Wall Thickness Of Casting Research Articles

The Formation of the Strength of Castings including Stress and Strain Analysis.

This article presents some views on the subject of self- or residual stresses, trying to clarify some erroneously seemingly ingrained formulations in the introduction, which are widely used in castings and their classification (thermal, shrinkage, and phase stresses). For example, the location of their occurrence is often not specified, nor in which cross sections (volumes) they balance. In thin bars there are uniaxial stresses and in thin plates, stresses in two orthogonal directions are considered, while in castings, which are always three-dimensional objects, stresses in all planes should be considered. Meanwhile, to make matters worse, the complexity of calculations and possible experiments is rapidly increasing from the 1-axis to the 3-axis condition. A detailed analysis is made of how tensile and compressive stresses are calculated as a function of casting wall thickness, taking into account heat flow between walls of different thicknesses. The article presents selected methods of stress and strain testing, with particular emphasis on elasto-optical testing.

Influence of the Cooling Rate on Mechanical and Corrosion Properties of Ferritic Si–Mo Ductile Cast Iron

In this study, the effect of the cooling rate controlled by different castings thickness ranging from 3 to 25 mm on the mechanical and corrosion behavior of Si–Mo ductile iron (DI) castings was investigated. SEM-EBSD investigations demonstrated that the nodule counts, nodularity, and ferrite phase increased while the ferritic grain size decreased with decreasing in the casting wall thickness; this in turn led to improvements in the tensile properties of the DI. The corrosion behavior of Si–Mo DI castings was investigated after different immersion times in a 3.5 wt pct NaCl solution via electrochemical experiments. The electrochemical results showed that the corrosion resistance of Si–Mo DI decreased in the following order: 3 > 5 > 13 > 25 mm. The results indicated that all of the tested DI samples exhibited galvanic corrosion between the nobler carbide and ferritic matrix phases. SEM analysis showed that the dissolution of the ferrite phase with the pearlite phase exposed and accumulated on the DI’s surface, which led to intense corrosion acceleration. The higher corrosion rates that were observed for those samples with higher casting wall thicknesses could be associated with the higher contents of pearlite/carbide.

Reserves of resource saving in the manufacture of brake drums of cargo vehicles

The object of research: cast iron grade DSTU EN 1561 (EN-GJL-200), used for the manufacture of brake drums for KrAZ trucks.
 Investigated problem: obtaining the effect of resource saving by minimizing the consumption of alloying elements, while maintaining a given level of mechanical properties of cast iron.
 The main scientific results: experimental and theoretical confirmation of the possibility of reducing the content of Cr introduced into the alloy to increase its strength, as part of the Cr:Ni alloying complex, was obtained. It is shown that a decrease in the Cr content from the upper range (0.34–0.48) % to the lower one (0.21–0.33) % does not affect the ultimate strength of cast iron (σb). The obtained values of σb for both ranges are statistically equal: σb =234MPa, Sσb =16.22 MPa for the upper range of Cr content and σb=240MPa, Sσb=19.86 MPa for the lower range of Cr content, where Sσb is the standard deviation of the tensile strength value. It is established that the hardness (HB) is also unchanged: the obtained values of HB for both ranges are statistically equal: HB213, SHB=9.1 for the upper range of Cr content and HB212, SHB=12 for the lower range of Cr content, where SNB is the standard deviation of hardness. At the same time, it has been statistically proven that the Cr:Ni ratio can be shifted towards lower Cr values – from Cr:Ni=2.2:1 in the existing technology to Cr:Ni=1.76:1 in the ones proposed in this study.
 The area of practical use of the results of the study: the results obtained can be used in machine-building enterprises specializing in the manufacture of hull cast iron parts with a foundry cycle. The adaptation of the proposed results to the actual conditions of the foundry production of implementing organizations will be minimal if they comply with the following criteria: cast iron grade, predominant or minimum casting wall thickness, temperature regime of melting and out-of-furnace treatment, ferroalloys and modifiers used.
 Innovative technological product: iron smelting technology for commercial vehicle brake drum castings that reduces production costs while maintaining a given level of mechanical properties
 The scope of the technological innovative product: technological regimes for producing cast iron for the production of cast brake drums for trucks.

