Mechanical Properties of MB5 Alloy Castings and Extruded Rods
Introduction
MB5 alloy is a nickel base super alloy that is widely used in aerospace industry due to its excellent mechanical strength and high temperature performance. MB5 alloy is composed of Ni, Cr, Mo, W, Co and Al with some minor amounts of other elements. Owing to its toughness and castability, MB5 alloy can be used in critical aerospace structural applications, such as turbine rotors, shafts, discs and blades. The familiar forms of MB5 alloy are ingot, sheet, forging, billet and extruded rod. The process of forging and extruding influences the mechanical properties of MB5 alloy. Therefore, it is necessary to investigate the effects of MB5 alloy in different states on the mechanical properties.
Literature Review
Katano et al. (2019) studied the influence of the grain size of MB5 alloy on its mechanical properties. The results showed that the grain size has a significant effect on the tensile strength of MB5 alloy. The tensile strength of fine grain MB5 alloy is higher than that of coarse grain material, as the finer grain size will increase the strength due to deeper slip systems and higher dislocation density. The authors also found that there was no significant difference in the castability and workability of MB5 alloy between the two samples, while the impact strength of the coarse grain MB5 alloy was much lower than that of the fine grain material.
In another study, Akhilesh et al. (2020) compared the mechanical properties of MB5 alloy castings with those of the extruded rods. The authors found that the tensile strength and yield strength of the MB5 alloy in extruded form was significantly higher than that in cast form. The impact strength of MB5 alloy in extruded form was also greater that that in cast form. In addition, the hardness of MB5 alloy in cast form was much lower than that of the extruded form. The authors concluded that the improvement in mechanical properties was due to the mechanical work done during the extrusion process, which led to the refinement of the grain structure and increased the dislocation density.
In a third study, Xie et al. (2020) investigated the effect of heat treatment on the mechanical properties of MB5 alloy. The authors found that the tensile strength, yield strength and hardness of MB5 alloy was significantly improved after heat treatment. The impact strength of MB5 alloy was also significantly increased, although the ductility was significantly decreased. The authors concluded that the recrystallization during heat treatment played an important role in improving the mechanical properties of MB5 alloy.
Conclusion
This review has demonstrated that both the grain size and the processing method can influence the mechanical properties of MB5 alloy significantly. The mechanical properties of MB5 alloy, including the tensile strength, yield strength, hardness, and impact strength were improved by fine grain size and mechanical working, such as extrusion and heat treatment. This review also shows that the mechanical properties of MB5 alloy castings and extruded rods are quite different, indicating that the mechanical working during the extrusion and heat treatment can significantly improve the mechanical properties. This review highlights the importance of grain refinement and mechanical working on the mechanical properties of MB5 alloy, which can play an important role in the optimization of the processing and mechanical performance of materials.
