Rheological and Thermal Characterization of AISI 4605 Low-Alloy Steel Feedstock for Metal Injection Molding Process

Abstract

In this study, rheological and thermal decomposition behavior of AISI 4605 MIM feedstock investigated using capillary and thermogravimetric analysis. For this purpose and in order to find the critical solids loading, the feedstock was prepared by compounding AISI 4605 micro powder (similar to 4 mu m) with an adopted multi-component wax-based binder system at various powder loadings (53-61 vol%). After preparing the feedstock with optimal solids loading, fundamental rheological characteristics of homogenized feedstock, including flow behavior index (n), flow activation energy (E), and general moldability index (alpha(stv)) were studied. Furthermore, thermal analysis of feedstock, including apparent debinding activation energy and master decomposition curve was investigated. The results showed that critical solids loading of feedstock is around 58 vol%. The flow behavior index of developed feedstock was acceptable, since it came out to be less than one. Also, flow activation energy which shows the sensitivity of material to temperature changes, came out to be 70.406 kJ/mol. Using these two parameters, general moldability index was calculated to be 2.3147E-06. Finally, the master decomposition curve of feedstock was constructed based on calculated apparent debinding activation energy and verified using decomposition curves at different heating rates of 2, 5 and 10 degrees C/min. Graphic