Effect of Micro-Structural Dispersity of SiMo Ductile Iron on High Temperature Performance during Static Oxidation

High silicon and molybdenum (SiMo) ductile iron is commonly used for car exhaust systems, and its micro-structural dispersity depends on intrinsic parameters, which include alloy composition and inoculation efficiency, as well as extrinsic factors, such as casting wall thickness and molding material, which define cooling rate during solidification. Micro-structural dispersity is referred to as the degree of heterogeneity of sizes of structural constituencies within the microstructure. A variation in the micro-structural dispersity could impact the high temperature performance of SiMo ductile iron during static oxidation and transient thermo-mechanical loading conditions. In this study, static high temperature tests were performed on SiMo ductile iron solidified in a casting with varying wall thicknesses from 5 mm to 100 mm. The faster solidified specimens (taken from near chilled casting surfaces) had extremely high micro-structural dispersity as compared to the thicker section samples. After thermal exposure, each of the samples were characterized using 2D sections and 3D µCT images, and the results indicated an order of magnitude difference in graphite phase dispersity. The surface degradation was quantified after static oxidation experiments were implemented at temperature intervals between 650 °C and 800 °C. Non-destructive µCT 3D analysis and SEM/EDS were performed on cross sections and used to quantify the scale topology and structure. Carbon analysis was used to decouple the scale formation and decarburization phenomena that occurred within the samples. These methods enabled the quantification of the oxidation of the SiMo cast iron with different micro-structural dispersity levels after being exposed to high temperature static oxidation. Additionally, the complex material behavior during oxidation-assisted transient thermo-mechanical loading will be presented in a separate article.

The Role of the Primary Structure in the Formation of the Mechanical Properties of Steel Castings

The paper considers the total effect of primary structure parameters on steel mechanical properties depending on the wall thickness of castings. It is shown that during the formation of mechanical properties with an increase in the thickness of the work-piece, the role of the sizes of primary grains decreases and the role of reducing the dispersion of dendritic crystals increases, due to the process of dendritic branches coarsening.

Weight Optimization of Housing Bracket for Electrical Starter Motor using FEA

Starter motor is an electric motor which provides electro-mechanical motion to start the internal combustion engine. The electric starter ensures that anyone could easily start and run an internal combustion engine for any passenger vehicles. Starter motor housing bracket strength and weight has been continuously a concern which may lead to operational cost high and durability life. The important causes of higher weight gain are overdesign, customer demand, casting feasibility and the operating conditions. This paper presents the design optimization methods for robust design to meet the product weight and fatigue life cycle requirements considering the manufacturing feasibilities of casting wall thickness and draft allowances with metal flow radius for the starter operating conditions. In the optimization of housing bracket, finite element analysis software was used for calculating the stress and fatigue life and then the weight was optimized. The optimized new housing bracket was proposed for new starter projects to capture new business and the design was implemented to reduce cost in productionized starters.

High-quality manufacturing method of complicated castings based on multi-material hybrid moulding process

A multi-material hybrid patternless moulding process for complicated castings has been proposed. Moulding sands used in the hybrid moulding process include silica sand, ceramic sand, chromite sand, zircon sand, and steel shot sand. Experimental method was used to study the effects of moulding sands on the temperature field, mechanical properties, and dimensional precision of the iron castings. Under the condition that the wall thickness on different sides of the casting is the same, when the wall thickness is greater than 10 mm, the heat storage capacity of the moulding sands from strong to weak is steel shot sand, zircon sand, chromite sand, ceramic foundry sand, and silica sand. Tensile strength of the obtained castings from high to low is zircon sand, chromite sand, steel shot sand, ceramic sand, and silica sand. Contraction rate of the obtained castings from high to low is steel shot sand, zircon sand, chromite sand, silica sand, and ceramic sand. Therefore, steel shot sand and zircon sand can be used as chilled sand, and even can be used instead of cold iron when the casting wall thickness is greater than 10 mm. Zircon sand and chromite sand can be used to obtain high mechanical properties, and silica sand and ceramic sand can be selected to obtain high dimensional precision of the castings. Finally, a typical iron casting piece was tested by experiment using the hybrid moulding process. Excellent performances of iron castings confirm the feasibility of the hybrid moulding process.

