Casting Alloy Comparison Chart

Direct answer: The most common casting alloys group into three families: carbon steels (A216 WCB/WCC for general service, A352 LCB/LCC for low temperature), chromium-moly alloy steels (A217 WC6/WC9 for elevated temperature), and austenitic stainless steels (A351 CF8 = 304, CF8M = 316 with molybdenum for chloride resistance). Select by matching alloy class to your service medium, temperature, and required strength, then confirm the exact ASTM minimums for the grade.

How to Read This Chart

Every value below is an ASTM specification minimum — the guaranteed floor a qualified casting must meet, not a typical test result. Use these numbers to specify and rate parts; actual properties usually exceed them. Pick a family by service environment first, then choose the grade by temperature and strength, and always confirm the current ASTM edition for the exact figures.

Casting Alloy Comparison Chart

Values are ASTM minimums for castings; verify against the current standard edition before specifying.

What Tensile, Yield & Elongation Tell You

Three numbers drive most casting selection. Tensile strength is the maximum stress the material withstands before fracture — a ceiling, useful for comparing grades but rarely the design limit. Yield strength is where permanent deformation begins; it is the number pressure-boundary design actually leans on, because a valve or pump body must not yield under rated pressure. Elongation measures ductility — how much the metal stretches before breaking — and is a proxy for toughness and forgiveness under shock or thermal cycling. A high-yield grade with low elongation can be strong but brittle, which is exactly why low-temperature service adds impact testing on top of these minimums.

For castings specifically, remember these are foundry minimums on separately cast test bars; section thickness, solidification rate, and heat treatment all influence the properties in the actual part, which is why qualified foundries control melt practice and verify with mechanical and NDT testing.

Stainless Steel Cast Grades (A351)

The austenitic stainless grades are the corrosion workhorses. CF8 (cast 304) handles general corrosion and a very wide temperature band, from cryogenic to about +649 °C. CF8M (cast 316) adds roughly 2–3% molybdenum, which sharply improves resistance to pitting and crevice attack in chlorides and chemical media — the default choice for seawater, chemical, and chloride service. The low-carbon variants CF3 and CF3M trade a little high-temperature strength for better weldability and resistance to sensitization. For a deeper treatment, see our stainless steel casting grades guide.

Carbon & Low-Temperature Grades (A216 / A352)

WCB is the standard carbon steel casting grade for non-corrosive water, oil, and gas from about −30 to +425 °C; WCC offers higher yield strength for the same service window. Below roughly −20 °F, plain WCB can turn brittle — so for cold service you specify LCB or LCC under A352, which mandate Charpy impact testing at the design minimum temperature to guarantee toughness down to around −46 °C.

Chromium-Moly Alloy Steels (A217)

When the service is hot enough that carbon steel would creep, chromium-molybdenum alloy steels take over. WC6 (1.25Cr-0.5Mo) and WC9 (2.25Cr-1Mo) add creep strength and oxidation resistance for steam, power-generation, and refinery service, with WC9's higher chromium suiting the higher temperatures. Both carry a 485 MPa minimum tensile and 275 MPa minimum yield.

Specialty Alloys: Duplex & 17-4PH

Beyond the common grades, two specialty families appear in demanding castings. Duplex stainless (ASTM A890, e.g. grade 4A / CD3MN) combines austenitic and ferritic structure for high strength plus excellent chloride pitting and stress-corrosion resistance — common in seawater and sour service. Cast 17-4PH (ASTM A747 CB7Cu-1) is a precipitation-hardening martensitic stainless that reaches very high strength after heat treatment while keeping moderate corrosion resistance. Both are specified separately, with properties set by the chosen heat-treat condition rather than a single minimum — confirm the exact grade and condition with your foundry.

How to Select a Casting Alloy

Work in this order:

• Medium & corrosion — benign fluids: carbon steel (WCB/WCC). Chlorides/chemicals: CF8M or duplex. General corrosion: CF8.
• Temperature — cold service: LCB/LCC. Hot/creep: WC6/WC9. Wide band: austenitic stainless.
• Strength — need more yield: WCC, LCC, or the Cr-Mo grades; very high strength: cast 17-4PH.
• Weldability — prefer low-carbon CF3/CF3M to resist sensitization.

Then confirm the ASTM minimums for the chosen grade and pressure class. Our team can cross-check the selection against your valve casting or process requirements.

Not sure which casting alloy your part needs?

Tell us the service medium, temperature, and pressure class. Our metallurgists will recommend the right cast grade and confirm the ASTM minimums for your application.