Stainless Steel CA40 H+T 540
Heat-treated state
ASTM CA40 · UNS J91153
H+T 540 = quenched, tempered 480–590 °C
Higher-strength option; avoid the 400–550 °C band where temper embrittlement and reduced corrosion resistance occur unless toughness is secondary.
Values for the H+T 540 condition
Other CA40 tempers and conditions
CA40 is listed in 6 conditions; see the grade overview at CA40.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — choose for rough machining of complex castings before final hardening. | 415 | 640 | 24 | 200 HB | — |
Normalized and tempered | Best-toughness heat treatment; use where impact and weld repair matter more than hardness. | 530 | 720 | 22 | 20 HRC | — |
H+T 650Default Austenitized 980–1010 °C, air/oil quenched, tempered 620–675 °C | Standard ASTM A743 CA40 supply condition — balanced 690 MPa-class strength with usable ductility and corrosion resistance. | 620 | 795 | 18 | 24 HRC | — |
As fabricated | Shipping/intermediate condition only — as-cast martensite is hard and crack-prone; always heat treat before service. | 650 | 900 | 5 | 43 HRC | 2.8 % IACS |
H+T 540This page Quenched, tempered 480–590 °C | Higher-strength option; avoid the 400–550 °C band where temper embrittlement and reduced corrosion resistance occur unless toughness is secondary. | 790 | 1,000 | 13 | 33 HRC | — |
Quenched, tempered 260–370 °C | Pick for wear surfaces, valve seats and pump wear rings where hardness ≥ 38 HRC matters and impact loading is low. | 1,000 | 1,300 | 7 | 41 HRC | — |
What is CA40 H+T 540?
CA40 H+T 540 is CA40 heat treated to H+T 540 — higher-strength option; avoid the 400–550 °C band where temper embrittlement and reduced corrosion resistance occur unless toughness is secondary. CA40 H+T 540 has a yield strength of 790 MPa (115 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 96% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi). CA40 H+T 540 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). H+T 650 is the default condition FabDigit quotes; H+T 540 is available on request or by drawing note.
Advantages
- Low embodied carbon — 2.9 kg CO₂/kg, better than 98% of stainless steel grades
- High strength — 790 MPa (115 ksi), better than 96% of stainless steel grades
- High electrical conductivity — 3 % IACS, better than 95% of stainless steel grades
- Conducts heat well — 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades
Limitations
- Needs corrosion protection — 33/100, worse than 98% of stainless steel grades
- Limited formability — 8/100, worse than 97% of stainless steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 95% of stainless steel grades
- Limited ductility — 13%, worse than 93% of stainless steel grades
- Difficult to weld — 28/100, worse than 90% of stainless steel grades
CA40 H+T 540 properties
Typical room-temperature values for CA40 H+T 540; 14 are specific to this condition. Other listed values are CA40 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CA40 H+T 540 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).
Mechanical16
CA40 H+T 540 has a yield strength of 790 MPa (115 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 96% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CA40 H+T 540 is rated for continuous service to 450°C (842 °F). It conducts heat at 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades. Thermal expansion is 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
CA40 H+T 540 conducts electricity at 3 % IACS, better than 95% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is poor (33/100), worse than 98% of stainless steel grades.
Sustainability4
Producing a kilogram of CA40 H+T 540 takes about 40 MJ of energy and emits 2.9 kg of CO₂ — less than 97% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
CA40 H+T 540's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability poor (28/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CA40 H+T 540
Is CA40 easy to machine?
Machine in the annealed or high-temper condition with rigid setups, sharp carbide (C2/C6) tooling, positive rake and generous flood coolant; above ~35 HRC switch to ceramic/CBN or grinding.
Can CA40 be welded?
Weldable only with care: preheat 200–315 °C, use 410/410NiMo or austenitic 309 filler, maintain interpass temperature, and temper immediately after welding to avoid hydrogen and quench cracking.
Can CA40 be formed, bent or molded?
Sand or investment cast with generous risering and controlled cooling; slow cool through the martensite range and stress-relieve/anneal before shakeout stresses cause cracking — no cold forming.
What surface finishes work on CA40?
Passivate per ASTM A967 after machining to restore the chromium oxide film; takes hard chrome plating, nitriding or a bright mechanical polish, but never anodize.
CA40 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 |
|---|---|---|
| Chigher C than CA15 — source of extra hardness | 0.2 – 0.4 | 0.3 |
| Mn | ≤ 1 | 0.6 |
| Si | ≤ 1.5 | 0.9 |
| P | ≤ 0.04 | — |
| SCA40F free-machining variant raises S deliberately | ≤ 0.04 | — |
| Cr | 11.5 – 14 | 12.8 |
| Ni | ≤ 1 | 0.5 |
| Moresidual; not intentionally added | ≤ 0.5 | — |
| Fe | balance | — |
CA40 H+T 540 — frequently asked
What is CA40 H+T 540 used for?
CA40 H+T 540 is typically used for valve seats and trim, wear rings, pump parts and cutlery-grade castings. In short: hardest standard CA grade; wear-resistant cast martensitic; lower toughness than CA15.
What is the yield strength of CA40 H+T 540?
CA40 H+T 540 has a typical yield strength of 790 MPa (115 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 96% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is CA40 H+T 540 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Machine in the annealed or high-temper condition with rigid setups, sharp carbide (C2/C6) tooling, positive rake and generous flood coolant; above ~35 HRC switch to ceramic/CBN or grinding.
Can CA40 H+T 540 be welded?
Not readily — weldability is rated poor (28/100). Weldable only with care: preheat 200–315 °C, use 410/410NiMo or austenitic 309 filler, maintain interpass temperature, and temper immediately after welding to avoid hydrogen and quench cracking.
What surface finishes work on CA40 H+T 540?
Passivate per ASTM A967 after machining to restore the chromium oxide film; takes hard chrome plating, nitriding or a bright mechanical polish, but never anodize.
Can CA40 H+T 540 be formed, bent or molded?
Sand or investment cast with generous risering and controlled cooling; slow cool through the martensite range and stress-relieve/anneal before shakeout stresses cause cracking — no cold forming.
What is the maximum service temperature of CA40 H+T 540?
CA40 H+T 540 is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CA40 H+T 650 and CA40-A?
H+T 650 is the default condition — standard ASTM A743 CA40 supply condition — balanced 690 MPa-class strength with usable ductility and corrosion resistance. A: softest condition — choose for rough machining of complex castings before final hardening. Yield strength is 620 MPa in H+T 650 versus 415 MPa in A.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- 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)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- GB/T 2100 / GB/T 8492 (ZG2Cr13 ) (2017)
- JIS G 5121 — Corrosion-resistant steel castings (SCS2A) — JSA (2003)
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.