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.

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.

Inoculation Enhancing Effects on Chill Tendency in the Mould Inoculated Grey Cast Iron

2015 ◽  
Vol 1128 ◽  
pp. 98-104
Author(s):  
Ion Stefan ◽  
Ciprian Firican
Keyword(s):  
Cast Iron ◽  
Cooling Rate ◽  
Grey Cast Iron ◽  
Carbon Equivalent ◽  
Nucleation Sites ◽  
Grey Cast ◽  
Fesi Alloy ◽  
Grey Iron

Inoculation is a treatment applied to the liquid base iron, to supply one or more elements, such as Al, Ba, Ca, Zr, Sr, Ce, La etc. with active roles in developing graphite nucleation sites. The efficiency of inoculants is directly dependent on the sulphur level: lower sulphur, lower inoculating power or unpredictable results. The objective of this paper is to examine the effects of a S and O containing inoculant enhancer [S,O,Al,Ca-FeSi alloy] to conventional Ca,Ba-FeSi alloy, in the mold treatment of electrically melted grey iron at 0.035%S, 0.002%Al, 0.0005%Zr, (%Mn) x (%S) < 0.02. The wedge test samples [W3 – ASTM A367] were used to evaluate the influence of the cooling rate and inoculation on the carbides formation. It was re-confirmed that for above mentioned critical chemistry conditions, this iron is sensitive to chill formation, despite the carbon equivalent level at 3.8%. Inoculation enhancement increased the effectiveness of the Ca,Ba-FeSi standard inoculant.

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 Researches on the Diffusion Phenomena in the Thermo-Chemical Treatment of Oxy-nitrocarburizing of Some Grey Cast Irons

2019 ◽  
Vol 69 (12) ◽  
pp. 3367-3371 ◽  
Author(s):  
Gina Mihaela Sicoe
Keyword(s):  
Cast Iron ◽  
Chemical Composition ◽  
Chemical Treatment ◽  
White Layer ◽  
Carbon Equivalent ◽  
Chemical Compositions ◽  
Nitrogen Diffusion ◽  
Cast Irons ◽  
Diffusion Phenomena ◽  
Grey Cast

The thermo-chemical treatment of oxy-nitrocarburizing consists in the enrichment of materials in C, N and O in order to improve the physico-mechanical properties and the use of the materials. This leads to the increase in exploitation life, the increase of wear resistance, galling, corrosion, and slight erosion. The research presented in this article followed the study of the application of this treatment and the results obtained on pearlitic grey cast iron with different chemical compositions, domain in which there are few experimental results published. The results obtained on a number of 10 samples, presented in the article, highlighted the good compatibility of these materials with the thermo-chemical treatment of oxy-nitrocarburizing, obtaining on the surface some white layers which give good anti-corrosive properties, similar to those obtained on steel. There was no correlation between the depth of the white layer and the chemical composition of the studied cast iron. It was also emphasized that the depth of nitrogen diffusion is influenced by the chemical composition of the studied materials which is directly proportional to carbon equivalent (Ceq) of cast iron.

scholarly journals ANALISIS MATEMATIS PENGELASAN GREY CAST IRON MENGGUNAKAN PROSES GTAW DENGAN DAN TANPA PREHEAT

2021 ◽  
Vol 9 (1) ◽  
pp. 14-21
Author(s):  
Doty Dewi Risanti
Keyword(s):  
Cast Iron ◽  
Steady State ◽  
Arc Welding ◽  
Travel Speed ◽  
Grey Cast Iron ◽  
Carbon Equivalent ◽  
Quasi Steady State ◽  
White Iron ◽  
Gas Tungsten Arc ◽  
Grey Cast

Pemberian pemanasan awal pada proses pengelasan memberikan efek pengurangan tegangan, distorsi, retakan dan kekerasan pada daerah Heat Affected Zone (HAZ) dengan memperlambat laju pendinginan. Distribusi temperatur saat pengelasan didekati dengan menggunakan persamaan analitik Rosenthal pada logam grey cast iron. Grey cast iron termasuk sulit untuk dilas dan memerlukan perlakuan khusus. Pada penelitian ini, perhitungan distribusi temperatur dan laju pendinginan dibandingkan dengan struktur mikro dan kekerasan untuk grey cast iron yang dilas dengan menggunakan Gas Tungsten Arc Welding (GTAW). Persamaan Rosenthal dengan solusi Bessel hanya cocok untuk distribusi temperatur pada daerah lelehan, sedangkan solusi quasi steady state dapat digunakan untuk prediksi distribusi temperatur arah lateral dan transversal pada logam lasan. Preheating pada suhu 315  berpengaruh pada lebar HAZ yang dihasilkan menurut persamaan eksponensial terhadap travel speed, memperlambat laju pendinginan dan menurunkan kekerasan karena berkurangnya carbon equivalent (CE). Struktur mikro HAZ pada grey cast iron yang diberi preheating menunjukkan dominasi martensit nikel dan eutektik ledeburit, sedangkan tanpa preheating menghasilkan struktur mikro didominasi oleh eutektik ledeburit dan besi karbida dalam white iron.

