| The experimental technique reproduces the continuous cooling conditions that occur in typical sinter-hardening processes and permits the determination of the sinter-hardening of powder mixes as a function of material and process variables, particularly the cooling rate after sintering and the density of the parts. The method uses a sample with a relatively simple geometry subjected to different temperature-time cycles in order to simulate sintering cycles, particularly the cooling rate after sintering. Thermocouples are embedded in different areas of the sample in order to determine precisely the local cooling rate in these regions. The cooling rates are then related to the apparent hardness and the microstructure characterized in the same areas for which the cooling rate was determined, thereby permitting construction of apparent hardness-cooling rate-microstructure processing diagrams. These experimental results are then modeled to derive a mathematical expression to predict the apparent hardness of sinter-hardened parts as a function of cooling rate, density and carbon content of the parts. (Abstract shortened by UMI.)... |
