Revisiting the graphite nodule in ductile iron

2019 ◽  
Vol 161 ◽  
pp. 66-69 ◽  
Author(s):  
Ehsan Ghassemali ◽  
Juan Carlos Hernando ◽  
Doru M. Stefanescu ◽  
Attila Dioszegi ◽  
Anders E.W. Jarfors ◽  
...  
Keyword(s):  
Ductile Iron ◽  
Graphite Nodule

scholarly journals The Role of Microstructure on Tensile Plastic Behavior of Ductile Iron GJS 400 Produced through Different Cooling Rates, Part I: Microstructure

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1282 ◽  
Author(s):  
Giuliano Angella ◽  
Dario Ripamonti ◽  
Marcin Górny ◽  
Stefano Masaggia ◽  
Franco Zanardi
Keyword(s):  
Grain Size ◽  
Tensile Properties ◽  
Ductile Iron ◽  
Microstructural Characterization ◽  
Graphite Nodule ◽  
Plastic Behavior ◽  
Quantitative Metallography ◽  
Cooling Rates ◽  
X Ray

A series of samples made of ductile iron GJS 400 was cast with different cooling rates, and their microstructural features were investigated. Quantitative metallography analyses compliant with ASTM E2567-16a and ASTM E112-13 standards were performed in order to describe graphite nodules and ferritic grains. The occurrence of pearlite was associated to segregations described through Energy Dispersive X-ray Spectroscopy (EDS) analyses. Results were related to cooling rates, which were simulated through MAGMASOFT software. This microstructural characterization, which provides the basis for the description and modeling of the tensile properties of GJS 400 alloy, subject of a second part of this investigation, highlights that higher cooling rates refines microstructural features, such as graphite nodule count and average ferritic grain size.

Effect of Mould Runner and Coating on Graphite Nodule Characteristics and Hardness of Thin Wall Ductile Iron

2011 ◽  
Vol 264-265 ◽  
pp. 266-271 ◽  
Author(s):  
Hassan Jafari ◽  
Mohd Hasbullah Idris ◽  
Ali Ourdjini ◽  
Hamid Reza Bakhsheshi Rad ◽  
Seyed Sadegh Khayat Ardestani ◽  
...  
Keyword(s):  
Molten Metal ◽  
Ductile Iron ◽  
Hardness Test ◽  
Optical Microscope ◽  
Graphite Nodule ◽  
Carbon Equivalent ◽  
Image Analyzer ◽  
Thin Wall ◽  
Save Energy ◽  
Hardness Values

Due to its attractive characteristics, thin wall ductile iron (TWDI), has been increasingly considered as a preference for reducing material consumption in order to save energy and contribute less environment pollutions as well as decreasing costs. In this research, the effect of two mould runner gating systems and mould coating on graphite nodule characteristics and hardness values of TWDI casting was studied. Strip samples with various thicknesses of 2.3, 3.3, 4.5, 5.4, 6.5, 7.5 and 8.5 mm were casted into CO2 Silicate moulds designed by two gating systems namely stepped and tapered runners. Half of the moulds were coated by graphite-based zircon material to investigate the effect of mould coating on the graphite nodule qualities and quantities. The molten metal prepared contained carbon equivalent (CE) of 4.29% and was poured at the temperatures of 1450°C. Optical microscope (OM) and Clemex Image Analyzer (CIA) were used to evaluate graphite nodule count, roundness and diameter of the nodules of the TWDI cast samples. Brinell hardness test was performed on all samples. The results show that roundness and graphite nodule counts in the microstructure of the samples produced in stepped runner gating system and uncoated mould decrease whereas graphite nodules diameter shows opposite behaviour. Furthermore, molten metal experienced a superior fluidity in coated moulds. Moreover, the TWDI samples achieved a significant improvement in the value of hardness.

Effect of Yttrium-Containing Nodulizer on the Microstructure Formation and Mechanical Properties of Heavy Section Ductile Iron Castings

2010 ◽  
Vol 457 ◽  
pp. 73-78 ◽  
Author(s):  
Qin Xin Ren ◽  
Ming You ◽  
Yun Bang Yao ◽  
Guang Min Wen ◽  
Qi Zhou Cai
Keyword(s):  
Mechanical Properties ◽  
Ductile Iron ◽  
Graphite Nodule ◽  
High Melting ◽  
Microstructure Formation ◽  
High Melting Point ◽  
Iron Castings ◽  
Heavy Section ◽  
Long Time ◽  
Pearlite Content

Ductile iron specimens with dimensions of 400mm×400mm ×450mm were prepared by treating the melt with an yttrium-containing nodulizer. The effect of yttrium on microstructure and mechanical properties was investigated, and the formation of degenerate graphite was discussed as well. The results show that the yttrium-containing nodulizer has good nodulization fading resistance for heavy section ductile iron, since the high melting point hexagonal oxide Y2O3 particles were formed from the nodulizer in the melt and those could act as heterogeneous nuclei for graphite nodule for a long time. Segregation of Ti and MgO at grain boundaries broke the austenite shell, resulting in graphite degeneration. When heavy section ductile iron castings with pearlite matrix were cast, graphite nodule size became finer and the nodularity of graphite nodules improved due to the addition of 0.01wt% Sb to the melt, and pearlite content in specimens increased due to alloying with Cu, Cr, Mo. The heavy section ductile iron tool bed was fabricated by treating the melt with the yttrium-containing nodulizer and Ni. The nodularity of the attached block was 85%~90%, tensile strength, elongation and impact toughness were 440MPa, 23.3% and 5.0J/cm2 respectively.

