Abstract
The effect of riser and chill arrangement on the soundness of sand-cast HK-40 steel (0.4%C-25%Cr-20%Ni) was studied experimentally. It was found that the size of risers should be about two times as large as that recommended by Pellini for plain carbon steel and that the end cooling distance and riser feeding distance were approximately equal to those found by Pellini on plain carbon steel. The effect of several foundry variables on the mechanical strength of steel at room temperature as well as at an elevated temperature was studied experimentally. It was found that strength decreased with an increase in section thickness and that the major cause for the decrease was a micro-constituent which precipitated during slow cooling after solidification, and not the casting defects nor crystal grain size. It was shown that much of the decrease of strength in heavy sections could be prevented by rapid cooling after solidification.
