Papers by Keyword: Ductile Iron

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Authors: W. Brevis, Luca Susmel, J.B. Boxall
Abstract: The present paper summarises an attempt of using the so-called Modified Wöhler Curve Method (MWCM) to estimate fatigue damage in pitted cast iron water pipes subjected to in-service variable amplitude multiaxial fatigue loading. In this setting, pits are treated as hemispherical/hyperbolic notches whose depth increases over time due to conventional corrosion processes taking places in buried cast-iron pipes. The validity of such an approach is proven by showing, through a case study, that, under particular circumstances, the combined effect of corrosion and fatigue can remarkably shorten the in-service lifetime of cast-iron pipes as observed in the case study.
Authors: Werner Menk
Abstract: Years ago, especially in Sweden, a new family of ductile iron materials was propagated: Solid solution strengthened ferritic ductile iron. Since the 2011 edition, three grades are integrated into the European Standard EN 1563: EN-GJS-450-18, EN-GJS-500-14 and EN-GJS-600-10. The introduction of these materials into the European standard generated a large interest of many engineers, which came to a real hype meanwhile. The reason is clear: While GJS-450-18 is not very different from the standard GJS-400-15, especially the grade EN-GJS-500-14 promises to have big advantages compared to the standard grade EN-GJS-500-7. Same tensile strength, from 320 MPA to 400 MPa raised 0.2%- proof strength and from 7% to 14 % doubled elongation after fracture are very interesting properties of course and the pure ferritic structure promises a better machinability furthermore. With the higher strength grade EN-GJS-600-10 very early sceptic comments raised, because the Silicon content to reach the required strength is such high, that the risk of an embrittlement of the ferrite even at room temperature and on a tensile test bar is high. But up to now, the grade EN-GJS-500-14 has the reputation to be a high strength and very high ductile material. So, a customer of us also substituted a part from steel to EN-GJS-500-14. All calculations showed a very good performance of the parts, but as soon as in serial production field damages occurred in a manner that the parts completely broke without advance warning. The investigation of the damages showed, that the parts are not only statically and cyclically loaded, but also by strikes. Deeper investigations about strike loads confirmed, that EN-GJS-500-14 is not really ductile under these conditions. The reflection to the philosophy we had with our SiboDur-700 concept, namely to combine a moderate solid solution strengthening with a moderate strengthening by pearlite with Copper, brought us to a new high strength high ductile material we call SiboDur-500. Same strength as EN-GJS-500-14, 10 % lower in 0.2%- proof stress, slightly lower in elongation after fracture, but double to more than four times energy consumption at strike loads depending om temperature!
Authors: Hua Hou, Guo Wei Zhang, Hong Kui Mao, Jun Cheng
Abstract: Based on the solidification features of ductile iron and affecting factors for ductile iron shrinkage defect, the model of the ductile iron solidification is built and put forward a new defect predictive method EIECAM (Enclosed-Isolated area Expansion and Contraction Accumulation Method) model to predict defect. in DECAM, the liquid shrinkage, solidified shrinkage and graphitizing expansion during solidification are computed dynamically in the enclosed-isolated area , and the effect of graphite expansion on the wall movement is also accounted. Based on this method end cover of QT500 ductile iron casting is simulated and made the defect predictive, study its solidification process and the defect generation position, and make the experimental identification on the defect. It is resulted that the method can be able to predict the casting defect authentically.
Authors: Vasilios Fourlakidis
Abstract: This paper investigates the effects of graphite added as a conditioner, of Lantanum containing nodulariser and of pouring temperature on the formation of shrinkage porosity in ductile iron casting with an eutectic composition. In this experiment for each heat the cooling curves were recorded by the use of Quick-Cups (thermal analysis cups) and different solidification parameters such as TElow, GRF1, GRF2 and TS were calculated and compared with the porosity which was found from the microstructure examination. The results show that there is a good correlation between the amount of the shrinkage formation and the thermal analysis values. Also this experiment confirm that by using certain treating elements and pouring temperature which was between 1340-1350°C it is possible to eliminate the shrinkage defects in ductile iron castings without using feeders.
