Steel X12CrMo5 +I (Isothermally annealed)
Heat-treated state
EN X12CrMo5
Choose for maximum machinability of forgings/bars before final heat treatment, or where only ASTM A182 F5 minimum properties are required.
Values for the +I condition
Other X12CrMo5 tempers and conditions
X12CrMo5 is listed in 3 conditions; see the grade overview at X12CrMo5.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+IThis page Isothermally annealed | Choose for maximum machinability of forgings/bars before final heat treatment, or where only ASTM A182 F5 minimum properties are required. | 320 | 530 | 25 | 165 HB | — |
+NTDefault Normalized and tempered | Standard supply condition for pressure-retaining forgings, flanges and valve bodies working 400–600 °C; balanced strength, toughness and creep life. | 460 | 660 | 21 | 17 HRC | — |
Quenched and tempered | Choose for high-strength bolting, studs and heavy valve trim where minimum yield above ~420 MPa is specified; tempering above 650 °C keeps creep and temper-embrittlement behaviour acceptable. | 540 | 720 | 18 | 22 HRC | — |
What is X12CrMo5 +I?
X12CrMo5 +I is X12CrMo5 heat treated to +I — choose for maximum machinability of forgings/bars before final heat treatment, or where only ASTM A182 F5 minimum properties are required. X12CrMo5 +I has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 81% of steel grades. Elongation at break is 25% and the elastic modulus is 213 GPa (30.9 Msi). X12CrMo5 +I has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,425°C (2,597 °F). +NT is the default condition FabDigit quotes; +I is available on request or by drawing note.
Advantages
- High service temperature — 550°C (1,022 °F), better than 95% of steel grades
- Good corrosion resistance — 25/100, better than 92% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Low electrical conductivity — 3 % IACS, worse than 91% of steel grades
- Low strength — 320 MPa (46.4 ksi), worse than 81% of steel grades
X12CrMo5 +I properties
Typical room-temperature values for X12CrMo5 +I; 16 are specific to this condition. Other listed values are X12CrMo5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
X12CrMo5 +I has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
X12CrMo5 +I has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 81% of steel grades. Elongation at break is 25% and the elastic modulus is 213 GPa (30.9 Msi).
Thermal6
X12CrMo5 +I is rated for continuous service to 550°C (1,022 °F). It conducts heat at 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 71% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
X12CrMo5 +I conducts electricity at 3 % IACS, worse than 91% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 92% of steel grades.
Sustainability4
Producing a kilogram of X12CrMo5 +I takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 35%.
Manufacturability8
X12CrMo5 +I's machinability is good (60/100, better than 83% of steel grades); weldability fair (45/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with X12CrMo5 +I
Is X12CrMo5 easy to machine?
Machine in the annealed or N+T condition with rigid setups, sharp carbide (coated grades) and generous coolant; the 5%Cr matrix work-hardens and is abrasive, so cut speeds roughly 55–60 % of AISI 1212.
Can X12CrMo5 be welded?
Weldable with matching 5Cr-0.5Mo (E502/ER80S-B6) consumables, but requires 200–300 °C preheat/interpass, low-hydrogen practice and PWHT at 700–760 °C to avoid hard martensite and hydrogen cracking.
Can X12CrMo5 be formed, bent or molded?
Hot forge at 1100–1180 °C, finish above 900 °C and cool slowly or normalize; cold forming is limited to gentle bends because of high yield ratio and quench-hardening tendency.
What surface finishes work on X12CrMo5?
Not stainless — protect with phosphating plus high-temperature paint, aluminizing or thermal spray for outdoor/wet service; electroplating requires stress-relief bake to avoid hydrogen embrittlement.
X12CrMo5 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 |
|---|---|---|
| C≤0.15 % per EN 10222-2 / ASTM A182 F5 | 0.08 – 0.15 | 0.12 |
| Si | ≤ 0.5 | 0.3 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | 0.02 |
| S≤0.015 % for high-purity/pressure grades | ≤ 0.02 | 0.01 |
| Cr | 4 – 6 | 5 |
| Mo | 0.45 – 0.65 | 0.55 |
| Niresidual | ≤ 0.3 | 0.15 |
| Fe | balance | — |
X12CrMo5 +I — frequently asked
What is X12CrMo5 +I used for?
X12CrMo5 +I is typically used for valve bodies, flanges and high-temperature fittings. In short: 5 % Cr creep steel; rated to 600 °C; needs preheat and PWHT.
What is the yield strength of X12CrMo5 +I?
X12CrMo5 +I has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 81% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is X12CrMo5 +I easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machine in the annealed or N+T condition with rigid setups, sharp carbide (coated grades) and generous coolant; the 5%Cr matrix work-hardens and is abrasive, so cut speeds roughly 55–60 % of AISI 1212.
Can X12CrMo5 +I be welded?
With care — weldability is rated fair (45/100). Weldable with matching 5Cr-0.5Mo (E502/ER80S-B6) consumables, but requires 200–300 °C preheat/interpass, low-hydrogen practice and PWHT at 700–760 °C to avoid hard martensite and hydrogen cracking.
What surface finishes work on X12CrMo5 +I?
Not stainless — protect with phosphating plus high-temperature paint, aluminizing or thermal spray for outdoor/wet service; electroplating requires stress-relief bake to avoid hydrogen embrittlement.
Can X12CrMo5 +I be formed, bent or molded?
Hot forge at 1100–1180 °C, finish above 900 °C and cool slowly or normalize; cold forming is limited to gentle bends because of high yield ratio and quench-hardening tendency.
What is the maximum service temperature of X12CrMo5 +I?
X12CrMo5 +I 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.
Sources
- EN 10222-2 — Steel forgings for pressure purposes, ferritic and martensitic steels with elevated-temperature properties — CEN (2017)
- EN 10269 — Steels and nickel alloys for fasteners with specified elevated/low temperature properties — CEN (2013)
- ASTM A182/A182M — Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Fittings, Valves and Parts (Grade F5, F5a) — ASTM International (2022)
- GB/T 3077 — (12Cr5Mo) — SAC (2015)
- ASME BPVC Section II Part D — Material Properties (5Cr-1/2Mo) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Mysteel / 1688 (2025)
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.