Influence Of Casting Parameters Research Articles

A Numerical Method to Study the Fiber Orientation and Distribution of Fiber-Reinforced Self-Compacting Concrete

Steel fiber-reinforced self-compacting concrete (SCFRC) has been developed in recent decades to overcome the weak tensile performance of traditional concretes. As the flexural strength of SCFRC is dependent on the distribution of steel fibers, a numerical model based on Jeffery’s equation was developed in this study for investigating the effects of the concrete flow on the fiber orientation and distribution in SCFRC. This numerical method shows higher computational efficiency than available particle-based methods like SPH and LBM. The influence of casting parameters like casting method, formwork size and casting velocity on the fiber orientation is investigated from the perspective of the flow field of fresh concrete during casting. The simulation results show that the fiber orientation is largely dominated by the concrete flow during the casting process. Importantly, during casting SCFRC beam, fibers tend to be oriented in parallel along the longitudinal direction at the middle section, while they stick up at the end of the formwork due to the upward concrete flow. In addition, the results from parametric studies show that the formwork size and casting method could significantly affect the concrete flow during the casting process, ultimately the orientation of fibers in a SCFRC beam. Furthermore, it indicates that the casting speed needs to be carefully chosen in order to achieve the optimal fiber alignment.

Development of new layered compression casting approach for concrete

Compression casting is a highly effective approach for improving the performance of normal concrete significantly without any additional material/chemical and extra costs. The technology is suitable for manufacturing precast concrete members. However, compression casting of full-scale structural members like beams and columns is challenging due to the high compression pressure required and the limitations of the load-bearing capacity of mould and casting facilities. This study proposes a Layered Compression Casting (LCC) method to overcome the aforementioned problems. For this reason, the influence of casting parameters, including compression pressure P, height of casting layer H, compression duration T, cement content C, water to cement ratio W/C, and Recycled Aggregates (RA) dosage, on the compressive strength, peak strain, elastic modulus, and stress-strain behavior of LCC concrete is investigated. The results reveal that the compressive strength and modulus of elasticity of LCC concrete are significantly improved compared to traditional concrete (up to almost 100% and 50%, respectively). Based on the results obtained from this study and considering compression casting efficiency, the following optimum LCC parameters are recommended: H = 300 mm, P = 15 MPa, and T = 2 min. Furthermore, empirical models are developed/evaluated to predict the compressive strength, peak compressive strain, elastic modulus, and stress-strain relationship of the LCC concrete.

INFLUENCE OF CASTING PARAMETERS ON FATIGUE PROPERTIES OF THE ŻS6U-WI ALLOY

The hot parts of aircraft engines are made of nickel-based superalloys and work in extremely difficult conditions. The compressor blades mentioned in the article are usually produced by a casting process whose parameters have a great influence on the fatigue properties of the end product. The parameters of the casting process have significant influence on the microstructure, i.e. phase components morphologies. The article presents the results of the analysis of microstructures of nickel superalloys and the influence of casting parameters on the fatigue strength of finished products. The casting parameters were selected experimentally. The work included analysis of the microstructure of semifinished products and high-cyclic fatigue strength tests of the final product.

Mathematical Modeling on the Influence of Casting Parameters on Initial Solidification at the Meniscus of Slab Continuous Casting

In the current study, the two-dimensional mold model was applied to investigate the influence of different casting parameters on the initial solidification at the meniscus of the continuous casting mold. The profile of the meniscus and the slag rim, and the heat flux on the hot face of the copper plate, were compared with different locations of the mold and different casting parameters. The depth of the oscillation marks and solidified meniscus through simulation was measured with different casting parameters. With the mold oscillating downward from the peak to the valley, the maximum heat flux on the hot face of the copper plate near the meniscus increased from 4.3 to 5.5 MW/m2, the thickness of the slag rim decreased from 4.7 to 4.2 mm, and the height of the curved meniscus also decreased. With the increase of casting speed from 1.2 to 1.45 m/min, the maximum speed of the upper backflow increased from 0.6 to 0.8 m/s, and the lowest location of the meniscus at approximately 310 mm from the copper plate decreased from 22 to 12 mm below the meniscus near the nozzle, where the slag entrapment easily occurred. With the increase of the casting speed, casting superheat, and oscillation frequency, and the decrease of the water flow rate in the mold and oscillation amplitude, the thickness of the slag rim decreased. With the increase of casting speed and superheat, and the decrease of the water flow rate in the mold, oscillation frequency, and oscillation amplitude, the depth of the solidified meniscus decreased. The regression equation was fitted to estimate the depth of hooks at the subsurface of slabs.

