Developing a workbook in excel that includes all formulas for machining. However, some of the material to be cut is cast and only minimum tensile strengths are given. What like some actual pulls to determine median of UTS. Want to make sure actually am shearing material. Cast are GM 238, 241, 245, 338. 238 is grey cast iron. 241 is alloyed cast iron. 245,338 are nodular (ductile) cast iron.