アルミニウムを含む耐熱性マグネシウム処理鋳鉄に関する研究

抄録

  In this report, scaling and growth charactristics as well as mechanical properties of high purity cast iron treated with metallic magnesium containing about 3.5%C, 2.5%Si and up to 7.7%Al were investigated.
  In the scaling test carried out under the heating conditions of 900°C in air for a total of 100 hours the scaling resistance properties of 1.00%Al specimen was slightly superior to the base specimen without Al (0.007%Al), but 1.46%Al and 3.47%Al specimens were remrakably superior.
  In the growth test carried out by a repetition of the heating-cooling cycles 6 times within the temperature range of 600°C to 900°C in the air and measureing the amount of growth in each cycle at 600°C, 1.46%Al specimen showed slight growth, but 3.47%Al and 7.67%Al specimens showed no growth at all. On the permanent growth which appeared when the specimens were air-cooled from 600°C to room temperature after the above mentioned test, the influence of aluminium was quite similar to that the heating-cooling cycle test.
  The mechanical properties of the 2.8%Al specimens which has 54% spheroidization of graphite was tensile strength 40.3kg/mm², elongation 2.5% and BHN about 170. On the other hand, ternary carbide Fe₃AlC_X (ε-phase) appeared in the matrixes of as cast specimens containing above 3.5%Al which remained even after annealing for the heat-resistance test. 1.5%∼3.5%Al specimens which have considerably good mecanical properties, i. e., 40∼38kg/mm² tensile strangth, 3∼2% elongation and 170∼150BHN, showed remarkably good scaling and growth resistant properties.
  These results will be helpful in the production of heat-resistant cast irons.