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 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.

scholarly journals Effect of the Cooling Rate on the Graphite Nodule Count and Size Distribution in Nodular Cast Iron

2018 ◽  
Vol 925 ◽  
pp. 45-53
Author(s):  
Haji Muhammad Muhmond ◽  
Hasse Fredriksson
Keyword(s):  
Cooling Rate ◽  
Size Distribution ◽  
Great Influence ◽  
Nodular Cast Iron ◽  
Graphite Nodule ◽  
Cooling Rates ◽  
Nodule Count ◽  
Cooling Conditions ◽  
Different Temperatures ◽  
Two Parameters

The graphite nodule count, size distribution and homogenization of the nodules distribution are the factor which are of more significance for the properties of the material. By just increasing the inoculants or Mg will not help to get rid of problems like the un-even size distribution and or increasing the nodule count. The cooling conditions of the melt prior to solidification and during solidification can control these two parameters to a large extent. In this research, it is more emphasized on the nucleation sequence of MgO particles and on the cooling rates. The nucleation of MgO at different temperatures and at different cooling rates was found to have a great influence on the nodule size distribution and the homogenization of the microstructure. A mathematical model was derived to relate the Mg concentration in the liquid to the cooling rate, prior to solidification. The MgO particles count was calculated as a function of cooling rate. It was found that at higher cooling rates, MgO can be nucleated in multi steps during cooling process, which can increase the nodule count tremendously.

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.

scholarly journals Using Cored Wires Injection 2PE-9 Method in the Production of Ferritic Si-Mo Ductile Iron Castings

2012 ◽  
Vol 12 (4) ◽  
pp. 53-56
Author(s):  
E. Guzik ◽  
D. Wierzchowski
Keyword(s):  
Ductile Iron ◽  
Metallic Matrix ◽  
Nodular Cast Iron ◽  
Treatment Method ◽  
Mean Values ◽  
Iron Castings ◽  
Casting Ladle ◽  
Coreless Induction Furnace ◽  
Nodular Graphite ◽  
Cored Wires

Abstract The results of studies on the use of modern two cored wires injection method for production of ferritic nodular cast iron (ductile iron) with use of unique implementation of drum ladle as a treatment / transport and casting ladle instead vertical treatment ladle was described. The injection of length of Ø 9mm wires, cored: in FeSi + Mg nodulariser mixture and inoculant master alloy is a treatment method which can be used to produce iron melted in coreless induction furnace. This paper describes the results and analysis of using this method for optimal production of ductile iron under specific industrial conditions. It means, that length of nodulariser wire plus treatment and pouring temperatures were optimized. In this case, was taken ductile iron with material designation: EN-GJS-SiMo40-6 Grade according EN 16124:2010 E. Microstructure of great number of trials was controlled on internally used sample which has been correlated with standard sample before. The paper presents typical ferritic metallic matrix and nodular graphite. Additionally, mechanical properties were checked in some experiments. Mean values of magnesium recovery and cost of this new method from optimized process parameters were calculated as well.

Microstructure Evolution of Heavy Section Ductile Iron

2010 ◽  
Vol 97-101 ◽  
pp. 1020-1023 ◽  
Author(s):  
Xiao Gang Diao ◽  
Zhi Liang Ning ◽  
Fu Yang Cao ◽  
Shan Zhi Ren ◽  
Jian Fei Sun
Keyword(s):  
Cooling Rate ◽  
Ductile Iron ◽  
Solidification Time ◽  
Cooling Curve ◽  
Eutectic Solidification ◽  
Spheroidal Graphite ◽  
Eutectic Cell ◽  
Cooling Curves ◽  
Iron Castings ◽  
Heavy Section

Ductile iron, Heavy section, Cooling curve, Microstructure, Cooling rate. Abstract. Two 250×250×250 mm cubic ductile iron castings solidified in sand and insulation mould were fabricated. The effect of cooling rate on graphite and matrix microstructure of heavy section ductile iron together with their cooling curves were evaluated. Results show that increasing the cooling rate leads to fine graphitization and favors spheroidal graphite formation. The matrix structure is fully ferrite structure at the edge of both castings, while pearlite can be seen near the eutectic cell boundaries at the center of two castings. Furthermore, the amount of pearlite increases with increasing solidification time. Cooling curves confirm that cooling rate affects solidification time of the eutectic transformation and characteristic temperature points on the cooling curves remain unchanged. Low cooling rate appears to significantly increase the eutectic plateau length. Besides, cooling curves show that eutectic temperature remains constant (about 1160°C), which allows for spheroidal graphite formation. Undercooling and inoculation fading during the long time eutectic solidification lead to pearlite formation in the center of cubic ductile iron castings.

