Elastic and Plastic Properties of Soda Lime Glass by Micro-Indentation

Brittle cracking in a residual impression can be observed during micro indentation testing of brittle materials. The formation of these cracks in the residual impression depends upon the nature of materials, geometry of indenter, testing load, dwell time and depth of penetration. The area adjacent to the cracks may be appearing either as raised up or sunk down at the edges. This plastic residual impression can be used to obtain various elastic and plastic properties of brittle materials such as shear strength, fracture toughness, crack resistance, surface strength, etc. In present work Soda Lime Glass was studied by micro indentation test carried on Vickers hardness testing method using diamond pyramid indenter. Indentations were obtained on glass using different loads with different dwell times. These indentations generated micro cracks on surface. It was observed that on low values of load no visible cracks were found but on increasing the load the nucleation of crack started its critical value. On further increasing the load the steady growth of crack was observed. The dwell time also affects the propagation of the crack, as the dwell time increased the crack propagation shifts toward higher values. Results were analyzed in the form of load versus crack size for different dwell times focusing on the onset of crack propagation. The results obtained during study were applied to relate various elastic and plastic properties of Soda Lime Glass.