... carbon alloy steel 20MnTiB 2.Property Class:8.8 or 10.9s Standard:GB/T 1228-1231 ... Materials: low carbon alloy steel 20MnTiB2.Property Class:8.8 or 10.9s3.Appy to standard: ASTM ... Treatment: HDG, Zinc, Black... Carbon steel: Grade/class 4.8, 5.8, 8.8, 10.9, ... on.sizesAccording to clientsClassAccording to clientsShape of headSquare, or according to custmoers' requirementsSurface treatmentBlack, Hot-dip ...