... ASTM A519 ProcessRaw materials- Cold drawn/rolled- Heat treatment(BKS)- Honed or SRB- packingSteel GradeST52/E355, ck20, ck45, 34CrMo4, SAE 1026 ... Test, Blow Test, Impact Test etc), Exterior Size InspectionSKYPE: samsonhuang22 honed tubes for hydraulic and pneumatic cylinder