Abstract
Five types of ductile cast irons (DCIs) were fabricated by crystallizers with different inner diameters, as well as five different austempered ductile cast irons (ADIs) after the same isothermal quenching process. The effects of amount, diameter, and morphology of graphite on the mechanical properties of DCI and ADI and the effect of the original as-cast microstructure on the microstructure after austempering were studied. The microstructures were characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. Their mechanical properties were examined by tensile, U-shaped impact, and hardness tests. As the diameter of the crystallizer increases from 60 mm to 150 mm, the diameter of the nodular graphite increases from ~10 to ~50 μm, and the nodularity rate decreases from 100 to 70%. The average ultimate tensile strength increases from ~500 MPa in the as-cast state to 1100 MPa in the austempered state and the hardness increases from ~180 HB to 400 HB. The elongation in cast state decreases from 11 to 4.6% and the elongation in ADI state decreases from 7 to 4.5%. Through the research in this paper, it can be seen that ADIs with different matrix microstructures can be obtained from different original as-cast microstructures through the same isothermal quenching process, and different casting crystallizers can be selected according to different performance requirements, which can reduce the nitrite pollution and reduce cost.
Funder
Central Iron and Steel Research Institute independently invested in a special research and development fund
National Natural Science Foundation of China
Fundamental Research Funds for the Central Universities of China
VILLUM FONDEN
Subject
Inorganic Chemistry,Condensed Matter Physics,General Materials Science,General Chemical Engineering
Cited by
7 articles.
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