Mathematical Modeling of Initial Solidification and Slag Infiltration at the Meniscus of Slab Continuous Casting Mold

In the current study, a mathematical model was established to investigate meniscus solidification and slag infiltration in the mold. The model considered the two-dimensional steel-slag-air three-phase fluid flow, heat transfer, solidification of the steel and mold oscillation. The calculated solidification shell was compared with measured hook lines to validate the model. The initial solidification and slag infiltration at the meniscus were revealed during an oscillation cycle. The influence of casting parameters on initial solidification was studied. Through simulations, the liquid slag flowed into the gap between the steel shell and copper plate during the positive strip stage, while it flowed out of the gap during the negative strip stage. The solidification depth of the meniscus from the solidification tip to the inner mold face reduced with the increase of casting temperature and casting speed and the decrease of water flow rate in the mold and oscillation amplitude.

Influence of Casting Parameters on Hooks and Entrapped Inclusions at the Subsurface of Continuous Casting Slabs

In the current study, several layers beneath the surface of ultra-low carbon steel continuous casting slabs were inspected to investigate non-metallic inclusions, and then faces vertical to the surface of the slab were etched to reveal hooks. The influence of casting parameters on hooks and the entrapment of inclusions by hooks was investigated. Most > 100 μm inclusions were found to be located within 0.5 to 3.5 mm beneath the surface of the slab. Leaf-like hook, double-hook, and truncated hooks were observed, and bubbles and inclusions were found to be located below hooks. With the increase of the cooling water flow rate in copper plates of the continuous casting mold from 5300 to 5940 L/min, the average depth of hooks at the edge of narrow face increased from 1.37 to 1.53 mm, the number of > 20 μm inclusions increased from 1.6 to 2.6 per 100 mm2, and the average size of > 20 μm inclusions increased from 25.1 to 31.8 μm. With the decrease of the casting temperature from 1573 °C (1846 K) to 1549 °C (1822 K), the average depth of hooks at the edge of narrow face increased from 1.24 to 2.01 mm, the number of > 20 μm inclusions increased from 2.0 to 6.0 per 100 mm2, and the average size of > 20 μm inclusions increased from 26.0 to 27.0 μm. Hence, the surface defect of the rolled steel plate could be improved by lowering the depth of hooks at the subsurface of continuous casting slabs.

Experimental Investigation on the Effect of Casting Parameters on Thin walled Castings of Metal Matrix (LM21-SiC) Composite

 Metal matrix composites (MMCs) are widely used in several applications owing to their high strength, high specific stiffness, greater wear resistance and light weight. Normally, MMCs are processed through stir casting which exhibits poor wet ability and bonding between metal matrix and ceramic reinforcement, porosity and hot tears. These drawbacks can be overcome by squeeze casting process. Here an attempt was made on processing LM21-Sic composite for making hollow casting through squeeze casting process. Four process parameters are chosen namely squeeze pressure, stirring speed, melt temperature and reinforcement percentage. The primary objective was to experimentally investigate the influence of casting parameters on hardness & wear. Samples were cast for each experiments condition based on L9 orthogonal array. From the analysis of variance (ANOVA), it was observed that stirring speed, reinforcement percentage and Squeeze load were the process parameters making a noticeable improvement in hardness and wear. The mechanical properties such as hardness and wear are evaluated and optimum casting condition was obtained.

Modeling and Analysis for Hardness and Structure of Nonferrous Alloy Castings Produced Using Zcast Metal Casting Process through Response Surface Methodology

The purpose of this investigation is to develop a mathematical model for predicting the influence of casting parameters on hardness of non ferrous alloy (NFA) castings produces using Zcast process by employing response surface methodology (RSM). An association has been proposed between hardness of castings and shell wall thickness (SWT), weight density (WD) and pouring temperature (PT) of the shell mould fabricated using three dimensional printer (3DP). The experiments were conducted using NFA materials like; aluminium, zinc, lead, copper, brass and bronze. An effective procedure of RSM has been utilized for the optimal values of casting parameters. Mechanical Micro-Vickers hardness was measured in which the indent is produced by applying a known load to the specimen and then measuring the size of the appropriate diagonals optically. Based on experimental data the investigation has led to conclusion as Quadratic model have been established for predicting the response in the form of hardness of castings.Further, the model developed was validated by analysis of variance (ANOVA) which indicated the significance of model. The Model F-value of 2477.66 implies that the model is significant. There is only a 0.01% chance that a Model F-Value could occur due to noise. Values of "Prob > F" less than 0.05 indicate model terms are significant. The statistical analysis of second order quadratic equation results showed that the most significant parameters, favoring the hardness are B, C and A2. The superiority of the quadratic mathematical models were developed in confidence intervals of 99.75% with prediction error sum of squares of 3.6%for the prediction of the harness.Microstructure analysis was also performed for justification of hardness data.

