Papers by Keyword: Quality Index

Abstract: Cast aluminum alloys are an important group of materials which find wide application in the automotive industry. Insufficient studies have been carried out to date with regard to the mechanical performance of the aged A354 alloy. Therefore, the present work investigates the Quality index charts with the purpose of setting the limits of the tensile properties, as well as for comparing the mechanical behavior of cast alloy A354, to delineate the effect of the solution treatment applied. Tensile properties upon artificial aging in the temperature range of 155–350^oC for times ranging from 2 to 100 hours are also investigated. The results showed that the use of quality index charts is a satisfactory method for presenting tensile test results and, for assessing the effect of solution and aging treatment conditions subjected to the modified and grain-refined A354 alloys. It is also observed that the quality index, Q, is more sensitive to variations in the tensile ductility than to tensile strength.

Abstract: Cast aluminium alloy 354 has become an important industrial material owing to its excellent mechanical properties and good castability. It finds widespread use in the manufacture of compressor wheel castings. Castings have been studied since long and different approaches have been attempted to improve their quality. One such approach is Hot Iso-static Pressing (Hipping). This paper studies the effect of Hipping on the strength, ductility, strain energy density W and quality rating Q_o of the alloy 354. The study shows that Hipped samples have better % elongation to fracture, higher W and Q_o values as compared to non-Hipped samples. This behavior is consistent across different aging conditions of the alloy. Hipping also results in a reduction in scatter of ultimate tensile strength of 354, thus making it valuable to industries that demand high material consistency.

Abstract: Cast aluminium alloy 354 has found widespread application in the automotive industry for its excellent mechanical properties and good castability. The stringent emission norms and demands for improved fuel economy have pushed automobile technology to new frontiers. This has led to efforts to reduce weight while maintaining higher vehicle performance. Cast aluminium alloy 354 is a material that performs with reasonable effectiveness in the high stress automobile environment. The present study looks at the use of strain energy density W and the quality index Q_o to determine the effect of process parameters like aging temperature and modification on the quality of the alloy 354 and also to monitor the effect of interrupted heat treatments T6I4 and T6I6 on the quality of the material. The strain energy density W calculated for the interrupted heat treatments on alloy 354 show a broad inverse relation with yield strength R_p. An improvement in the yield strength and the strain energy density of the alloy is observed when the alloy is subjected to modification. At artificial aging temperatures lower than the artificial aging temperature adopted in standard aging treatment an improvement in the Qo and W quality of the alloy 354 have been observed.

Abstract: The effect of different solution temperatures has been investigated on the tensile properties of Na-modified Al-Mg₂Si in situ composite specimens which were subjected to solutionizing at different temperatures of 480 °C, 500 °C and 520 °C for holding time of 4 h followed by quenching. Tensile test results indicated that elongation value gradually increases upon solution treatment whereas ultimate tensile strength (UTS) reduces. The results of solution treatment also showed that the highest quality index is achieved in 500 °C (354 MPa) and so it is revealed optimum solutionizing temperature level (500 °C) for improving tensile properties.

Abstract: Selecting an aluminum die casting alloy for a particular application often poses a challenge to designers and engineers. It is often difficult and sometimes not possible to find an alloy that meets all the requirements of the application; and in other times the alloy can be found, but it has a wide specified compositional range, and thus it exhibits a large variation in properties. Therefore, there is always a need to optimize existing alloys or to develop new alloys so that they meet the requirements of a given application. In order to help with the alloy selection and alloy development processes, we developed an electronic database for aluminum die casting alloys – i-Select-Al. This software can help its user to quickly select an alloy for a specific application from a comprehensive list of commercial alloys. Alternatively, it can help its user with the design of a new alloy to meet the requirements of the application. This paper presents a study in optimizing A380 alloy with the help of i-Select-Al. A380 alloy is the most commonly used die casting alloy, but it has a wide compositional range and therefore a wide range of properties. In this study, we optimized the mechanical properties of A380 alloy by optimizing its chemical composition. The Quality Index was used to quantify the changes in the alloys’ properties in response to changes in chemical composition. Two alloys were designed: one has a composition within the A380 alloy specification, and the other has a composition slightly outside the A380 alloy specification. Both alloys showed significant improvements in room temperature tensile properties and a substantial increase in the Quality Index over a commercially available A380 alloy.

Abstract: The T5 heat treatment of semi-solid metal (SSM) processed alloy F357 was investigated by considering the effects of cooling rate and natural aging after casting, as well as artificial aging parameters on tensile properties. In addition, the tensile properties of SSM-HPDC F357 in different temper conditions (F, T4, T5 and T6) are compared. The Quality Index (QI) is used to compare the influence of different T5 heat treatment parameters and different temper conditions.

Abstract: In order to simulate the recrystallization process, Monte Carlo modelling has been applied to the case of wire-drawn copper deformed to a moderate strain. The complete experimental set of data was taken mainly from Electron Back Scattered Diffraction measurements in a Scanning Electron Microscope. Several nucleation hypothesis have been introduced and tested into the model. It has been shown that nucleation taking into account the sites associated with the highest stored energy and highest local misorientation leads to the best results in terms of recrystallization microstructure and texture. An important number of new orientations - that come only from annealing twinning - are not reproduced with the model, indicating the major role of this particular mechanism during the recrystallization process.

Abstract: Wire-drawn copper has been investigated with Electron Back Scattered Diffraction technique in a Scanning Electron Microscope after deformation by wire-drawing. In this paper, we show how to get qualitative informations about the deformation inhomogeneities related to the stored energy distribution, from the analysis of the quality index. Furthermore, the microstructural analysis in the wire diameter is completed using the quality index distribution approach. A relation between diameter of the wire and stored energy distribution is then qualitatively set. In order to validate the proposed method, the EBSD data are compared with the stored energy values obtained from neutron diffraction measurements.