however the alloys of the present invention have better machinability at any hardness level than the prior art non austenitic alloys this point is illustrated by the fact that alloys of the invention of less than about 340 bhn in the as cast condition h 997 h 1010 and h 1013 all of 321 to 325 bhn could be drilled by ordinary 1 4 inch diameter high speed tool steel bits whereas the prior art pace alloy having about the same hardness as those alloys of the invention immediately blunted the high speed drill bits and could not be drilled except by the cemented carbide bits obviously there are cost saving advantages in using alloys of the invention since they can be machined in the as cast state without expensive heat treatment pre machining preparation on the other hand from inspection of the hardness data in table iii it is evident that the alloys of the invention will have good abrasion resistance in corrosive abrasive slurries while erosion resistant castings are typically machined in some areas of the castings the major portions of the castings surfaces in contact with slurries are left in their as cast surface condition which retains the mold sand imprint therefore aside from the small smooth ground area at the ingate entry portion of each test block casting surface.