چكيده به لاتين
The use of ductile cast iron parts with high casting modulus has increased due to low production cost, high casting capability and good combination of mechanical properties, especially in the windmill industry. Production of ductile cast iron parts with high casting modulus due to long solidification time and difficult control of microstructure is faced with many problems such as the formation of degeneration graphite, especially chanky graphite, shrinkage porosity, formation of brittle intercellular phases, and etc,which each Which of them causes a decrease in mechanical properties.
In this study, the effect of antimony and casting modulus on the microstructure, morphology of graphite, and mechanical properties of ductile cast iron was investigated. For this purpose, a ductile cast iron with chemical composition (weight percentage) of 3.3% carbon, 2.6% silicon, 0.3% manganese, 0.045% magnesium, in a mold containing three cylindrical foam models with Different modules castings of 8, 15 and 30 mm were cast. Also, in order to investigate the effect of antimony element in another mold with similar conditions before, 0.01 wt% of antimony was added to the mold while adding melt. Then microstructure was analyzed using a optical microscope. MIP4 image processing software was used to analyze microstructure images. To evaluate the mechanical properties, Brinell hardness and tensile tests were performed. The results of this study showed that with increasing the casting modulus, nodule count decreased from 500 to 235 nodule per square millimeter, also nodularity decreased from 71 to 63%. Also, the study of the results of hardness and tensile test shows that with increasing the casting modulus, the hardness decreases from 289 to 212 Brinell and the yield strength from 400 to 350 MPa. Comparison of samples containing antimony and without antimony showed that antimony increased the nodularity, nodule count and volume fraction of perlite. For example, for sample with 1 mm modulus, the presence of antimony increased the nodule count by 49%, improved the nodularity from 65% to 68. 75%, and also increased the perlite fraction by almost 11%.
