scholarly journals Chill sensitiveness and thermal analysis parameters relationship in hypo-eutectic, Ca and Ca-La inoculated commercial grey cast irons

2020 ◽  
pp. 20-20 ◽  
Author(s):  
E. Stefan ◽  
M. Chisamera ◽  
I. Riposan
Keyword(s):  
Thin Wall ◽  
Cooling Curves ◽  
Cast Irons ◽  
First Derivative ◽  
Specific Distribution ◽  
Nucleation Sites ◽  
Wedge Shape ◽  
Grey Cast ◽  
Sand Mould ◽  
Thermal Cooling

Previous experiments shown a specific distribution of Al, La and Ca on the section of complex (Mn,X)S compounds, found as major nucleation sites for graphite flakes in low-S cast irons (< 0.03%S), and a possible contribution of La to improve their capacity to nucleate graphite, avoiding carbides formation. In the present work, standard thermal [cooling curves] investigations are undertaken to explore Ca and La-Ca bearing FeSi alloys inoculation effects [10 measurements for each inoculant], in 3.7 - 3.8%CE and optimum S and Mn relationship [0.046 - 0.056%S, (%Mn) x (%S) = 0.024 - 0.029]. Representative temperatures on the cooling curves and under-cooling degrees referring to the meta-stable eutectic temperatures are determined and correlated with the chill [carbides/graphite formation sensitiveness], in different solidification conditions [cooling modulus, wedge shape castings, resin sand mould]. Supplementary addition of La to Ca-bearing inoculants has limited, but specific benefits in these cast irons: lower eutectic recalescence and of the maximum recalescence rate, higher GRF1 and lower GRF2 graphitizing factors and lower value of the first derivative at the end of solidification. Consequently, it results a premise for lower shrinkage sensitiveness and lower chill (carbides) sensitiveness, especially at the highest solidification cooling rate (thin wall castings).

scholarly journals Ce-Bearing FeSi Alloy Inoculation of Electrically Melted, Low Sulphur Grey Cast Irons for Thin Wall Castings

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1122
Author(s):  
Irina Varvara Balkan ◽  
Iulian Riposan
Keyword(s):  
Wall Thickness ◽  
Structural Characteristics ◽  
Cooling Curve ◽  
Thin Wall ◽  
Cast Irons ◽  
Iron Castings ◽  
Grey Cast ◽  
The Difference ◽  
Thermal Cooling ◽  
Fesi Alloy

Electrically melted and over-heated (>1500 °C) grey cast iron at less than 0.04%S, as commonly used, solidifies large amounts of carbides and/or undercooled graphite, especially in thin wall castings; this is necessary to achieve a stronger inoculation. The efficiency of Ce-bearing FeSi alloy is tested for lower ladle addition rates (0.15 and 0.25 wt.%), compared to the base and conventional inoculated iron (Ba,Ca-bearing FeSi alloy). The present work explores chill and associated structures in hypoeutectic grey iron (3.6–3.8%CE, 0.02%S, (%Mn) × (%S) = 0.013–0.016, Alres < 0.002%), in wedge castings W1, W2 and W3 (ASTM A 367, furan resin sand mould), at a lower cooling modulus (1.1–3.5 mm) that is typically used to control the quality of thin wall iron castings. Relatively clear and total chill well correlated with the standard thermal (cooling curve) analysis parameters and structural characteristics in wedge castings, at different wall thickness, displayed as the carbides/graphite ratio and presence of undercooled graphite morphologies. The difference in effects of the two inoculants addition is seen as the ability to decrease the amount of carbides and undercooled graphite, with Ce-bearing FeSi alloy outperforming the conventional inoculant, especially as the wall thickness decreased. It appears that Ce-bearing FeSi alloy could be a solution for low sulphur, electric melt, thin wall iron castings production.

Graphite nucleation sites in commercial grey cast irons

2020 ◽  
Author(s):  
Eduard Stefan ◽  
Mihai Chisamera ◽  
Iulian Riposan ◽  
Stelian Stan
Keyword(s):  
Cast Irons ◽  
Nucleation Sites ◽  
Grey Cast

The Influence of Cooling Rate and Equivalent Carbon on the Chill Tendency and Cooling Curves Parameters in Uninoculated and Inoculated Grey Cast Iron

2016 ◽  
Vol 254 ◽  
pp. 255-260
Author(s):  
Elena Panciu ◽  
Denisa Elena Anca ◽  
Mihai Chisamera
Keyword(s):  
Cast Iron ◽  
Comparative Analysis ◽  
Cooling Rate ◽  
Experimental Research ◽  
Grey Cast Iron ◽  
Carbon Equivalent ◽  
Cooling Curves ◽  
Cast Irons ◽  
Grey Cast ◽  
Equivalent Carbon

The main objectiv of this experimental research is a comparative analysis of the changes caused by varying both of cooling rate and carbon equivalent content on depth of chill tendency and cooling curves parameters of grey cast irons.

scholarly journals Competitive Nucleation in Grey Cast Irons

2017 ◽  
Vol 17 (4) ◽  
pp. 185-189 ◽  
Author(s):  
N. Arab
Keyword(s):  
Chemical Composition ◽  
Cell Density ◽  
Cooling Curve ◽  
Eutectic Solidification ◽  
Image Analyzer ◽  
Eutectic Cell ◽  
Cast Irons ◽  
Nucleation Sites ◽  
Grey Cast ◽  
Eutectic Undercooling

