고용강화 페라이트계 구상흑연주철의 미세조직 및 기계적 성질에 미치는 합금원소의 영향

Abstract

The use of aluminium materials have been in rise with increase in demand in electric vehicle market for weight reduction, resulting decrease in demand of ductile cast iron. To solve this problem, research on weight reduction of cast iron parts has been widely conducted by reducing thickness of the parts or making them into hollow structure. For those thin and hollow automotive parts, new ductile cast iron with enhanced mechanical properties is necessary. Typical alloy design method of ductile cast iron controls pearlite fraction of the alloy matrix to increase tensile strength of ductile cast iron by adding so-called austenite stabilizing elements but it decrease elongation. In this sense, solid solution strengthened ferritic ductile cast iron (hereafter, SSF DI) was intensively studied due to excellent tensile properties with high Si content. For the development of high strength-high elongation ductile cast iron, this study confirmed the microstructure and mechanical properties at different Ni and Cu contents. C and Si content is controlled close to carbon equivalent 4.3 To Estimate tensile strength properties and brinell hardness, respective experiments were done with the prepared specimens. Furthermore, Optical microscopy and image analysis program were used to analyze microstructure. According to change in chemical composition, relationship of microstructure and mechanical properties was investigated. In addition the property prediction model equation use to the correlate between the measured data.