Elastic Behaviour of High-Density Powder-Forged Samples of Iron and Iron-Graphite

A brief review of the theoretical dependence of the elastic constants on density is presented followed by a series of experimentally derived data for powder-forged Fe and Fe–0·3%C components. The elastic constants were measured in a number of ways including 3- and 4-point slow bend tests, gauged tensile tests, and sonic resonance and ultrasonic pulse time methods. The resonance data correlate well with final fracture energy, indicating that sonic data are potentially useful NDT parameters. The differences between the results from the various methods are discussed and it is shown that, even at less than half the yield stress, elastic properties are dependent on test strain. It is suggested that this dependence is due to microstructural features inherent in powder-based samples. The apparently anomalous behaviour of an as-sintered sample is explained in terms of these features.