Characterization of the Electrical Discharge Machined M300 Maraging Steel Flexures Using Nanoindentation

Abstract

Gyroscope is an orientation determining sensor whose performance is mainly dependant on one of the critical element called the gimbal flexure. Thinner the flexure, better is the performance. To have sufficient strength, M300 maraging steel is used to fabricate the thin flexures machined by Electrical Discharge Machining (EDM) process down to the required thickness of 0.05 mm in various stages. After the EDM processing, the recast layer formed can cause degradation in the microstructure and mechanical properties. Micro-abrasive machining was carried out to remove the recast layer. An attempt was made to understand the changes that occurred after EDM and after micro-abrasive machining with respect to the microstructure using optical and Scanning Electron Microscopy (SEM) and with respect to mechanical properties using nanoindentation. Nanoindentation technique was adopted as the recast layer was just few microns thick. Indentations were carried out on the base material, as EDM cut flexure, and the micro-abrasive machined EDM cut flexure to obtain elastic modulus and hardness values for each condition and the results were analyzed.