Inspection of casting defects and grain boundary strengthening on stressed Al6061 specimen by NDT method and SEM micrographs

Abstract

Non-destructive testing is one part of the function of quality control and is complementary to other long-established methods. By definition, non-destructive testing is the testing of materials, for surface or internal flaws or metallurgical condition, without interfering in any way with the integrity of the material or its suitability for service. The methods covered are Radiography, Magnetic Particle Crack Detection, Dye Penetrate Testing, Ultrasonic Flaw Detection, Eddy Current and Electro-Magnetic Testing. Here in this project work by using the radiography method of NDT testing is followed to identify the internal defects of the Al6061 cast specimen that was made by stir casting method. The aluminum cast structure involved to mono and multi-heat treated at about 450 °C and 600 °C in a muffle furnace and is compressed mechanically by using hydraulic press arrangements before the brief inspection through NDT testing. This technique is suitable for the detection of internal defects in ferrous and nonferrous metals and other materials. Furthermore, the denser the material greater will be the absorption. After the primary stage of inspection, most of the defects were identified by the NDT methods. In the second part of this project, SEM images can be taken for the compressed casting structure. The structural changes were successfully made on the cast specimen and the bond strength, as well as hardness were also increased. The comparison was made between the NDT inspected values and the SEM microstructure. It shows the clear representation of the grain structure and the bond strength. Keywords: Casting, Nondestructive testing, Hardness, SEM, Hot forming