Study on Wear Resistance Property of Low-Alloy Chilled Ductile Cast Iron
Date Issued
2010
Date
2010
Author(s)
Chen, Ching-An
Abstract
The primary purpose of this research is study the effects of C and Si contents, solidification cooling rate (with and without chilling), and late inoculation on microstructure, hardness and wear resistance of ductile cast irons under fixed alloy compositions of 2.5%Ni-1.0%Cr-0.5%Mo-0.4%Mn. The experimental results show that, at a fixed CE of about 4.13%, increasing Si content (from 1.15% to 1.68%) increases graphite nodule count, but reduces both carbide and bainite contents. In addition, the employment of late inoculation (0.1% Fe-Si inoculant) increases nodule count, while slightly reduces carbide content. On the other hand, at a fixed Si content of some 1.46%, increasing C content (from 3.44% to 3.81%) increases both graphite nodule count and bainite content, but reduces carbide content. Late inoculation promotes bainite formation. Furthermore, when the alloy solidification cooling rate was increased by chilling, the microstructure exhibits increased graphite nodular count and carbide content, and also the carbides formed are more refined. As a result, the hardness is higher with a higher solidification cooling rate.
Regarding the pin-on-disc tests (Al2O3 as dics material), the results show that the chilled specimens exhibit higher wear loss compared with non-chilled specimens. By means of multiple linear regression analysis, wear loss is functions of nodule count and bainite content, with the nodule count being a positive effect, while the bainite content a negative effect. However, a reversed results on wear loss were obtained for pin-on-flat tests (S45C as stationary counter material). In summary, alloys with moderate nodule count and with a merely bainitic matrix can attain the best wear resistance. In addition, the wear resistance is affected more by varying Si content than by C content.
Subjects
Low-alloy ductile cast iron
Wear resistance
Chill
microstructure
Type
thesis
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