Grinding cylpebs specification Ball diameter(mm) F10 F12.7 F15 F17 F20 F25 F30 F40 F50 F60 F70 F80 F90 F100 F110 F120 F125 F130 Chemical coposition Zqcr2 C Si Mn Cr Mo P S 2.2-3.5 0.3-1.4 0.2-1.5 0.3-3.0 1.0 0.15 0.15 Properties and microstructure Designation Hrc Impact value(j/cm2) Microstructure Times of falling balls Zqcr2 46 1.5 P+c 15000 z