Papers by Keyword: Casting Defects

Abstract: In this paper, both thixocasting and rheocasting of Al-7Si-0.6Mg alloy (EN AC 42200) for the same part was performed. It was found that rheocasting of Al-7Si-0.6Mg alloy show a smaller primary Al grain size and significant improvement of cast defects compared with thixocasting of Al-7Si-0.6Mg alloy. This paper demonstrates that rheocasting of Al-7Si-0.6Mg alloy is more beneficial in terms of microstructure and cast defects compared with thixocasting of Al-7Si-0.6Mg alloy.

Abstract: Welded arc welding repair welding technology was used to repair the casting defects of high chromium cast iron ball mill liners. Select the same high-chromium cast iron as the casting. The diameter of the electrode is 4mm and the welding current is 150-160A. After welding, the castings were found to have no cracks by surface non-destructive testing. The macro-hardness was comparable to that of the matrix material, and the microstructure showed that the fused surface was a good metallurgical bond.

Abstract: A new method of action on melts is proposed which is based on pulse-magnetic processing them with the aim to form a homogeneous fine-grained structure and improved technological properties of cast metal. The results of experimental researches of influence of main factors of treatment on the structure and properties of binary and commercial alloys of the system Al-Si are given.

Abstract: In today's competitive world the main direction of improvement of any production is the modernization of known technological processes and creation of new ones. A huge role in improving the process of manufacturing parts is played by computer and innovative technologies that allow to adjust technology to create the best quality castings at the lowest cost. All of this ultimately leads to saving materials, energy, labor time, protects equipment, and in return we get a lot of unique information about the process.

Abstract: EPC process, based on the casting structure, technical requirements, production volume, production conditions determines the casting solution, process planning. In this paper, the author from three aspects , the analysis of die casting process design principles, design principles and infiltration technology, makes a deeper understanding on the EPC process, and put forward some standards and requirements of the EPC process technology, which avoid the casting defects and waste caused by technical factors.

Abstract: Simulation tools have been effectively employed in many applications for numerically investigate on the development of efficient production processes aiming to materials quality enhancement. Such studies allow drastically reduction of the number of experimental tests and consequently of the development costs and further of the time-to-market. In this framework, the present paper focuses on the study of filling rate and of the solidification times of Titanium alloys. Starting from some acquired experimental data, considering appropriate boundary conditions and properly setting of the external parameters (flow-rate, liquid temperature, etc.), the study targets optimizing the processing cycle and reducing the presence of defects in casting. The cast tree used for the research is a symmetric one, including two samples used for Charpy impact tests and two samples for tensile tests. The considered commercial software provides a complete finite element solution and has been employed facilitating to prevent casting defects. During the simulations, the process parameters and the alloy properties have been explicitly taken into account. Information about how the parameters should be modified to achieve the optimal conditions close to a defects-free castings was achieved. A good correlation, in terms of microstructural analysis, between the simulation data and the experimentally obtained results was obtained, confirming the reliability of the model.

Abstract: Alloys from group Mg-Ag-RE-Zr are characterized by creep resistance up to 200°C, good casting and mechanical properties. Defects of magnesium alloys are propensity to cracks and deformations during heat treatment, low corrosion resistance. Welding technologies are most often use to repair of casts, mainly nonconsumable electrode welding in inert gas cover. About possibility repair or regeneration of magnesium alloy castings by welding depends on their weldability. Weldability of most magnesium alloys is good however, welding and surfacing cast elements create many problems. The purpose of this research work was develop a repair welding technology of casts magnesium alloy. Research project consisted of weldings and padding trials, microstructure and mechanical properties tests. Presented research results in this paper support conclusion that casts alloy QE22 reveal susceptibility to stable connection.

Abstract: Fracture surfaces of two sets of rotor blades failed after strong testing procedures of aircraft engines in the test-stand are investigated by means of SEM. While the process of fatigue fracture in the first set of blades did not reveal any defect features, both the initiation and propagation of fatigue cracks was strongly influenced by casting defects.

Abstract: Each casting produced in a foundry is a research experiment, since no two castings have the exactly same values of their geometric, material and process parameters. By the time, castings are inspected the link to the originating (influencing) parameters is lost, since they are never systematically recorded and correlated with quality characteristics. Thus, a valuable opportunity to improve casting quality is lost. In this work, we present a systematic approach for classifying casting defects by correlating them with the originating parameters; the proposed classification approach is hierarchical and more comprehensive. The defects are classified under geometry, integrity and property related defects. The defects analysis system includes an expandable library of images to facilitate correct identification of a given defect, and presents the various causes and remedies based on the user inputs. The entire system is being implemented in a web-based environment for wide access to practicing foundry engineers.

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.