Factors affecting mechanical properties of GGG 40.3 (Low-temperature impact-resistant ductile cast iron)

摘要

Professional Metallurgical Services conducted impact tests, tensile tests and chemical analysis on 83 ductile iron Y-blocks as part of an on- going project for Giddings and Lewis. Further analysis of this test data was conducted using statistical analysis. Metallographic analysis on selected samples was also conducted to evaluate the effects of a cerium addition. The purpose for this analysis was to determine the factors that most influenced the impact and tensile properties The statistical analysis indicated that none of the elements had a correlation with elongation for the composition range represented with the 83 samples. Individually, the elements silicon, aluminum and, perhaps, molybdenum had a limited correlation with average impact strength. However, using multiple regression analysis, a relatively good correlation with elongation existed when the elements carbon, manganese, silicon, copper, nickel, chromium, molybdenum and aluminum were considered. These same elements in combination exhibited a strong correlation factor with average impact strength, considering that the information was from production data. The conclusions from this analysis indicated that, as the silicon content increased, the aluminum content increased, almost linearly. Since, individually, silicon had a relatively high correlation factor with average impact strength, the influence of the inoculant distribution was thought to have a major effect on the resulting impact strength. Subsequently, additional studies indicated that distribution of the inoculant was not uniform. Y-blocks that were placed in the mold runner system ahead of the mold cavity contained more silicon from the inoculant than Y-blocks placed in the mold runner system after the mold cavity. It was also concluded from this analysis that the tramp element level was influencing the impact property results.