Papers by Keyword: Nodular Cast Iron

Abstract: This study investigated the evolution of microstructure, hardness, and toughness in nodular cast iron following quenching and tempering at 450°C. The research explored how the heat treatment process impacts these mechanical properties, to identify an optimal balance between hardness and toughness. Untreated nodular cast iron displayed a microstructure comprising ferrite, pearlite, and spheroidal graphite, resulting in moderate hardness (24.33 HRC) and toughness (0.082 J/mm²). Quenching at 850°C, followed by rapid cooling in water, induced the formation of martensite, a hard and brittle phase, which significantly increased hardness to 56.73 HRC but decreased toughness to 0.068 J/mm². Tempering at 450°C transformed the martensite into tempered martensite, reducing hardness to 41.37 HRC while improving toughness to 0.11 J/mm². These findings highlighted the importance of tempering in achieving a better balance between hardness and toughness, making the material suitable for industrial applications requiring both wear resistance and impact durability. The results offered valuable insights for optimizing heat treatment procedures to enhance the performance and durability of nodular cast iron components in various industries.

Abstract: Welding plays an important role in the component joining process. This study aimed to determine the effect of shielded metal arc welding on the microstructure, hardness and tensile strength of nodular cast iron. Shielded metal arc welding was performed using AWS A5.15 Eni-CL electrodes. Scanning Electron Microscope is used for metallographic observation. Hardness testing was carried out on base metal, heat-affected zone, and weld metal. This hardness test uses the Vickers technique. Tensile testing was carried out to determine the effect of welding on tensile strength. The results of the metallographic investigation showed the disappearance of the ferrite phase and the appearance of the ledeburite phase in the heat-affected zone and weld metal. The area with the highest hardness occurs in the heat-affected zone while the lowest hardness occurs in the weld metal. There is a decrease in the tensile strength of nodular cast iron due to the welding process.

Abstract: Gray cast iron has graphite flakes which makes it relatively weak and brittle. The addition of magnesium to gray cast iron resulted in nodular cast iron which has spherical graphite. The aim of this research was to investigate the changes in the microstructure and strength due to the addition of magnesium to gray cast iron. Microstructure observations were made by metallographic testing using Scanning Electron Microscopy and Energy Dispersive Spectroscopy. Tensile testing was carried out to measure the yield strength, tensile strength, and modulus of elasticity. The addition of magnesium to gray cast iron was observed to increase the yield strength by 179%, tensile strength by 238%, and decrease the modulus of elasticity by 94%.

Abstract: Nodular cast iron is usually used for components that require good mechanical properties such as strength, toughness, and ductility. Heat treatment is applied to the components made from the nodular cast iron to improve their mechanical properties. This study aimed to investigate the influence of tempering time on the microstructure, hardness, and wear rate of nodular cast iron. The heat treatment was performed by austenitizing to 850 °C with a holding time of 1 hour and quenched in the oil medium. After quenching, it was tempered at a temperature of 450 °C by varying the tempering time to 15, 30, 45, and 60 min. The investigation consists of microstructure observation, hardness, and wear rate measurements. The results show that the highest hardness was 55.3 HRC at a tempering time of 15 min, and the lowest hardness was 54 HRC at a tempering time of 60 min. The lowest wear rate was 0.00476 g/min at a tempering time of 15 min, and the highest wear rate was 0.00574 g/min at a tempering time of 60 min. It can be concluded that the longer the holding time of tempering, the lower the hardness and the higher the wear rate.

Abstract: The microstructure and mechanical properties of the work roll grade acicular nodular cast iron supplied by two different manufacturers were studied and compared. These rolls have different chemical compositions, namely work roll A and work roll B, respectively. This work aims to evaluate the two different work rolls with different chemistry and the effect on the microstructure and hardness. The microstructure was observed by the optical microscope and image analyzer, and the hardness value was measured using a Rockwell hardness machine. The results showed that the work roll A presented more carbides and graphite nodules than B. Carbide area fraction and nodularity level of work roll A are found much higher than B; therefore, it provided a higher hardness. It seems a higher percentage of carbon and proper amount of magnesium as a nodulizer contributed to produce more carbides and nodules on the cast iron of work roll A compared to B.

