Stainless Steel 1.3960-AC (Spheroidize annealed)
Heat-treated state
EN 1.3960
Only for non-corrosive structural or ornamental use — carbide/sigma networks reduce ductility and intergranular corrosion resistance.
Values for the AC condition
Other 1.3960 tempers and conditions
1.3960 is listed in 4 conditions; see the grade overview at 1.3960.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
STDefault Solution annealed | Standard supply condition for all corrosion service — dissolves carbides/sigma and restores full intergranular corrosion resistance. | 275 | 550 | 45 | 155 HB | — |
solution treated and hot isostatically pressed | Choose for pressure-retaining or fatigue-critical castings where shrinkage microporosity must be closed. | 285 | 570 | 50 | 158 HB | 2.2 % IACS |
ACThis page Spheroidize annealed | Only for non-corrosive structural or ornamental use — carbide/sigma networks reduce ductility and intergranular corrosion resistance. | 290 | 520 | 28 | 170 HB | 2.1 % IACS |
centrifugally cast (ASTM A451/A452 practice), solution treated | Tubular/ring parts: denser, finer-grained wall with higher strength than static castings. | 300 | 585 | 42 | 165 HB | 2.2 % IACS |
What is 1.3960-AC?
1.3960-AC is 1.3960 heat treated to AC — only for non-corrosive structural or ornamental use — carbide/sigma networks reduce ductility and intergranular corrosion resistance. 1.3960-AC has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 72% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 192 GPa (27.8 Msi). 1.3960-AC has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,385°C (2,525 °F). ST is the default condition FabDigit quotes; AC is available on request or by drawing note.
Limitations
- Limited formability — 12/100, worse than 93% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
1.3960-AC properties
Typical room-temperature values for 1.3960-AC; 22 are specific to this condition. Other listed values are 1.3960 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.3960-AC has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,385°C (2,525 °F).
Mechanical16
1.3960-AC has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 72% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 192 GPa (27.8 Msi).
Thermal6
1.3960-AC is rated for continuous service to 550°C (1,022 °F). It conducts heat at 13.5 W/m·K (7.8 BTU/hr·ft·°F), worse than 83% of stainless steel grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
1.3960-AC conducts electricity at 2.1 % IACS, worse than 73% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.3960-AC takes about 55 MJ of energy and emits 5.2 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
1.3960-AC's machinability is poor (33/100, worse than 57% of stainless steel grades); weldability good (62/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.3960-AC
Is 1.3960 easy to machine?
Gummy and work-hardening: use rigid setups, sharp positive-rake carbide, heavy positive feed to cut under the hardened skin, 60–110 m/min with flood coolant.
Can 1.3960 be welded?
Very good weldability with GTAW/SMAW using 317L/ER317L (or overalloyed 309LMo for dissimilar joints); no preheat, interpass <150 °C, and re-solution-treat critical corrosion parts after major weld repair.
Can 1.3960 be formed, bent or molded?
Supplied as sand, investment or centrifugal castings — control gating/risering for the wide freezing range and hold 3–12 % ferrite (FN) to limit hot cracking; not a cold-forming grade.
What surface finishes work on 1.3960?
Pickle and passivate (ASTM A967 / A380) after grinding or weld repair; electropolishing gives the best pitting resistance — no anodizing.
1.3960 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 |
|---|---|---|
| Cextra-low carbon for intergranular corrosion resistance | ≤ 0.03 | 0.02 |
| Si≤1.0 % in EN GX2CrNiMoN grade | ≤ 1.5 | 1 |
| Mn | ≤ 1.5 | 1 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| CrASTM CG3M 18.0–21.0; EN 17.0–19.0 | 17 – 21 | 18.5 |
| NiASTM CG3M 9.0–13.0; EN grade ~12.5–14.5 | 9 – 14.5 | 13 |
| Modrives pitting resistance (PREN ≈ 30–36) | 3 – 4 | 3.3 |
| Nnitrogen alloyed in the EN GX2CrNiMoN version; optional in ASTM CG3M | 0.1 – 0.2 | 0.15 |
| Fe | balance | — |
1.3960-AC — frequently asked
What is 1.3960-AC used for?
1.3960-AC is typically used for chemical process pumps, valve bodies and marine fittings. In short: cast 317L pitting resistance; weldable without post-anneal; step up from CF3M.
What is the yield strength of 1.3960-AC?
1.3960-AC has a typical yield strength of 290 MPa (42.1 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 72% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 1.3960-AC easy to machine?
Not especially — machinability is rated poor (33/100, worse than 57% of stainless steel grades). Gummy and work-hardening: use rigid setups, sharp positive-rake carbide, heavy positive feed to cut under the hardened skin, 60–110 m/min with flood coolant.
Can 1.3960-AC be welded?
Yes — weldability is rated good (62/100). Very good weldability with GTAW/SMAW using 317L/ER317L (or overalloyed 309LMo for dissimilar joints); no preheat, interpass <150 °C, and re-solution-treat critical corrosion parts after major weld repair.
What surface finishes work on 1.3960-AC?
Pickle and passivate (ASTM A967 / A380) after grinding or weld repair; electropolishing gives the best pitting resistance — no anodizing.
Can 1.3960-AC be formed, bent or molded?
Supplied as sand, investment or centrifugal castings — control gating/risering for the wide freezing range and hold 3–12 % ferrite (FN) to limit hot cracking; not a cold-forming grade.
What is the maximum service temperature of 1.3960-AC?
1.3960-AC is rated for continuous use to about 550°C (1,022 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.3960-ST and 1.3960 CENT-ST?
ST is the default condition — standard supply condition for all corrosion service — dissolves carbides/sigma and restores full intergranular corrosion resistance. CENT-ST: tubular/ring parts: denser, finer-grained wall with higher strength than static castings. Yield strength is 275 MPa in ST versus 300 MPa in CENT-ST.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium-Nickel, Corrosion Resistant (grade CG3M) — ASTM International (2019)
- EN 10283 — Corrosion resistant steel castings — CEN (2010)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Steel Founders' Society of America / ACI cast stainless steel property data — SFSA (2015)
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.