| 摘要 |
<p>PURPOSE:To obtain a machine tool or the like having high accuracy and excellent in function by constituting it of cast iron having a graphite structure, having a specified compsn. constituted of carbon of solid solution, Si, Ni, Co and Fe and having a low thermal expansion coefficient. CONSTITUTION:The compsn. of cast iron having a graphite structure in an austenitic base matrix is constituted of a one contg., by weight, 0.09 to 0.43% carbon of solid solution, <1.0% Si, 29 to 34% Ni and 4 to 8% Co and furthermore contg., at need, >=1.0% Mn and <=0.1% Mg, and the balance Fe. In this compsn., the cast iron whose thermal expansion coefficient in the temp. range of 0 to 200 deg.C is regulated to 4X10<-6>/ deg.C or below and simultaneously satisfying the characteristics such as castability, machinability and vibration absorption without deteriorating the mechanical strength can be obtd. By using this low thermal expansion cast iron, the machine tool, precision measuring instrument, molding die or the like having high accuracy and high performance can be formed.</p> |