Abstract: In this study, an attempt has been made to produce ductile iron or spheroidal graphite iron and to study its important properties with a view to reduce the import of machinery parts made of ductile iron. Locally available compressor scrap (i.e. the compressor cylinder) which is made from grey cast iron was used to produce ductile iron using a crucible furnace that is fired by oil. Also, recycling of the grey cast iron to ductile iron was investigated and its effect on the microstructure, chemical composition, mechanical properties and chip shape. The mechanical and structural characteristics of the ductile irons that alloyed by the supplement of Ni, Mo, Mg, and Cr were studied In this study, four kilograms of the scrap were charged into an oil-fired crucible furnace. The scrap was heated to 1400°C with using a temperature controller to monitor the temperature with an inserted thermocouple. For desulphurization, the mixture of 3 wt.% burnt lime with 1 wt.% fluorspar of scrap weight was added to the molten at 1400°C by direct tapping into the molten. Then, 2.75 wt.% nickel element, 0.75 wt.% ferromolybdenum and 0.5wt.% ferromanganese of the scrap weight were added. Also, 1.25 wt.% spheroidizing alloy (FeSiMg9) and 1wt.% inoculant alloy of scrap weight were used to treat the iron melt at 1450°C. The analysis of scrap sample and product sample was done to determine their chemical composition, tensile strength, impact strength, hardness, and microstructure. The scrap and the as-cast product analysis determine its chemical composition, tensile, impact, hardness and microstructure. The microstructures revealed that the scrap contains flake graphite and the as-cast product contains spheroid graphite. An increase of the ultimate tensile stress (537.17 MPa), elongation (10%), hardness value (480.4 HB) and impact value (11.21 J) was observed for the alloyed ductile iron as compared with the mechanical properties of grey cast iron scrap, including (247.75 MPa), (6%), (400.3 HB) and (5.66 J), respectively. One of the important conclusions is the plunge container manufactured, and that was used according to the plunging technique followed in this investigation proved successful

Abstract: This research investigates the nickel content added by 1.1wt%, 2.2wt%, 3.7wt% and 4.5wt% on the microstructure and mechanical properties in the nodular cast iron. The results demonstrate that the microstructure of nickel addition consists of nodule graphite, ferrite and pearlite phase while nickel was added to 4.5 wt% the microstructure becomes ferrite transform to fully pearlite phase. In addition the ductile iron has the highest nodularity (0.79%), followed by 1.1%Ni (0.75%), 2.2%Ni (0.71%), 3.7%Ni (0.69%) and 4.5%Ni (0.58%). The hardness and tensile strength increase when increasing the nickel content. Elongation is enhanced with nickel increasing and reaches a maximum of 12% at 1.1 wt% Ni, then decreases with the further increase of nickel.

Abstract: Nodular graphite cast iron or known as spheroidal graphite cast iron structurally has a spherical graphite morphology with a matrix consisting of a ferrite-pearlite phase. In general, cast iron has a main alloy consisting of carbon and silicon where both elements have an influence on the potential of graphitization and castability. In this work, the influence of strontium (Sr) added to molten cast iron with a composition of 0, 0.04, 0.06 and 0.08 wt% to graphite morphology were studied. The sample obtained will be carried out a characterization process by observing macro and microstructures using optical microscope equipped with image data processing software that displays graphite fraction, size, form and nodularity. Analysis showed that Sr addition increase in nodularization of graphite from 19.6 % to 31.5% at 0.08 wt% Sr addition.

Abstract: Nodular cast iron is a type of cast iron with spheroid graphite surrounded by ferrite matrix and / or pearlite. The size of the graphite and its matrix affects the mechanical properties of the cast iron. This research was conducted to investigate the effect of Magnesium composition on strength, stiffness and toughness of nodular cast iron. Magnesium addition is performed by adding FeSiMg alloys. After that, the composition of magnesium was investigated by using spectrometry. Then tensile test was conducted to obtain the yield strength, tensile strength and modulus of elasticity. Further, impact test was performed to determine the impact energy needed to break the material. The result showed an increase of yield strength, tensile strength and stiffness and a decrease of toughness.

Abstract: This paper describes one possible method to anticipate and control the development of solidification shrinkage, during solidification of nodular cast iron melts, based upon industrial trials made using special designed test castings and closed volume thermal analysis cartridges.The methodology considers both the solidification morphology and solidification shrinkage critical size, which is always a difficult component of analysis, along with a developed contraction defect index, that allows the application to several types of molten metal and inoculation practices.The use of thermal analysis allows the recognition of unique melt characteristics, in real time, that are not accessed by more traditional measurement equipment. This allows the definition of thermal analysis patterns that characterize the best melt quality for self-feeding. This is a practical to use and powerful tool for modern foundries, taking advantage of new metric, data collection and data analysis. We aim to contribute to scientific knowledge and simultaneously to provide information that can be useful for foundries to improve their process efficiency.