The Influences of the Number of Graphite Nodules and Silicon Content on the Continuous Heating Transformation of Spheroidal Graphite Cast Irons

Abstract

  The influence of silicon content and number of graphite nodules on the continuous heating transformation of cast irons was studied by dilatometric and metallographic methods. The continuous transformation temperature Ac₁ rises with increasing rate of heating. The Ac₁ temperature rises greatly at higher rates of heating with decreasing the number of graphite nodules. When the silicon content is within the range of 1 to 3%, the Ac₁ temperature is shifted slightly upward as the silicon content increases both in ferritic and pearlitic initial matrices, and rapidly upward with still more silicon content. The Ac₁ temperature is higher in ferritic matrix than in pearlitic. The transformation time is shorter at higher heating rates and is somewhat affected by the silicon content.