведена классификация зон отливок по ориентации кристаллов в отливках. Выявлена закономерность влияния интенсивности охлаждения на характер усадки. Today, steel castings have become an integral part of modern foundry production. In the process of obtaining castings, any defects inevitably appear. In this paper, we consider the production reasons for the formation of defects in the manufacture of castings made of 35XGSL steel when casting on investment models. The features of heat removal from the casting during primary and secondary crystallization are also considered. The classification of casting zones by the orientation of crystals in castings is given. The regularity of the influence of the cooling intensity on the shrinkage character is revealed.

Effects of Processing Parameters on Microstructure and Properties of Aluminum-Silicon Alloy ADC12

2018 ◽  
Vol 777 ◽  
pp. 300-305
Author(s):  
Kasem Charoenrut ◽  
Chaiyasit Banjongprasert
Keyword(s):  
Mechanical Properties ◽  
Die Casting ◽  
Processing Parameters ◽  
Shrinkage Porosity ◽  
Process Conditions ◽  
Chemical Compositions ◽  
Silicon Alloy ◽  
Aluminum Silicon Alloy ◽  
Casting Pressure ◽  
Aluminum Silicon

Aluminum-Silicon Alloy, ADC12 is one of the most popular alloys for pressure die casting due to its high castability and high productivity. ADC12 is a hypoeutectic aluminum-silicon alloy that contains 10-12wt% of Si and has an occasional problem for a mechanical properties failure such as crack and shrinkage porosity. This study presents the investigation of the microstructure of ADC12 parts produced by pressured die casting with different process parameters and chemical compositions. The microstructure was observed using optical microscopy (OM) and scanning electron microscopy (SEM) with energy – dispersive X-ray (EDX) and electron backscatter diffraction (EBSD) to determine phases, grain, and crystallographic information in order to understand the microstructural evolution after die casting with different process conditions. Changes in casting pressure and a reduction of iron content contributed to enhanced mechanical properties and less shrinkage porosity. This was due to different processing parameters, mainly casting pressure. The average grain size of aluminum matrix was also reduced due to a higher pressure during casting with a moderately fast cooling rate.

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