The Position Statistic Distribution Analysis Techniques In The Analysis Of The Billet

This study introduces Single Discharge Analysis (SDA) ,a new technique with which a stand spark source opitical emission spectrometer is modified to allow sample movement and digitalized single discharge mersurements.A quantitative method for contious scanning analysis with SDA is estabilished and the concept of defect analysis with emission spectrometeris proposed.Application of SDA,including the data processing,defect calibrating and result expressing aspects, has been simultaneously researched in three areas, a) the influnces of temperature changes and oxidization of the sample, b) center—line segregation determination and mapping of samples and, c) defects detection, distinguishing and calibration.In this study, a set of billets has been tesred with the technique under discussion and the results demonstrate that the detection and distinguish of defects in a considerable large area is achievable and the measurement of segregation in serveral elements is satisfactory. The results also offer some potential advantages for setting up some objective indexes of segregation and porosity of cast sample.The study on the mechanism of single discharges of electric pulse applied to the tested sample shows that there are multi-discharges in every pulse and both the energy and location of each discharge follow the Gauss distribution. These analytical results prove that the technique of SDA under non-pre-burn condition is scientific. Not only is the concentration of elements measured but also the original state of the sample is determined. The new technique makes analytical results more accurate than those of the traditional integrate methods. Moreover, using the continuous concentration distribution on the sample surface as an index to expressing the segregation can be more representative and precise than typical individual sampling method.With SDA, intensity decreasing of the reference line can be used to detect defects on sample surface,such as porosity and shrinkage.Shrinkage can even be located and sized by the mapping methods of SDA. Furthermore, with the statistics of the intensity ratio below the maximum frequency of the reference, it is possible to qualify the porosity on cast sample by an objective index.