The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism
of decohesion – the intergranular one – occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking
initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence
of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite
precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage
solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C
revealed low or very low strength of high-carbon cast steels.
In general, uniform mixing of particles is desirable in the process of particle handling. However, during the charging of sinter feed and upper ore, size segregation must be induced to prevent heat imbalance, ensure bed permeability, and prevent the loss of fine ore. In this study, upper ore charging was simulated using a discrete element method (DEM) to find the optimal method for controlling particle size segregation, and the segregation characteristics in the upper ore bed were investigated when a deflector plate was applied to the charging machine. The degree of vertical segregation increased when a deflector plate was applied, and it was confirmed that the segregation direction in the upper ore bed can be controlled by adjusting the charging direction of the upper ore by using a deflector plate. In order to apply this method directly to the actual process, further study is needed to understand the influence of the characteristics of the deflector plate such as length and angle.
Waste management is a challenging problem for most of the countries. The current waste segregation and the collection method are not efficient and cost-effective. In this paper, a prototype is presented for smart waste management. It is also capable of waste segregation at the ground level and providing real-time data to the administrator. Impact and cost analysis of the deployment of smartbin is also presented considering one ward of Ahmedabad Municipal Corporation. It is clear from that deployment of this smartbin will save about 40% of the current expenditure for that ward.
The paper presents the possibility of application of the developed computer script which allows the assessment of non-equilibrium
solidification of binary alloys in the ThermoCalc program. The script makes use of databases and calculation procedures of the POLY-3
module. A solidification model including diffusion in the solid state, developed by Wołczyński, is used to describe the non-equilibrium
solidification. The model takes into account the influence of the degree of solute segregation on the solidification process by applying the
so-called back-diffusion parameter. The core of the script is the iteration procedure with implemented model equation. The possibility of
application of the presented calculation method is illustrated on the example of the Cr-30% Ni alloy. Computer simulations carried out
with use of the developed script allow to determine the influence of the back-diffusion parameter on the course of solidification curves,
solidus temperature, phase composition of the alloy and the fraction of each phase after the solidification completion, the profile of solute
concentration in liquid during solidification process, the average solute concentration in solid phase at the eutectic temperature and many
other quantities which are usually calculated in the ThermoCalc program.
The article presents the results of investigations performed on segregation of elements in the billets. The research were performed under standard industrial conditions, during high carbon steel production cycle. Probes (templates with the thickness of 20 mm) were taken from billets with square cross-section of 160 mm. Segregation of elements was determined based on the quantitative analysis of results performed by using spark spectrometry pursuant to PN-H-04045. Changes in concentrations of elements were analysed along two cross-sections. Element contents were performed at points distanced from each other by approx. 10 mm. The segregation of carbon, sulphur and phosphorus was determined for different billets.
This study investigates the microstructures and the mechanical properties of equiatomic Ti20Mo20Ta20Nb20V20 and non-equiatomic Ti40Mo15Ta15Nb15V15 and Ti60Mo10Ta10Nb10V10 HEAs using X-ray diffraction (XRD) analysis, field emission scanning electron microscope (FE-SEM), and micro-Vickers hardness test. The specimens were fabricated using the vacuum arc remelting (VAR) process and homogenized at a temperature of 1300°C for 4 h in a vacuum atmosphere. The determined thermodynamic parameters, Ω ≥ 1.1, δ ≤ 6.6%, and VEC < 6.87, suggested that the HEAs consisted of BCC solid solutions. XRD patterns of all the HEAs displayed single BCC phases. The difference in the solidification rate led to the micro-segregation associated with the elements Ta and Mo enriched in the dendrite arms and the elements V and Ti in the inter-dendritic regions. The HEA specimens showed a decrease in hardness with higher concentration of Ti element because the intrinsic hardness of Ti is lower as compared to the intrinsic hardness of Nb and Mo.
The issue of auditory segregation of simultaneous sound sources has been addressed in speech research but was given less attention in musical acoustics. In perception of concurrent speech, or speech with noise, the operation of time-frequency masking was often used as a research tool. In this work, an ex- tension of time-frequency masking, leading to the removal of spectro-temporal overlap between sound sources, was applied to musical instruments playing together. The perception of the original mixture was compared with the perception of the same mixture with all spectral overlap electronically removed. Ex- periments differed in the method of listening (headphones or a loudspeaker), sets of instruments mixed, and populations of participants. The main findings were: (i) in one of the experimental conditions the removal of spectro-temporal overlap was imperceptible, (ii) perception of the effect increased when removal of spectro-temporal overlap was performed in larger time-frequency regions rather than in small ones, (iii) perception of the effect decreased in loudspeaker listening. The results support both the multiple looks hypothesis and the “glimpsing” hypothesis known from speech perception.
In this paper, the effect of changes the parameters of heat treatment on the structure and the degree of elements segregation was
determined, in the context of corrosion resistance of ductile iron Ni-Mn-Cu, containing 7.2% Ni, 2.6% Mn and 2.4% Cu. In the condition
after casting, castings of austenitic matrix and 160HBW hardness were obtained. The achieved castings were soaked at 450, 550 and
650°C for 4, 8 and 12 hours, then cooled down at the ambient air. In most cases, the heat treatment resulted in a change in the castings
matrix, had the consequence of increasing their hardness in comparison to raw castings. Increasing the temperature and prolonging soaking
time resulted in increasing the degree of transformation of austenite, while reducing the degree of elements segregation. This led to the
formation of slightly bigger number of pitting due to corrosion, but not so deep and more evenly distributed in comparison to raw castings.
Wherein the results of corrosion tests show that heat treatment of castings did not significantly change their corrosion resistance in
comparison to raw castings, in contrast to the significant increase in mechanical properties.
Experimental observations of the steel morphology as well as measurements of the solutes concentration in the macro-scale were made on the basis of the vertical cut at the mid-depth of the 15-tons steel forging ingot serially produced in one of the steel plant in Poland. Experimental observations of the morphology accompanied by the measurements of the Peclet Number were also made on the cross-section of the continuously cast brass ingots serially produced in the copper / brass industry in Poland. The performed measurements allowed to work out some maps of the alloying elements segregation for the longitudinal section of the steel static ingot and a Growth Law for the columnar grains formation in the brass ingots. The marginal stability criterion has been applied to the last mentioned development / description. Some suggestions for the micro-segregation measurement mode in the columnar structure are derived.
In the course of homogenizing annealing of aluminium alloys being cast continually or semi-continually it appears that chemical
inhomogenity takes off within separate dendritic cells (crystal segregation). It is about a diffusion process that takes place at the
temperature which approaches the liquid temperature of the material. In that process the transition of soluble intermetallic compounds and
eutectic to solid solution occurs and it suppresses crystal segregation significantly [1]. The temperature, homogenization time, the size of
dendritic cells and diffusion length influences homogenizing process. The article explores the optimization of homogenizing process in
terms of its time and homogenizing annealing temperature which influence mechanical properties of AlZn5,5Mg2,5Cu1,5 alloy.