HB-YD688(Q)1.650-60用于磨煤辊打底焊(韧性好，可以多层堆焊)Usedtocoalrollerbackingwelding.HB-YD788(Q)1.655-62硬度高，可以多层堆焊。Highhardnessandmulti-layerweldingHB-YD888(Q)1.2,1.660-65硬度高，堆焊层厚度不超过6mm。Highhardness,butthethicknessofsurfacinglayerislessthan6mm.)