Grinding cylpebs specification Ball diameter(mm) 10 12.7 15 17 20 25 30 40 50 60 70 80 90 100 110 120 125 130 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 -