Φ12～32 mm 20CrMo齿轮钢（/%：0.19～0.23C,0.48～0.58Mn,0.24～0.28Si,0.009～0.015P,0.003～0.012S,0.87～1.08Cr,0.17～0.18Mo,0.024～0.046Als）的生......