AbstractCast irons are good examples of materials which are more sensitive to chemical composition and production conditions. In this research to improve casting quality, solidification and nucleation process in grey cast iron was investigate. In particular, attempts have been made to rationalize variation in eutectic cells with nucleation sites and eutectic solidification undercooling. Four castings with different diameter and similar chemical composition and pouring temperature and different inoculant percentage was casted. The cooling curve and maximum and minimum undercooling for each castings was measured. Also optical metallography and image analyzer has been used to determine the average eutectic cells diameter, and linear and surface densities, and volume density was calculated. The results of this research show a competitive behavior between nucleation sites and eutectic undercooling. Higher nucleation sites and higher eutectic undercooling cause higher eutectic cell density. But increasing nucleation sites by introducing inoculants to molten metal, is accompanied with reduction in eutectic undercooling. It means that inoculation and undercooling have opposite effect on each other. So, to achieve maximum cell density, it is necessary to create an optimization between these parameters.

Role of Lanthanum in Graphite Nucleation in Grey Cast Iron

2010 ◽  
Vol 457 ◽  
pp. 19-24 ◽  
Author(s):  
Iulian Riposan ◽  
Mihai Chisamera ◽  
Stelian Stan ◽  
Eduard Stefan ◽  
Cathrine Hartung
Keyword(s):  
Flake Graphite ◽  
Nucleation Process ◽  
Cast Irons ◽  
Active Elements ◽  
Nucleation Sites ◽  
Phase Complex ◽  
Grey Cast ◽  
Scanning Electron ◽  
Grey Iron

Specific investigations concerning La-contributions in graphite nucleation process in Ca,Al,La-FeSi inoculated grey cast irons were performed by using a scanning electron microscopy (SEM, EDS). It was re-confirmed that complex (Mn,X)S compounds act as major nucleation sites for graphite flakes. La was mainly concentrated in the first formed oxide-based micro-inclusions (similarly to Al), but also at an important level in the shell of (Mn,X)S compounds (accompanying Ca). It is assumed that La forms micro-inclusions later than Al, as La-reached phase surrounded Al-reached phase. Complex Al-La small micro-inclusions, as possible better nucleation sites for (Mn,X)S compounds and La-Ca presence in the shell/body of these sulphides, possible better nucleation sites for flake graphite, appear to be the peculiar effects of ferrosilicon based inoculants, which include these active elements, promoting type-A graphite, inclusively in low S-grey iron.

scholarly journals Carbide to Graphite Transition Control by Thermal Analysis in Grey Cast Irons

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 993
Author(s):  
Elena Loredana Neacsu ◽  
Iulian Riposan ◽  
Ana Maria Cojocaru ◽  
Stelian Stan ◽  
Iuliana Stan
Keyword(s):  
Thermal Analysis ◽  
Eutectic Reaction ◽  
General Rule ◽  
Thin Wall ◽  
Cast Irons ◽  
Experimental Conditions ◽  
Good Relationship ◽  
Transition Control ◽  
Grey Cast ◽  
Undercooling Degree

The present work compared the solidification pattern of un-inoculated and inoculated hypoeutectic grey cast irons (3.7–3.8% CE), focused on carbide to graphite formation transition, by the use of an adequate experimental technique, able to measure real stable (Tst) and metastable (Tmst) eutectic temperatures. Have been used three ceramic cups for investigating thermal analysis: (i) for normal solidification; (ii) with addition of Te for Tmst measurement; (iii) with more inoculant addition for Tst measurement. As a general rule, measured values appear to be lower compared with calculated values (as chemical composition effects), with an average difference at 14.4 °C for Tst and 8.3 °C for Tmst. It is found a good relationship between the undercooling degree at the lowest eutectic temperature (ΔT1) and at the end of solidification (ΔT3), reported to measured Tmst. The free carbides formation (chill tendency) is in good relationship with the undercooling degree during the eutectic reaction, reported to measured Tmst, especially for thin and medium wall thickness castings. The real measured Tmst instead of calculated Tmst is compulsory for the thin wall castings production, very sensitive to carbides to graphite transition. In the present experimental conditions, no visible relationship appears to be between chill tendency and undercooling at the end of solidification (ΔT3).

Simulation of Thermal Cooling Curves in the Process to Ordering Alloys by the Monte Carlo Method

2021 ◽  
Vol 410 ◽  
pp. 227-234
Author(s):  
Albert R. Khalikov ◽  
Sergey V. Dmitriev
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Stoichiometric Composition ◽  
Square Lattice ◽  
Cooling Curves ◽  
Ordering Kinetics ◽  
The Monte Carlo Method ◽  
Proposed Model ◽  
Coordination Spheres ◽  
Thermal Cooling

An algorithm is proposed for constructing curves of thermal cooling and ordering kinetics with a monotonic decrease in temperature for alloys to stoichiometric composition. Modeling is carried out by the Monte Carlo method in the model of a rigid crystal lattice and pair interatomic interactions. The application of the algorithm is illustrated by the example to a square lattice, taking into account interatomic interactions in the first two coordination spheres for alloys with the composition AB, A3B, and A3B5. The proposed model makes it possible to calculate individual sections of the phase diagrams to the state for binary alloys.

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