Stainless Steel CA15-AC (Spheroidize annealed)
Heat-treated state
ASTM CA15 · UNS J91150
Rough/blank castings shipped before heat treatment; properties highly variable and not code-acceptable.
Values for the AC condition
Other CA15 tempers and conditions
CA15 is listed in 6 conditions; see the grade overview at CA15.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for heavy machining or before final hardening; not a normal delivery condition for pressure parts. | 415 | 655 | 26 | 180 HB | — |
NT650Default N&T | Default commercial condition for pump/valve castings: best combination of toughness, corrosion resistance and code compliance. | 510 | 700 | 22 | 20 HRC | — |
ACThis page Spheroidize annealed | Rough/blank castings shipped before heat treatment; properties highly variable and not code-acceptable. | 620 | 800 | 8 | 31 HRC | 2.9 % IACS |
Q&T | Choose when higher strength than the standard N&T condition is needed with acceptable toughness (impellers, wear rings). | 690 | 830 | 18 | 26 HRC | — |
Q&T | Maximum strength/wear resistance for non-corrosive, non-impact duty; toughness and corrosion resistance are reduced. | 900 | 1,100 | 11 | 37 HRC | — |
Hardened | Intermediate state only — maximum hardness but brittle and crack-prone; must be tempered before service. | 1,100 | 1,450 | 4 | 46 HRC | 2.8 % IACS |
What is CA15-AC?
CA15-AC is CA15 heat treated to AC — rough/blank castings shipped before heat treatment; properties highly variable and not code-acceptable. CA15-AC has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi). CA15-AC has a density of 7.61 g/cm³ (0.275 lb/in³), lighter than 96% of stainless steel grades. It melts at 1,480°C (2,696 °F). NT650 is the default condition FabDigit quotes; AC is available on request or by drawing note.
Advantages
- High strength — 620 MPa (89.9 ksi), better than 88% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- Low embodied carbon — 3.6 kg CO₂/kg, better than 83% of stainless steel grades
- Conducts heat well — 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades
Limitations
- Limited ductility — 8%, worse than 99% of stainless steel grades
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Needs corrosion protection — 35/100, worse than 97% of stainless steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 95% of stainless steel grades
- Difficult to weld — 25/100, worse than 92% of stainless steel grades
CA15-AC properties
Typical room-temperature values for CA15-AC; 22 are specific to this condition. Other listed values are CA15 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CA15-AC has a density of 7.61 g/cm³ (0.275 lb/in³), lighter than 96% of stainless steel grades. It melts at 1,480°C (2,696 °F).
Mechanical15
CA15-AC has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CA15-AC is rated for continuous service to 400°C (752 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
CA15-AC conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), worse than 97% of stainless steel grades.
Sustainability4
Producing a kilogram of CA15-AC takes about 40 MJ of energy and emits 3.6 kg of CO₂ — less than 97% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
CA15-AC's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability poor (25/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CA15-AC
Is CA15 easy to machine?
Machine in the annealed or high-tempered condition with rigid setups, sharp carbide tools, positive rake and generous coolant; work-hardens and gums less than austenitic grades but abrades tooling above ~30 HRC.
Can CA15 be welded?
Weldable with matching 410/E410 or austenitic 309/309L filler; preheat 200–315 °C, keep interpass warm, and post-weld temper at 620–760 °C to avoid hard, crack-prone HAZ martensite.
Can CA15 be formed, bent or molded?
Sand or investment cast; needs good risering (solidification shrinkage ~4 %), slow cooling from pouring, and mandatory austenitize+temper cycle to remove as-cast brittleness.
What surface finishes work on CA15?
Passivate per ASTM A967 after machining; hard chrome, electroless nickel or nitriding improve wear; avoid tempering in 400–550 °C which embrittles and lowers corrosion resistance.
CA15 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C0.15 % max per ASTM A743/A217 | ≤ 0.15 | 0.12 |
| Mn | ≤ 1 | 0.6 |
| Si1.00 % max in ASTM A217 | ≤ 1.5 | 0.8 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Cr | 11.5 – 14 | 12.5 |
| Ni | ≤ 1 | 0.5 |
| MoMo may be present from scrap; capped at 0.50 % | ≤ 0.5 | 0.3 |
| Fe | balance | — |
CA15-AC — frequently asked
What is CA15-AC used for?
CA15-AC is typically used for pump casings, valve bodies and trim, compressor parts and turbine components. In short: baseline 12Cr cast martensitic; heat-treatable pump/valve grade; moderate corrosion resistance.
What is the yield strength of CA15-AC?
CA15-AC has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 88% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is CA15-AC easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Machine in the annealed or high-tempered condition with rigid setups, sharp carbide tools, positive rake and generous coolant; work-hardens and gums less than austenitic grades but abrades tooling above ~30 HRC.
Can CA15-AC be welded?
Not readily — weldability is rated poor (25/100). Weldable with matching 410/E410 or austenitic 309/309L filler; preheat 200–315 °C, keep interpass warm, and post-weld temper at 620–760 °C to avoid hard, crack-prone HAZ martensite.
What surface finishes work on CA15-AC?
Passivate per ASTM A967 after machining; hard chrome, electroless nickel or nitriding improve wear; avoid tempering in 400–550 °C which embrittles and lowers corrosion resistance.
Can CA15-AC be formed, bent or molded?
Sand or investment cast; needs good risering (solidification shrinkage ~4 %), slow cooling from pouring, and mandatory austenitize+temper cycle to remove as-cast brittleness.
What is the maximum service temperature of CA15-AC?
CA15-AC is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CA15-NT650 and CA15-H?
NT650 is the default condition — default commercial condition for pump/valve castings: best combination of toughness, corrosion resistance and code compliance. H: intermediate state only — maximum hardness but brittle and crack-prone; must be tempered before service. Yield strength is 510 MPa in NT650 versus 1,100 MPa in H.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application (Gr. CA15) — ASTM International (2019)
- ASTM A217/A217M — Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts (Gr. CA15) — ASTM International (2021)
- ASTM A487/A487M — Steel Castings Suitable for Pressure Service — ASTM International (2020)
- Steel Castings Handbook, Supplement 8: High Alloy Data Sheets Corrosion Series — Steel Founders' Society of America (2004)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 2100 / GB/T 6967 — (ZG12Cr13 ) — SAC (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.