Abstract
In order to decide the most suitable method to take the samples of cast iron used for chemical analysis, we prepared six square bars which were cast in sand mould of various sizes (10×10×100-100×100×100mm).
Each bars were cut from the center and twelve analytical samples taken from the outer and inner layers of them by drilling. Investigation was made on the influence of the particle size and of the rate of cooling on chemical composition of cast iron. We further made a metallurgical consideration from the relation between microscopic structure and mechanical properties.
The results were:
(1) The difference of chemical composition between the bars with the largest cross section and the bars with the smallest cross section is remakable. Namely, it is obvious that the chemical composition of cast iron is much effected in the structure of it. In other words, the rate of solidification as well as the rate of cooling after solidification play on important part in the change of structure.
(2) Therefore, the white cast iron on which the change in the structure is very small indicates the standard value of chemical analysis.
(3) In the gray cast iron, results of chemical analysis are much effected by the sampling method. However in any way, the coarse particles nearly indicate average value for chemical analysis, and the fine particles indicate marked defference.
From the results of above experiments, it was found that the analytical results of each compositions of cast iron is much influenced by the particle sizes of shavings as well as the structure of specimens, and the coarser particle size than the particle size of 20 mesh indicates the standard values of chemical analysis. Further as a result of the comparative studies on the various methods of sampling of cast iron, it was confirmed that the most simple method of would be to analyse the coarse particles which were obtained by drilling with a 1-in. dia large-angle-edge (about 150°) drill at about 80r.p.m.
