Papers by Keyword: Shrinkage Cavity

Abstract: Shrinkage cavity and shrinkage porosity, often occurring during the production of heavy v-belt pulley roughcast, may lead to the decrease of the pulley performance and further result in casting rejection. Therefore, it is necessary to study the causes and prevention measures of shrinkage defects of the casting. The material of V-belt pulley roughcast at issue is HT250 and it adopts resin sand casting process. With a large amount of practice in workshop and times of revision of the design of foundry technology, we have found that the shrinkage in the hot spot of heavy v-belt pulley roughcast can be reduced or even eliminated to fully meet the performance requirements with a moderate control of pouring temperature and speed, an optimized design of foundry technology, and a strict limitation of chemical composition. This finding will bring illumination to the production process of other heavy pulley roughcast.

Abstract: There are many advantages in producing forklift box through the LFC. However, we found shrinkage porosity defects in the interior of castings through simulating the original process by ProCAST casting simulation software. Therefore, we analyzed the defects and improved the technology program. firstly, increased riser in position of shrinkage, Secondly, changed the filling’s way, lastly, selected the best temperature and vacuum by the orthogonal experiment and determined the best technology solution. we found the shrinkage porosity defects have been removed by the improved process. We found the production consistent with the simulation results through verification. Therefore we verify the accuracy of the ProCAST.

Abstract: The rump pan is the body and the load-carry device of Scraper conveyer. the material is ZG30MnSi. In order to improve the life of the casting.this paper simulated filling and solidification process of rump pan by Procast software,and predicted the position of shrinkage cavity and shrinkage porosity in castings.Then through improving gating system and add reasonable risers, optimal process parameters scheme is got.

Abstract: In order to achieve high quality superalloy ingots, an investigation of applying linear electromagnetic stirring to the superalloy vacuum casting solidifying process has been put into effect with electroprobe microanalysis and optical microscope. The results indicate that an one sided, upward linear electromagnetic stirring with 50Hz frequency and 140A current can effectively refine the isometric crystals and shorten the ratio of central shrinkage cavity in superalloy ingots.

Abstract: Electric pulse current (EPC) was employed to treat ZA27 alloy cast in the sand mould during the solidification. The experiment results indicated that the shrinkage cavity and the porosity in the ZA27 alloy was apparently reduced. And correspondingly, the mechanical properties of the castings were certainly improved. The current pulse applied in the initial stage of the solidification produced a better treatment result. The density of the casting ZA27 alloy treated with EPC in initial stage and later stage increased by 4.1 and 1.6 percent than that without EPC, respectively.

Abstract: Copper tube produced by FA6502 copper alloy in a company of Wuhan appears shrinkage cavity in horizontal continuous casting, the graphite mold core which exerts stretching effects is easy to be snapped in production process. The reason why shrinkage cavity appears is found through large number of experiments and analysis. Then we adjust the component of FA6502 copper alloy, the quality of new copper alloy FA6506 is improved significantly. Furthermore, we find the reason why the graphite mold core is snapped in production process, FA6502 copper alloy’s shrinkage rate is too large in solidification. The compact power of the graphite mold core is too large to bear, too much resistance in pulling process is exerted so that the graphite mold core is snapped.

Abstract: The effects of titanium modification, which was added along with the pouring liquid in ladles, on the shrinkage porosity and cavity of cast steel ZG45 smelted in intermediate frequency induction furnace were studied. The metal liquid fluidity was measured by casting spiral samples. 0.2 wt.% titanium modification achieved the highest fluidity for steel liquid. Proper content of titanium could effectively increase the volume of concentrated shrinkage cavity, and restrain the forming of shrinkage porosity. By scanning electron microscope (SEM) and energy disperse spectroscope (EDS) analysis, it was found that TiC, acting as heterogeneous nuclei, could refine the structure grains, diminish the strong dendrite, and increase the fluidity and feeding capacity of steel liquid. However, overdoes titanium modification easily caused mass oxide TiO2, which kept solid phases with high meting point in metal liquid to increase its viscosity and decrease the fluidity. Meanwhile, these solid state titanium compounds enlarged the composition supercooling, so the metal liquid changed from sequential solidification to simultaneous solidification, resulting in inadequate metal liquid feeding, less oncentrated shrinkage cavity and serious shrinkage porosity.

Abstract: The effects of titanium modification, which was added along with the pouring liquid in ladles, on the shrinkage porosity and cavity of cast steel ZG35 smelted in intermediate frequency induction furnace were studied. Proper content of titanium could effectively increase the volume of concentrated shrinkage cavity, and restrain the forming of shrinkage porosity. The concentrated shrinkage cavity was analyzed quantitatively by stuffing wet gluten and draining water method. The maximal cavity arrived at 0.15wt.% titanium modification. By scanning electron microscope (SEM) and energy disperse spectroscope (EDS) analysis, it was found that TiC, acting as heterogeneous nuclei, could refine the structure grains, diminish the strong dendrites, and increase the fluidity and feeding capacity of steel liquid. However, overdoes titanium modification easily caused mass nitrides or oxides, which kept solid phases with high meting point in metal liquid to increase its viscosity and decrease the fluidity. On the other hand, these solid state titanium compounds enlarged the composition supercooling, so the metal liquid changed from sequential solidification to simultaneous solidification, resulting in inadequate metal liquid feeding, less oncentrated shrinkage cavity and serious shrinkage porosity.

Abstract: Shrinkage cavity/piping at the end of the solidified ingot of steels is one of the most common casting problem in 316L austenitic stainless steel ingot, when consumable electrode is melted and cast in a water-cooled copper mould by vacuum arc re-melting furnace. In present study an effort has been made to reduce the size of shrinkage cavity/ piping by establishing the optimum value of hot topping process parameters at the end of the melting process. It is concluded that the shrinkage cavity/piping at the top of the solidified ingot can be reduced to minimum by adjusting the process parameters particularly the melting current density.

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.