The standard number A646/A646M-17 refers to a specific set of guidelines and specifications for a versatile steel grade. This steel grade is known for its promising properties and is used in various applications. The chemical composition of this steel grade is specified in the standard, outlining the elements and their respective percentages that make up the alloy. Additionally, the mechanical properties of the steel grade are also detailed in the standard, highlighting its strength, hardness, ductility, and other relevant characteristics. The corresponding A646/A646M-17 provides further details and information regarding the properties and applications of this steel grade.