1) 20 Marks A metallographic sample suitable for examination using inverted optical light microscopy and/or scanning electron microscopy is to be prepared from a mild steel component using the following sequence of steps: cutting a sample from the component using consumable abrasive cutting; cold- mounting the as-cut sample in epoxy resin; grinding the sample surface on successively finer grades of Sic abrasive paper; polishing the sample surface on successively finer grades of diamond paste on a rotating polishing cloth; and finally etching the surface in dilute acid. a) The step of consumable abrasive cutting can be critical in terms of the damage it imparts to the steel at the cut surface. What is this damage and how is it caused? In practice, how can this damage be minimised during consumable abrasive cutting? 6 Marks b) What is the purpose of mounting the cut sample in epoxy resin? 2 Marks c) Describe the process of grinding and the mechanism of material removal. 4 Marks d) Describe the process of polishing and the mechanism of material removal. 4 Marks e) What is the purpose of etching? 2 Marks 1) State two important requirements that the resultant metallographic sample ideally should have. 2 Marks