Simulation of stray grain formation during unidirectional solidification of IN738LC superalloy

The influence of casting parameters on stray grain formation of a unidirectionally solidified superalloy IN738LC casting with three platforms was investigated by using a 3D cellular automaton-finite element (CAFE) model in CALCOSOFT package. The model was first validated by comparison of the reported grain structure of Al-7%Si (mass fraction) alloy. Then, the influence of pouring temperature, heat flux of the lateral surface, convection heat coefficient of the cooled chill and mean undercooling of the bulk nucleation on the stray grain formation was studied during the unidirectional solidification. The predictions show that the stray grain formation is obviously sensitive to the pouring temperature, heat flux and mean undercooling of the bulk nucleation. However, increasing the heat convection coefficient has little influence on the stray grain formation.

A 3-D Mathematical Model of Thermal Field Evolution in the Direct Chill Casting of Superlight Magnesium Alloy Slabs

A mathematical model of the direct chill (DC) casting process for superlight Mg-Li alloy (LA141) slab has been developed using the finite differential method (FDM). Thermal boundary conditions including primary and secondary cooling conditions have been selected based on knowledge of the physical process and the literatures. The variations of heat transfer coefficient between slab and dummy block interface resulting from the deformation of the slab have been considered. By calculating the temperature distribution, solid-liquid interface shape and position, the influence of casting parameters on DC casting process, such as the pour temperature, cooling water flow rate and casting speed have been analyzed. Moreover the profiles of the solidification fronts during the casting processes for the alloys of LA141 and AZ31 are compared.

Influence of casting parameters on void volume and centre segregation in continuously cast 100Cr6 blooms

Continuously cast ball and roller bearing steel 100Cr6 exhibits comparatively strong segregation which poses a quality handicap. In the present work which was carried out in the time between 1992 and 1996 the void formation which is related to the centre segregation and the centre segregation were measured on 2 m long segments of 240 × 200 mm2 blooms cast at the steel plant of Georgsmarienhütte GmbH. It was found that the segregation of carbon expressed with the ratio of Cmax/Co increases with casting speed and superheat. Many experiments were carried out to elucidate the effect of electromagnetic stirring along the lower part of the metallurgical length (F-EMS). But, unfortunately, a decrease in segregation could not be achieved by F-EMS. The only method to decrease the centre segregation in continuously cast blooms of 100Cr6 seems to be casting at low speeds with low superheat.

Novel porous poly (vinylidene fluoride) membranes for membrane distillation

Polyvinylidene fluoride (PVDF) membranes were prepared by water immersion of a binary PVDF-solvent solution cast on the outer surface of a porous tubular support. During immersion the free shrinkage of the cast solution was hindered by the support and consequently the nascent membrane was subjected to a stretching action that caused pore formation. A laboratory scale device was realized for casting operation and some preparative parameters were studied to control the deposition of the PVDF solution on the porous support. Membranes were characterized through scanning electron microscope observations, air permeability measurements, ultrafiltration tests and membrane distillation experiments. These latter were carried out with a laboratory unit fed with 3 w/v% aqueous NaCl solution at 69°C. The membranes were housed in a tubular cell with the feed flowing on the shell side and the sweeping air in the membrane lumen. The effect of feed and gas velocity on the membrane performance was investigated and the obtained results were compared with those of commercial tubular membranes tested on the same unit. The influence of casting parameters on the morphology and permeation properties of the membranes was also studied.

Investigation of mould thermal behaviour by means of mould instrumentation

The thermal behaviour of the continuous casting mould has a critical influence on strand surface quality, casting productivity and operating safety. voestalpine Stahl GmbH has long been interested in the field of research into mould behaviour, and began with the investigation of heat flux in 1995, and then of thermal variability in 1999. Since 2000, an online mould thermal monitoring system for heat flux density, thermal variability and friction has been installed. The heat flow density in the mould is determined by measuring the inflow and outflow temperatures and the throughflow volume of the primary cooling water. Temperature as measured by a thermocouple based breakout detection system in the mould copper plate is used to investigate the thermal variability. These online measured values have been employed to examine the influence of casting parameters, steel analysis and casting powder on the heat flux and thermal variability, and the relationship between these variables and cracking. The knowledge gained through these wide ranging plant based investigations has been used as a major tool in the diagnosis of problems (such as breakout and sticking), for optimisation of the process, particularly in the field of casting powders, and for control of slab quality. In particular, this knowledge has been incorporated into online mould thermal monitoring.

