... ~10. Outer diameter: 6~800mm Material: Mild steel, cast steel, cast iron, forged steel, stainless steel, alloy steel, plasitc, POM, aluminium alloy, zn alloy, bronze ... , brass, chrome, 40Cr, 20CrMnTi, Steel 1020, Steel 1045. Surface treatment: Carburizing, hardening and tempering, nitriding, high frequency treatment, black of oxidation ...