ASTM A511 Standard Specification for Seamless Stainless Steel Mechanical Tubing and Hollow Bar.ASTM A511 Standard specification covers seamless stainless tubing for use in mechanical applications where corrosion-resistant or high-temperature strength is needed. ASTM A511 Standard main steel grade:ASTM A511 MT 430,MT 410,MT347,MT 321,MT 317,MT 316L and so on.