Authors: P.K. Oke, O.K. Ukoba
Abstract: Ductile Iron has been a great material in water carrying pipes, heavy duty parts of farm equipment and other heavy applications. This work looked into the corrosion rate of ductile iron in different environments of usage and storage for a period of six (6) months. The environments were outside air, air conditioned (A/C) environment, brackish (salty) and alkaline environments. The results showed that as the period of exposure increases the corrosion rate decreases. There was a sharp corrosion rate at the first few months for all the environments but as the month increases the corrosion slows down. Brackish (NaCl) environment had the highest weight loss with a difference (last month initial month) of 1.1456g followed by outside environment with a difference of 1.0284g while A/C had the lowest with zero.
Authors: Azalan Mohamed Ibrahim, Mohd Azam Musa, Noraishah Mohamad Noor, Wan Ahmad Najmudin Wan Saidin, Mohd Fadhil Rani
Abstract: This paper presents analysis of Micro-Porosity defect in product Crankshaft - Ductile cast iron (FCD 700/2), which has been carried out at one of Automotive Foundry Company in Malaysia. Systematic analyses like cause-effect diagram and defect diagnostic study approach were carried out to understand the root causes of the micro-porosity. From the data analysis there are two significant factors are identified that affect the formation of micro-porosity, they are mold factor and metal factor. Four remedial countermeasures have been proposed to prevent micro-porosity; increase squeezes pressure at molding machine, control sand moisture, increase radius at edge of mold, and reduce Magnesium (Mg) content. Result of the trials showed substantial reduction of micro-porosity defect in crankshaft (casting). The company has accepted the countermeasure and incorporated in the standard operation procedure.
Authors: P.K. Oke, O.K. Ukoba
Abstract: The problem of engineering materials failing in structures like bridges, pipelines, refinery and automobile equipments is becoming a source of concern to the people of the developing nations especially Nigerians. This sometimes might be attributed to the environments in which the materials are being used or stored and the source of the materials. There is a need therefore, to evaluate the effects of these environments on the final property, especially the mechanical properties of the materials. Based on the peculiarity of ductile iron (DI) having its application in most engineering works in different environments, the material was subjected to four different environments namely alkaline (NaOH), brackish (NaCl), air conditioning (A/C), and outside environment, coinciding with the environments of application. The material was later subjected to series of mechanical tests and the behavioural changes (especially the mechanical property) of the materials in these environments were monitored for the period. It was observed that the ductile iron placed outside had the highest elastic properties and hardness of 1341.72Hv while alkaline environment had the highest strength of 3321.75MPa. The alkaline environment gives the highest performance as it had a quality index of 4,038,837, followed by outside environment while salty environment had the least.
Authors: M.M. Cisneros-Guerrero, R.E. Campos-Cambranis, M. Castro-Román, M.J. Pérez-López
Authors: K. Shimizu, T. Noguchi, Toshiro Kamada, S. Doi
Authors: E.K. Ampaw, E.K. Arthur, O.O. Adewoye, A.R. Adetunji, S.O.O. Olusunle, Winston O. Soboyejo
Abstract: In this paper, ductile iron was produced using a rotary furnace. The microstructures of the ductile iron (with and without cyanided coatings) were then characterized using optical microscopy, scanning electron microscopy (SEM) and energy diffraction X-ray spectroscopy (EDS). The surfaces of the ductile iron were then subjected to high temperature carbonitriding using a pack cementation process in which carbon and nitrogen were diffused into the ductile iron from powder mixtures consisting of ground cassava leaves and barium carbonate (BaCO3) energizers. The wear behavior of the coated and uncoated ductile iron was studied using the pin-on-disk method. The wear mechanisms were also elucidated using a combination of SEM and EDS. The mechanisms of wear were also studied using nanoscratch experiments. The resulting wear rates are then compared with those from micron-scale wear tracks obtained from pin-on-disk experiments. The implications of the results are then discussed for the design of wear resistant ductile irons.
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