Microstructural evolution on continuous casting of nickel based superalloy Inconel* 713C

In the present work, the evolution of microstructure in the nickel based superalloy Inconel 713C was investigated for the vertical continuous casting of small cross-section rods (10 mm dia.), using several microstructural characterisation techniques. Microstructural evolution was greatly affected by the mould design, average casting speed, and distance from the rod surface, but the strongest influence was from the alternating drawing mode consisting of the drawing stroke, the resting period, and the reverse stroke, which caused periodic orientation changes of columnar γ crystal grains. Combined with other casting parameters this determined the local solidification conditions, influencing the formation and growth of γ dendritic grains and primary and eutectic MC carbide, as well as the stress distribution in the solidified shell, which caused shell deformation and the appearance of the inverse segregation and, occasionally, hot tears. A physical model is presented to explain the influence of casting parameters on microstructural evolution on the continuous casting of this alloy.

An analysis of shrinkage defects in aluminium and aluminium-copper castings

The influence of casting parameters and alloy composition on the formation of shrinkage defects has been studied using a T-piece test casting. Macro shrinkage defects were found in pure aluminium and aluminium 0.4wt% copper castings, but not in aluminium 1, 2, and 4.5 wt.% copper alloys. The thermal data which were in general, reproducible to +/-5% showed that a negative temperature gradient prevailed in the pure and aluminium 0.4wt% aluminium alloy right up to the end of freezing. In the aluminium 1, 2 and 4.5 wt.% copper alloys the initial negative gradient changes to become positive after approximately one half of the total solidification time has elapsed. The gradient was only of the order of 2°C/mm. Variations in pouring temperature of about 50°C and filling times of a factor of three changed the solidification times by 10% only. Such variations did not change the relative freezing times at different locations in the uniform section castings. Solidification times for the 15 mm horizontal section of the castings (a/b = 0.6) were similar to those of the 25 mm sections (a/b = 1) showing that even in this simple case the modulus concept is invalid. The form of the cavities in the feeder heads is a function of the metal cast, the gas content and the grain structure. The results formed the basis of validation tests for a computer shrinkage model.**

A Study of the Bearing Characteristics of Zinc-Aluminum (ZA) Alloys

AbstractBearing design studies have been conducted using Block on Ring and full bearing test techniques. The Block on Ring testing provided a rapid first order evaluation of a variety of zinc, bronze and aluminum alloys, produced by different casting processes. Full bearing tests were conducted on continuously cast and sand cast ZA-12, ZA-27 and lead-tin bronze.The study showed the sand cast ZA-27 alloy to have equivalent wear resistance to C95200 aluminum bronze and A828.0 aluminum-tin alloys and superior wear resistance to C93200 lead-tin bronze. The influence of casting parameters and journal conditions on bearing performance at low to high loads has been precisely established. The best overall performance was shown by the ZA-27 alloy combined with a hardened (Rc 40–45) journal of roughness 0.4–0.6 μm CLA. The wear rate was found to be related directly with overall hardness of the bearing material and, for the zinc alloys, the amount of copper rich e(CuZn4) phase present in the microstructure.

A Study of the Bearing Characteristics of Zinc-Aluminum (ZA) Alloys

Bearing design studies have been conducted using Block on Ring and full bearing test techniques. The Block on Ring testing provided a rapid first order evaluation of a variety of zinc, bronze and aluminum alloys, produced by different casting processes. Full bearing tests were conducted on continuously cast and sand cast ZA-12, ZA-27 and lead-tin bronze.The study showed the sand cast ZA-27 alloy to have equivalent wear resistance to C95200 aluminum bronze and A828.0 aluminum-tin alloys and superior wear resistance to C93200 lead-tin bronze. The influence of casting parameters and journal conditions on bearing performance at low to high loads has been precisely established. The best overall performance was shown by the ZA-27 alloy combined with a hardened (Rc 40–45) journal of roughness 0.4–0.6 μm CLA. The wear rate was found to be related directly with overall hardness of the bearing material and, for the zinc alloys, the amount of copper rich ε(CuZn4) phase present in the microstructure.