MICROSTRUCTURAL CHARACTERIZATION OF LOW CARBON STEEL USED IN AIRCRAFT INDUSTRY

Abstract

Results regarding the microstructural and thermal analysis of etched low carbon steel samples collected from the local steel industry are presented. The effect of varying etching time or concentration of the etchant was also investigated. The microstructural analysis was carried out using scanning electron microscope (SEM). Differential thermal analyzer (DTA), thermo-gravimetric analyzer (TGA) and thermo dilatometric analyzer (TDA) were used for thermal analysis. Mechanical properties of the samples were determined using Universal Testing Machine (UTM). The mechanical properties indicated that the specimen was in the range of low carbon steel (probably AISI 1015) i.e. highly ductile, malleable and soft. DTA indicated the phase transformation temperatures to magnetic and then to non-magnetic FCC phase to be 727°C to 770°C and 910°C consistent with previous studies. For SEM imaging, constant composition etchant for 45 seconds and altered composition etchant for 8% nitric acid in ethanol were found to be best for the examined samples.