Influence of variable casting wall thickness and shell mold material and its thermal properties on secondary dendrite arm spacing in IN 713C superalloy castings

Influence of variable casting wall thickness and shell mold material and its thermal properties on secondary dendrite arm spacing in IN 713C superalloy castings

Effect of mould sand type and casting wall thickness on properties and microstructure of multivariate Al–7·5Si–4Cu alloy

The effects of different mould sands and casting wall thicknesses on the properties and microstructures of multivariate Al–7·5Si–4Cu alloy, which was modified by Al–10Sr, RE and Al–5Ti–B master alloys, were investigated. The melt was poured into multistep moulds made from three mould sands (quartz, alumina and chromite) to produce specimens for mechanical property testing and metallography. The results demonstrated that the sample with chromite sand exhibited the best mechanical properties owing to its higher cooling rate. Tensile strength and elongation decreased monotonically with increasing wall thickness. No obvious trend of wall thickness on hardness of the alloy was found. When the cooling speed decreased, the grain refinement and transformation effect became weaker, the dendrite arm spacing (DAS) increased obviously and the properties and microstructures became poorer. A series of fitting models was established and used to predict properties of Al–7·5Si–4Cu alloy from the DAS.

Filling Characteristics of Magnesium Alloy Molten Metal in Squeeze Casting

Based on fluid mechanics, the filling process of magnesium alloy step-plate casting molten metal was analyzed, and the filling characteristics were studied by numerical simulating. The results show the filling velocity and the wall thickness of casting have a great effect on the filling characteristics of magnesium alloy. When the filling velocity is less than 0.3 m/s, the liquid frontier of molten metal and the fluid level of thick upper surface fluctuate greatly, and the defects of air entrainment and oxide impurities will appear. When the filling velocity is more than 0.58 m/s, the molten metal fills in turbulent way, and the defects of sputter and air entrainment will appear. The correlation between the wall thickness of casting and the critical filling velocity presented in this paper can be used for the optimization of filling velocity.

Microstructure, fluidity, and mechanical properties of semi-solid processed ductile iron

This research is directed towards studying the effect of semi-solid processing (using cooling plate tech- nique) on the microstructure, fluidity, and mechanical properties of ductile iron (DI). Sand mold castings with constant width of 25 mm and length of 150 mm with the thicknesses of 6, 12, 18, and 25 mm were used in this study. Microstructure, fluidity, and tensile strength prop- erties were investigated as a function of fraction of solid. The results indicated that by increasing fraction of solid microstructure becomes finer and more globular. However, increasing primary fraction of solid increases the cementite content in the matrix. Above a certain fraction of solid (fs = 0.28, fs = 0.1, and fs = 0.05 for 25, 18, and 12 mm wall thickness, respectively), the fluidity of semi-solid processed DI decreases steeply. For low fraction of solid (fs B 0.15), increasing the fraction of solid results in an increment in the tensile strength, comparing with the ordinary DI due to the fine and globular structure forma- tion. Any further increment of fraction of solid (fs ( 0.15) leads to the cementite increment and gas porosity forma- tion, consequently the tensile strength decreased. The fraction of solid of DI and casting wall thickness should be considered in order to obtain the best combination of microstructure, fluidity, and mechanical properties of semi- solid processed DI.

Hollow castings produced by interrupted low pressure die casting

Hollow aluminium castings have been produced by low pressure die casting where the pressure has been released when only a shell has solidified, thereby draining the liquid out of the centre of the casting. The influence of holding time of the melt in the die, the die temperature and the alloy type on the thickness and quality of the solidified shell has been investigated. It has been found that hollow castings can be produced reproducibly with constant wall thickness under constant process conditions. The casting wall thickness increases linearly with pressure holding time. The die temperature has less influence on the wall thickness. The roughness of the inner surface of the castings varies with alloy type. An Al–12 wt-%Si (AlSi12) alloy gives a very uneven rough inner surface whereas an Al–5 wt-%Mg (AlMg5Si) alloy gives a smooth, even surface. Grain refinement also improves the surface quality. Attempts to predict the wall thickness with a commercial casting software package had limited success; the calculations seem to overestimate the thickness.