The Influence of the Cooler Material on the Structure and Hardeness Gradient of a Grey Pearlitic Cast Iron

2015 ◽  
Vol 1128 ◽  
pp. 18-25 ◽  
Author(s):  
Sorin Ion Munteanu ◽  
Ioan Ciobanu ◽  
Aurel Crisan ◽  
Tibor Bedo ◽  
Daniel Feraru
Keyword(s):  
Cast Iron ◽  
Cooling Rate ◽  
Hardened Layer ◽  
Superficial Layer ◽  
Physical Characteristics ◽  
Grey Cast Iron ◽  
Industrial Practice ◽  
Iron Castings ◽  
Iron Sample ◽  
Grey Cast

The structure and properties of grey cast iron castings are considerably influenced by the cooling rate during solidification. In order to obtain grey cast iron parts with a hard superficial layer (wear resistant), external metallic coolers are placed on those surfaces during casting. This is the case of cam pushers, camshafts, driving shafts, metalworking rolls, etc. Cast iron coolers or steel coolers are mostly used in practice. The cooling rate during solidification is influenced by the thermo-physical characteristics of the coolers. This paper presents the results obtained by simulation and experimental research on coolers material influence on the structure and hardness of the surface layer of a pearlitic cast iron sample. It was studied the solidification of samples with dimensions 20 x 20 x 60 mm, cast of pearlitic cast iron in six variants: without a cooler and in the presence of some metallic coolers of different thermo-physical characteristics (iron, steel, copper, titanium and aluminum coated with a thin layer of steel). It was studied the influence of cooler material on structure of the superficial layer, on thickness of the hardened layer, on superficial hardness, on the temperature field and cooling rates. Conclusions are drawn regarding these influences and the possibility of using external coolers in industrial practice.

Effect of Cooling Rate on Drop-Tube Processed Commercial Grey Cast Iron

2015 ◽  
Author(s):  
Olamilekan R. Oloyede ◽  
Tim Bigg ◽  
Andrew M. Mullis
Keyword(s):  
Cast Iron ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Microstructural Analysis ◽  
Control Sample ◽  
Grey Cast Iron ◽  
Drop Tube ◽  
Flake Graphite ◽  
Cooling Rates ◽  
Grey Cast

This study focuses on the fundamental of solidification of commercial grey cast iron as a function of the externally applied cooling rate. Grey cast iron powders were prepared using the drop-tube method, which is a good analogue for commercial production via high pressure gas atomization. The as-solidified droplets were collected and sieved into size ranges from > 850 μm to < 53 μm diameter, with estimated cooling rates of 500 K s−1 to 75,000 K s−1, with each sieve fraction being prepared for metallographic characterization. The microstructure and phase composition of the powders were analyzed using XRD, optical and scanning electron microscopy, with the results being compared against a control sample subject to slow cooling in the drop-tube crucible; which has typical grey cast iron microstructure with extensive flake graphite in a largely ferrite matrix. In contrast, flake graphite was absent in virtually all the drop-tube samples, even in those with the most modest cooling rates. Microstructural analysis revealed that as the cooling rate increased there was less fragmentation of the primary austenite/ferrite dendrites and the volume fraction of primary dendritic material increased. Hence, as the particle fractions get smaller (D < 106 μm) there is a distinct microstructural evidence of a martensite phase which is related to its better mechanical properties (microhardness) as the sample sizes decrease.

Microstructure and Properties of High Carbon Equivalent Gray Cast Iron Modified by Rare Earth

2011 ◽  
Vol 295-297 ◽  
pp. 962-968
Author(s):  
Fu Min Chu ◽  
Xin Hui Zu ◽  
Zhong Kui Zhao ◽  
Xiao Yun Jiang
Keyword(s):  
Rare Earth ◽  
Cast Iron ◽  
Rare Earth Metal ◽  
Gray Cast Iron ◽  
Earth Metal ◽  
Gray Cast ◽  
Carbon Equivalent ◽  
High Carbon ◽  
Microstructure And Properties ◽  
The Rare Earth

Microstructure and properties of the high carbon equivalent gray cast iron modified by the rare earth metal are investigated by optical microscopy, scanning electronic microscopy, Brinell hardness and tensile testing. The results show that the primary austenite dendritic is refined, and the morphology of graphite is transformed from A-type to D-type undercooling graphite with increment of the rare earth metal (REM), even with the vermicular graphite present. The lamellae are becoming thinner with increment of rare earth metal. There are double peaks between the addition of the rare earth metal and the tensile strength/hardness. The iron would have the best comprehensive property when 0.30% REM is added.

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