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Description / Abstract:
This specification covers requirements for low-carbon
age-hardening nickel-copper-chromium-molybdenumcolumbium 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 A788/A788M, are provided for use when additional
testing or inspection is desired. These shall apply only when
specified individually by the purchaser in the order.
The values stated in either SI units or inch-pound units are to
be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall
be used independently of the other. Combining values from the two
systems may result in non-conformance with the standard.
This specification is expressed in both inch-pound and SI units.
However, unless the order specifies the applicable "M"
specification designation [SI units], the material shall be
furnished to inch-pound units.