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.

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).

Structure Characteristics of Ce-Inoculated, Low Sulphur Grey Cast Irons

2012 ◽  
Vol 188 ◽  
pp. 318-323 ◽  
Author(s):  
Irina Anton ◽  
Iulian Riposan
Keyword(s):  
Control Parameter ◽  
Structural Characteristics ◽  
Sulphur Content ◽  
Structure Parameters ◽  
Cast Irons ◽  
Structure Characteristics ◽  
Grey Cast ◽  
Fesi Alloy

The structural characteristics of electric melt, as-cast grey irons were studied in critical solidification conditions, such as very low sulphur content (< 0.025%) and a low (%Mn) x (%S) control parameter (< 0.015) with low Al residual (< 0.002%), without resulphurising or preconditioning. The efficiency of Ce-Ca-Al-FeSi alloy was tested at lower addition rates (0.15-0.25wt.%), as traditionally high inoculant addition rates have been employed in low sulphur grey cast irons. Ce bearing ferrosilicon with similar Ca and Al levels appears to be more efficient than a commercial Ba-Ca-Al-FeSi inoculant, especially at low addition rates (< 0.2wt.%) for the key structure parameters: fewer carbides and less undercooled graphite with small eutectic cells at a higher count.

Inoculating Influence of Re-Carburizers in Grey Cast Iron

2007 ◽  
Vol 23 ◽  
pp. 287-290
Author(s):  
Iulian Riposan ◽  
Mihai Chisamera ◽  
Stelian Stan ◽  
P. Toboc
Keyword(s):  
Cast Iron ◽  
Carbon Materials ◽  
Analysis Data ◽  
Grey Cast Iron ◽  
Cast Irons ◽  
Graphite Morphology ◽  
Grey Cast ◽  
The Difference ◽  
Solidification Parameters ◽  
Potential Carbon

In laboratory experiments Thermal Analysis data were recorded and different solidification parameters were identified to characterize the inoculation effect of the carbon materials (amorphous and crystalline structure) in low sulphur (<0.025 %S) grey cast iron. These parameters are linked to graphite morphology as well as chill formation in carburized cast irons. In low sulphur base iron the difference in inoculation efficiency between crystalline and amorphous carbon materials is limited. Secondary granular carbon materials, previously used as conductive or resistive media in electric graphitizing furnaces were found to be potential carbon raisers with visible inoculation effects in grey irons, especially those from a petroleum coke origin. A controlled presence of a low amount of SiC (2-3%) is effective, including low sulphur grey 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.

Influence of Cooling Rate on the Structural Characteristics of Ca and Rare Earth Inoculated, Low-S Grey Cast Iron

2014 ◽  
Vol 216 ◽  
pp. 73-78
Author(s):  
Lavinia Marilena Harcea ◽  
Iulian Riposan
Keyword(s):  
Rare Earth ◽  
Cast Iron ◽  
Cooling Rate ◽  
Structural Characteristics ◽  
Critical Conditions ◽  
Carbon Equivalent ◽  
Thin Wall ◽  
Effective Solution ◽  
End Effect ◽  
Grey Cast

The structural characteristics of low S (0.025%), low Al (<0.003%) and 4.0% carbon equivalent (CE) electric melted grey irons were studied at different solidification rates, for Ca and Ca,RE [Mischmeta as the inoculating elements. Despite a relatively high CE, this base iron is sensitive to undercooling during solidification. A conventional Ca-FeSi inoculant is not recommended for these critical conditions, especially to avoid undercooled graphite morphologies. It is only adequate to control free carbides, for castings with more than 15mm section. Rare earth (RE) bearing CaFeSi alloy appears to be a more effective solution, at least for castings with more than 5mm section to control carbides, even the end effect, and promote a homogeneous structure. Undercooled graphite presence was limited and avoided in more than 10mm section. Thin wall castings, less than 5mm section, requiring stronger control for carbides and undercooled graphite formation, should not be produced from this type of base iron, unless more efficient inoculation can be accomplished.

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).

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