Microstructure and XRD of Ductile Iron Using Annealing-Tempering Heat Treatment Process

2013 ◽  
Vol 393 ◽  
pp. 83-87
Author(s):  
Mohd Faizul Idham ◽  
B. Abdullah ◽  
Junaidi Syarif ◽  
Ahmed Jaffar ◽  
Siti Khadijah Alias ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Ductile Iron ◽  
Xrd Analysis ◽  
Graphite Nodule ◽  
Tempering Temperature ◽  
Treatment Processes ◽  
Heat Treated ◽  
Different Temperatures ◽  
Metallographic Observation ◽  
Graphite Structure

In this present study, the effect of tempering temperature of annealing-tempering combination processes, on microstructure as well as exploring the phase constituents of ductile iron through XRD analysis were performed. Ductile iron produced through conventional CO2sand casting method was performed annealing-tempering heat treatment processes by using change furnace method. Three different temperatures were investigated ranging from (i) 250 °C, (ii) 300 °C and (iii) 350 °C for 1.5 hours respectively. Standard metallographic observation and XRD analysis were done to characterize the microstructure and the constituents respectively. It is found that the graphite structure exist in both treated and untreated samples. Pearlitic structure was formed in the microstructure for heat treated samples. Ferritic-pearlitic matrix structure surrounding the graphite nodule has been shown in as-cast sample. Annealing-tempering process does not change the BCC ferrite peak in (200), (211), (220) and (310) planes shown in as-cast.

scholarly journals Influence of Cooling Rate on Microstructure Formation of Si–Mo Ductile Iron Castings

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1634
Author(s):  
Marcin Górny ◽  
Magdalena Kawalec ◽  
Beata Gracz ◽  
Mirosław Tupaj
Keyword(s):  
Cooling Rate ◽  
Ductile Iron ◽  
Metallic Matrix ◽  
Graphite Nodule ◽  
Microstructure Formation ◽  
Cooling Rates ◽  
Iron Castings ◽  
Cooling Conditions ◽  
Wide Range ◽  
Longitudinal Ultrasonic Wave

The present study highlights the effect of the cooling rate on the microstructure formation of Si–Mo ductile iron. In this study, experiments were carried out for castings with different wall thicknesses (i.e., 3, 5, 13, and 25 mm) to achieve various cooling rates. The simulation of the cooling and solidification was performed through MAGMASOFT to correlate the cooling conditions with the microstructure. The phase diagram of the investigated alloy was calculated using Thermo-Calc, whereas the quantitative metallography analyses using scanning electron microscopy and optical microscopy were performed to describe the graphite nodules and metallic matrix morphologies. The present study provides insights into the effect of the cooling rate on the graphite nodule count, nodularity, and volumetric fractions of graphite and ferrite as well as the average ferritic grain size of thin-walled and reference Si–Mo ductile iron castings. The study shows that the cooling rates of castings vary within a wide range (27 °C–1.5 °C/s) when considering wall thicknesses of 3 to 25 mm. The results also suggest that the occurrence of pearlite and carbides are related to segregations during solidification rather than to cooling rates at the eutectoid temperature. Finally, the present study shows that the longitudinal ultrasonic wave velocity is in linear dependence with the number of graphite nodules of EN-GJS-SiMo45-6 ductile iron.

EFFECT OF Ce ON GRAPHITE NODULE COUNT AND SIZE DISTRIBUTION IN DUCTILE IRON

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1853-1860 ◽  
Author(s):  
XIAOGANG DIAO ◽  
ZHILIANG NING ◽  
FUYANG CAO ◽  
JIANFEI SUN
Keyword(s):  
Size Distribution ◽  
Ductile Iron ◽  
Graphite Nodule ◽  
Spheroidal Graphite ◽  
Nodule Count ◽  
Edx Analysis ◽  
Spherical Graphite ◽  
Mean Diameter ◽  
Addition Level