scholarly journals Welding thermal stress diagrams as a means of assessing material proneness to residual stresses

2020 ◽  
Vol 56 (2) ◽  
pp. 1694-1712
Author(s):  
Andrii Mishchenko ◽  
Américo Scotti
Keyword(s):  
Thermal Stress ◽  
Cooling Rate ◽  
Thermal Stresses ◽  
Physical Simulation ◽  
Deformation Behaviour ◽  
Stress Generation ◽  
Cooling Rates ◽  
Wide Range ◽  
Quantitative Manner ◽  
Critical Regions

Abstract In this work, the proposal and appraisal of a method to describe in a quantitative manner the phenomenon of thermal stresses formation in welding at different heat-affected zone (HAZ) regions and under different cooling rates, by means of physical simulation, are explained. Under the denomination of welding thermal stress diagrams (WTSD), initially the concept and experimental arrangements needed to use the idea, based on a Gleeble simulator, are revealed. An approach to determine more realistic thermal cycles (peak temperature and heating/cooling rates) is introduced and applied. The method assessment was carried out by using specimens of a HSLA quenchable steel subjected to different cooling rates (covering a wide range of typical welding heat inputs) and peak temperatures (representing regions progressively farther away from the fusion line). The different thermal stress (TS) curves proved the concept based on the justification of the results. In addition, it was physically demonstrated that TS curves are governed mainly by two complex concurrent phenomena, namely contraction under restriction of heated areas and the expansibility of phase transformation. It was concluded that due to this balance, the highest residual stress (RS) does not occur either at slowest cooling rate or at fastest cooling rate. Nevertheless, the highest RS may not occur at the coarse grain zone either. TS progressively drops along the HAZ regions away from critical regions, and even at sub-critical regions there is tensile RS. Complementarily, it was also concluded that WTSD by physical simulation allows one to determine the deformation behaviour of a material as a function of temperature. This information can be used as input or calibration in modelling for thermal stress generation in steels.

Crystallization Behaviour of Polytetrafluoroethylene over very Large Cooling Rate Domains

2013 ◽  
Vol 747 ◽  
pp. 201-204
Author(s):  
Nicolas Bosq ◽  
Nathanaël Guigo ◽  
Nicolas Sbirrazzuoli
Keyword(s):  
Cooling Rate ◽  
Glassy State ◽  
Crystalline Polymer ◽  
Sem Analysis ◽  
Scanning Calorimetry ◽  
Theoretical Dependence ◽  
Cooling Rates ◽  
Fast Scanning Calorimetry ◽  
Wide Range ◽  
Fast Cooling

Polytetrafluoroethylene (PTFE) is a semi-crystalline polymer that demonstrates a very fast crystallization process on cooling. This study investigates the nonisothermal PTFE ultra-fast crystallization over a wide range of cooling rates via conventional Differential Scanning Calorimetry (DSC), Fast Scanning Calorimetry (FSC) and Ultra-Fast Scanning Calorimetry (UFSC). A new knowledge about crystallization kinetics of PTFE is obtained from the data obtained under very fast cooling rates. The shift of the melting peak to lower temperature shows that the crystals formed under fast cooling rates are slightly less stable than those produced under slower cooling rates. SEM analysis allows to observe these differences in crystal morphologies. According to the results, the crystallization is still present even for the fastest cooling rate employed and in consequences it is impossible to reach a metastable glassy state. The effective activation energy (Eα) displays a variation with the relative extent of crystallization (α) that is characteristic of a transition of PTFE crystallization from regime II to regime III around 312°C. Following the Hoffman-Lauritzen theory the Eα dependency obtained from the crystallizations under the different cooling rates was fitted in order to study the theoretical dependence of the growth rate.

Sign in / Sign up

Export Citation Format

Share Document