Characteristics of rare earth metal treated graphite cast steel.

In order to develop a free machining cast steel which has higher elastic stiffness and strength than cast iron, rare earth metal (REM) treated graphite cast steels were developed and its characteristics were investigated. REM treated graphite cast steel has more finely and uniformly distributed spheroidal graphite than cast iron or graphite cast steels treated with Ca or Mg. REM treated graphite cast steel which contains 1.0%C and 2.4%Si has the finest graphite distribution. This graphite cast steel has good machinability nearly equal to that of nodular graphite cast iron FCD45 as well as high rigidity nearly equal to conventional carbon steel. This cast steel is superior to nodular graphite cast iron with respect to fatigue strength and impact strength