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Open Access Dissertation

Keywords

Cast-iron--Carbon content; Ductile iron--Carbon content;

Abstract

The purpose of this study was to determine what relationships exist between the chemistry and the morphology and nodular formation of carbon nodules in commercially produced ductile cast iron. Additionally, the effects of chemistry on the hardness of produced castings from net shake processes were investigated. According to pertinent information in current literature, the hardness of castings has a direct bearing on the final cost of products.

The method of gathering this information and developing a correlation between the chemistry variations and the morphology and nodular formation was facilitated by the cooperation of a commercial producer of ductile cast iron located in the midwest United States. The foundry supplied the chemical analysis sheeets. The samples were supplied from a commercial foundry. What was missing was a correlation between the chemistry analysis and the morphology and the nodular formation of ductile iron products.

The methodology involved included gathering the raw cast samples from the foundry, cutting, grinding and polishing the samples to a degree suitable for metallographic viewing and observation under a 100X microscope. The preparation, grinding and grading were all done using guidelines established by the American Society of Metals (ASM) in order to maintain continuity with industry-recognized grading methods.

Forty-seven sample Y-shaped blocks were acquired and sectioned to obtain an equal number of Y-shaped sections from the center of the test sample which was 1 inch thick. These sections were further cut into three vertical portions comprising the bottom, center, and tops of the Y-section. Through these procedures, 141 samples were now made available. Subsequent evaluation and testing resulted in the elimination of the center portions of the Y-sections due to unacceptable levels of gaseous porosity in these samples. As a result, 94 samples comprising the tops and bottoms of the Y-sections were judged suitable for retention for testing.

Test results were performed in correlation with a Carbon Equivalency number which was calculated from the chemistry evaluation sheets supplied by the foundry. The use of the Pearson Product Moment Correlation Coefficient to match the test result to the Carbon Equivalency number produced a series of correlations which were expressed as both numerical values and visual figures as graphic representations of the relationship between the Carbon Equivalency number and the Morphology, Nodular Formation, and the rated Brinnell Hardness of the samples.

Conclusions reached indicated that the Carbon Equivalency number appears to be of limited value in predicting the performance of the five dependent variables, under consideration during the course of the study. Reasonably reliable predictions appear possible for each of the dependent variables of Nodular count per square millimeter, percent Vermicular carbon per square millimeter, Nodular Sizes developed and the percent Nodularity per square millimeter. On the other hand, Brinnell Hardness numbers appear to be relatively stable and flat, with little variation shown as the Carbon Equivalency number increases or decreases. Therefore, the Carbon Equivalency number, while of limited value in predicting the first four dependent variables, is of no real value for the fifth (BHN) variable, leaving the foundry wit the task of reevaluating other prediction methods for the Brinnell Hardness of finished castings.

Year of Submission

1989

Degree Name

Doctor of Industrial Technology

Department

Department of Industrial Technology

First Advisor

Mohammad F. Fahmy (Advisor)

Second Advisor

John T. Fecik (Co-Advisor)

Date Original

7-1989

Object Description

1 PDF file (viii, 123 pages)

Language

en

File Format

application/pdf

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