The graphite nodule density and size distribution are two very important parameters in the characterization of the microstructures of ductile iron. Various amount of cerium element ( Ce ) (from 0.005% to 0.020%) were added into ductile iron cast in sand moulds to investigate the effect of Ce concentration on graphite nodule count and size distribution. The addition of Ce has a significant effect on solidified microstructures of ductile iron. Increasing of Ce concentration from 0.005% to 0.014%, an obvious increase in nodule graphite amount is achieved and graphite size becomes finer. When the addition level of Ce reaches 0.018% or 0.020%, spheroidal graphite begins to coarsen, resulting in the decrease in graphite amount and formation of the some non-spherical graphite. An evident nucleus and faceted crystals inside a nodule are clearly distinguished and the thin flakes that constitute the nodule are observed from the SEM photograph. EDX-analysis of nucleus of the spheroidal graphite shows that it is composed of sulfur, cerium, magnesium and trace calcium. The 3-D nodule count of ductile iron is 11.7 × 103/ mm 3 with 0.005% Ce addition. The value is 45.8 × 103/ mm 3 with Ce addition up to 0.014% and the majority of diameter is less than 30 µm. However, with 0.018% Ce residual, the nodule count decreases to 29.0 × 103/ mm 3. The value is close to that of 0.018% Ce when Ce concentration is 0.020%, and the majority of diameter is less than 40 µm. The results indicate that the graphite nodule count reaches the maximum and mean diameter reaches the minimum with 0.014% Ce residual existing in ductile iron.

Influence of casting size and graphite nodule refinement on fracture toughness of austempered ductile iron

1998 ◽  
Vol 29 (10) ◽  
pp. 2511-2521 ◽  
Author(s):  
Shen-Chih Lee ◽  
Cheng-Hsun Hsu ◽  
Hui-Ping Feng ◽  
Chao-Chia Chang
Keyword(s):  
Fracture Toughness ◽  
Ductile Iron ◽  
Austempered Ductile Iron ◽  
Graphite Nodule

Numerical Analysis of the Influence of Graphite Nodule Size on the Pitting Resistance of Austepered Ductile Iron Gears

2015 ◽  
Vol 1120-1121 ◽  
pp. 763-772 ◽  
Author(s):  
Luiz Henrique Accorsi Gans ◽  
Wilson Luiz Guesser ◽  
Marco Antonio Luersen ◽  
Carlos Henrique da Silva
Keyword(s):  
Wear Resistance ◽  
Ductile Iron ◽  
Maximum Shear Stress ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Graphite Nodule ◽  
Element Analysis ◽  
Aisi 4140 Steel ◽  
Nodule Size ◽  
Aisi 4140

In this work, an experimental study of wear evaluation in combination with a finite element analysis (FEA) was carried out for austempered ductile iron (ADI) used in gears. Two different ADI materials were used to produce gears which were tested in a FZG back-to-back test rig. The experimental results were compared to those of carburized AISI 8620 steel and induction hardened AISI 4140 steel gears. The wear resistance for pitting and spalling on the gears surfaces were measured using image analysis. Comparing the two types of ADI, the one with smaller nodules showed a higher pitting resistance. In contact fatigue tests with severe load, the carburized AISI 8620 steel proved to be superior to ADI. However, ADI with smaller nodule size presented wear resistance similar to that of induction hardened AISI 4140 steel. The FEA was conducted using the commercial code ANSYS 11.0 and aimed to provide a better understanding of the microstructural effect on the stress state of subsurface regions. From the numerical results in ADIs, it was concluded that the nodule size affects the gears life independently of the mechanical properties of the matrix. The size and number of nodules affects both the nucleation and the propagation stages of cracks. ADIs with higher amount of nodules have a superior wear resistance by pitting. Also, compared to the Hertz contact theory (valid for isotropic materials), the presence of graphite nodules induced the maximum shear stress point moves toward the surface.

Using Cored Wire Injection Method in the Production of Austenitic High Ni-Alloyed Ductile Iron Castings

2013 ◽  
Vol 58 (3) ◽  
pp. 969-972 ◽  
Author(s):  
E. Guzik ◽  
D. Wierzchowski
Keyword(s):  
Ductile Iron ◽  
Raw Materials ◽  
Nodular Cast Iron ◽  
Treatment Method ◽  
Magnesium Content ◽  
Graphite Nodule ◽  
Cored Wire ◽  
Injection Method ◽  
Iron Castings ◽  
Coreless Induction Furnace

Abstract Below are described results of the analysis concerning the use of two cored wire injection method (2PE- 9) and the unique application of a drum ladle as a treatment, transport and casting one, instead of a vertical treatment ladle. Parameter optimization, like: length of nodulariser wire, residual magnesium content, treatment and pouring temperature have been shown. Influence of various treatment temperatures, magnesium-cored wire velocities (Mg-treatment times) and weights of molten alloy on magnesium recovery are demonstrated. Moreover, graphite nodule content in relation to different raw materials in the charge mix are presented. Typical microstructure, mechanical properties and treatment costs are given as well. Using specific industrial conditions for tests and optimal, low scrap production of austenitic nodular cast iron (EN-GJSA-XNiSiCr35-5-2 Grade, according with EN 13835), makes this innovative method very credible. Injection of two Ø 9 mm wires; cored in FeSi + Mg nodulariser mixture and inoculant master alloy into a drum ladle is a treatment method that can be used for the production of ductile iron melted in a coreless induction furnace.

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