ASTM A859 / A859M

This specification covers requirements for low-carbon age-hardening nickel-copper-chromium-molybdenum-columbium alloy steel forgings for pressure vessel components.Forgings under this specification are available as Grades A or B. Grade A may be ordered in one or two classes as follows:Grade A Class 1—Normalized-and-precipitation-heattreated,providing a minimum yield strength of 55 ksi [380 MPa] and a minimum tensile strength of 65 ksi [450 MPa].Grade A Class 2—Quenched-and-precipitation-heattreated,providing a minimum yield strength of 65 ksi [450 MPa] and a minimum tensile strength of 75 ksi [MPa].Grade A was the original steel composition in this specification. Although the material is readily weldable, welding procedures are of fundamental importance and must be such as not to affect adversely the properties of the material, especially in the heat-affected zone. It is presupposed that welding procedures will be suitable for the material being welded. Supplementary requirements, including those applicable in Specification A 788, are provided for use when additional testing or inspection is desired. These shall apply only when specified individually by the purchaser in the order.

Grade

Grade	Description
Grade A	-
Grade B	-

Chemical Properties

Grade	Carbon	Manganese	Phosphorus, max	Sulfur, max	Silicon, max	Chromium	Nickel	Molybdenum	Copper	Columbium	Vanadium, max	Aluminum max	Titanium max	Tin max	Arsenic max	Antimony max	Nitrogen
Grade A	0.07 max	0.40–0.70	0.025	0.025	0.40	0.60–0.90	0.70–1.00	0.15–0.25	1.00–1.30	0.02 min	-	-	-	-	-	-	-
Grade B	0.02–0.04	0.75–1.05	0.015	0.002	0.40	0.45–0.75	3.35–3.85	0.55–0.65	1.15–1.75	0.02–0.06	0.008	0.03	0.003	0.03	0.025	0.025	report