does CF8M req. solution anneal to achieve 316 prop. 1

CF8M Heat Treatment: "Heat to 1900 F, hold for sufficient time to heat casting to temperature, quench in water or rapid cool by other means so as to develop acceptable corrosion resistance."
--I found the above in The Making, Shaping and Treating of Steel, 9th Edn., which cites ASTM A296-68, which has been replaced by ASTM A743/A743M (see link), which cites further standards (see excerpt below).

ASTM A743/A743M-98ae1 Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
"1.1 This specification covers iron-chromium and iron-chromium-nickel alloy castings for general corrosion-resistant application. The grades covered by this specification represent types of alloy castings suitable for broad ranges of application which are intended for a wide variety of corrosion environments.

Note 1-For alloy castings for severe corrosion-resistant service, reference should be made to Specification A744/A744M. For general heat-resistant alloy castings, reference should be made to Specification A297/A297M. For nickel alloy castings for corrosion-resistant service, reference should be made to Specification A494/A494M."

Castings need the solution anneal to ensure they are homogenious. Otherwise the casting will have segregation during solidification, which could produce preferential corrosion in the areas lean in alloying elements. If you want a solution anneal, specify that the casting be produced to ASTM/ASME A/SA351 Grade CF8M. The specification requires a solution anneal for all castings produced to the specification.

FYI, ASTM A351
"A351/A351M-00 Standard Specification for Castings, Austenitic, Austenitic-Ferritic (Duplex), for Pressure-Containing Parts"
"A number of grades of austenitic and austenitic-ferritic steel castings are included in this specification. Since these grades possess varying degrees of suitability for service at high temperatures or in corrosive environments, it is the responsibility of the purchaser to determine which grade shall be furnished. Selection will depend on design and service conditions, mechanical properties, and high-temperature or corrosion-resistant characteristics, or both."