ASTM A351 Standard Specification for Castings, Austenitic, for Pressure Containing Parts

Get Certified ASTM A351 for Reliable Austenitic Steel Castings

The ASTM A351 Standard is relied upon by foundries to verify that austenitic steel castings can withstand the pressure and/or temperature to which the item will be subjected when in service, whether it is a valve, flange, or fitting. Consistent testing from heat to heat ensures that grade certification is meaningful and reduces the risk of a casting failure when it is subject to the pressure of process fluid. Matestlab offers calibrated tensile and chemical composition testing to the process with analysts who fully understand how to validate austenitic castings to ASTM A351.

The scope of ASTM A351 includes:

• Material type: Austenitic steel castings made by the electric furnace process, with or without separate refining.
• Purpose: Establishment of chemical composition and tensile property requirements for pressure-containing austenitic steel castings.
• Property evaluation: Tensile strength, yield strength, elongation, and chemical composition specific to the ordered grade.
• Testing method: A tension test verifies mechanical properties, while heat and product analyses confirm chemical composition against the ordered grade.
• Results: Compliance determination against the chemical and mechanical limits stated for the ordered grade.
• Test limitation: Grades CE20N, CF3A, CF3MA, and CF8A carry a service ceiling of 800 °F (425 °C) due to thermal instability.
• Use conditions: Every casting receives heat treatment followed by a water quench or another rapid cooling method.
• Application: Supports valves, flanges, fittings, and other pressure-containing parts in high-temperature and corrosive process service.

What are the Uses of ASTM A351 Testing?

ASTM A351 testing helps foundries confirm that austenitic steel castings meet the chemical and mechanical requirements a pressure-containing part needs. Engineers use the results to pick the right grade for the temperature and corrosive conditions a valve, flange, or fitting faces. This standard-

• Confirms tensile strength, yield strength, and elongation for the ordered grade.
• Verifies chemical composition against the limits set for each austenitic grade.
• Supports quality control across casting production heats.
• Assists engineers in selecting a grade suited to high-temperature or corrosive service.
• Compares castings from different foundries against the same requirements.
• Flags grades unsuited to elevated-temperature service before installation.

Which materials can be tested under ASTM A351?

ASTM A351 covers the Austenitic steel castings used for various valves, flanges, fittings, and pressure-containing parts in a broad grade family. Carbon steel, low alloy steel, and duplex stainless steel castings are not covered by this specification, but each is covered by its own specification. The grades CE20N, CF3A, CF3MA and CF8A are only suitable for service up to 800 °F (425 °C), at which point their thermal instability will be a concern.

Why is ASTM A351 Important?

The ability of an austenitic casting to resist cracking or loss of strength under years of service in high temperatures or corrosive conditions is determined by grade selection. If a casting is cast beyond the temperature limit for its grade – for example, beyond 800 °F (425 °C) for CF8A – it could be thermally unstable at the very moment when a process line is looking for stability. Testing by the ASTM A351 standard ensures the consistent quality of reliable castings from different foundries, and helps ensure that pressure-containing parts are safe and code compliant.

ASTM A351 Testing Process and Data Collection

A technician selects a representative casting or test coupon from the production heat and confirms the ordered grade. The casting goes through heat treatment and a water quench or rapid cool, then a technician machines a tension specimen and pulls it to determine tensile strength, yield strength, and elongation. Chemical analysis confirms the composition elements the ordered grade specifies. A foundry compiles the chemical and mechanical data into the casting’s compliance record.

Common Challenges and Troubleshooting

Grade misapplication ranks high on the list of issues with austenitic castings, since pushing a thermally unstable grade like CF8A past 800 °F (425 °C) sets up problems that do not show up until the part is already in service. Inconsistent quenching speed after heat treatment causes its own trouble, leaving mechanical properties short of the ordered grade’s tensile strength or elongation requirement. Foundries stay ahead of these problems by matching grade to service temperature before casting, controlling quench timing and medium closely, and running chemical analysis before mechanical testing begins.

• Analysts report tensile strength and yield strength in ksi or MPa, such as a 70 ksi (485 MPa) minimum tensile strength and a 30 ksi (205 MPa) minimum yield strength for Grade CF8.
• Technicians measure elongation as a percentage over a standard gage length, commonly a 35% minimum for Grade CF8.
• Engineers flag any casting ordered in Grades CE20N, CF3A, CF3MA, or CF8A for service above 800 °F (425 °C), since thermal instability rules those grades out at that range.
• Analysts document chemical composition results for elements such as chromium, nickel, and molybdenum against the ordered grade’s limits.
• A foundry references both ASTM A351 and the ordered grade on the compliance record.

Link to ASTM A351