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Durehete 1055 (EN 10269 / Alloy T41 / Werkstoff 1.7729 / 20CrMoVTiB4-10) Cr-Mo-V-Ti-B High-Temperature Bolting Steel
Durehete 1055 is the top grade of the Durehete family of Cr-Mo-V-Ti-B creep-resistant bolting steels. The grade has a stable cross-reference chain: Durehete 1055 = Alloy T41 = Werkstoff 1.7729 = EN designation 20CrMoVTiB4-10 = Polish PN 20HMFTB. The primary controlling specification is EN 10269 (steels and nickel alloys for fasteners with specified elevated-temperature and/or low-temperature properties). The Durehete name encodes the maximum design temperature: 1055°F (approximately 568°C). Current bar producer: Tata Steel UK (formerly Corus Products USA).
Durehete 1055 is supplied by TorqBolt as custom-machined high-temperature bolts, stud bolts, hex bolts, heavy hex bolts, tap studs, weld studs, body-bound studs, couplings, U-bolts, fasteners, round bar and forging stock. In the quenched-and-tempered condition tensile strength is 820 to 1000 MPa with a minimum 0.2 percent proof stress of 660 MPa. EN 10269 Annex A provides the elevated-temperature design-stress data used in the procurement inquiry.
Durehete 1055 Characteristics and Key Properties
Durehete 1055 / Alloy T41 is the top grade of the Durehete creep-resistant bolting family. Its Cr-Mo-V backbone (Cr 0.9 to 1.2 percent, Mo 0.9 to 1.1 percent, V 0.6 to 0.8 percent) is the alloy spine; the verified microalloying additions are titanium 0.07 to 0.15 percent and boron 0.02 percent max per the producer datasheets. Microstructure after the Q+T cycle is tempered bainite. Sister grades Durehete 950 (Alloy T31 / 1.7711 / 40CrMoV4-6) and Durehete 900 (Alloy T22 / 42CrMoV5-6) sit one and two steps below 1055 on the family service-temperature ladder, as documented in EN 10269 Annex As SA-145 (Durehete 950) and SA-138 (Durehete 900).
Durehete 1055 Chemical Composition (EN 10269 / 20CrMoVTiB4-10 / Werkstoff 1.7729)
Element ranges for Durehete 1055 / Alloy T41 / 20CrMoVTiB4-10 / Werkstoff 1.7729, compiled. The dedicated chemical composition page carries the same data with additional notes.
| Element | Durehete 1055 (wt%, verified) | Source |
|---|---|---|
| Carbon (C) | 0.17 to 0.23 | EN 10269 spec |
| Silicon (Si) | 0.40 max | EN 10269 spec |
| Manganese (Mn) | 0.35 to 0.75 | EN 10269 spec |
| Nickel (Ni) | 0.20 max | EN 10269 spec |
| Chromium (Cr) | 0.90 to 1.20 | EN 10269 spec |
| Molybdenum (Mo) | 0.90 to 1.10 | EN 10269 spec |
| Vanadium (V) | 0.60 to 0.80 | EN 10269 spec |
| Titanium (Ti) | 0.07 to 0.15 | EN 10269 spec |
| Aluminium (Al) | 0.20 max | EN 10269 spec |
| Boron (B) | 0.02 max | EN 10269 spec |
Durehete 1055 Mechanical Properties (Quenched and Tempered)
Room-temperature values for Durehete 1055 / Alloy T41 in the quenched-and-tempered condition. Elevated-temperature design data follows EN 10269 Annex A.
| Property | Value (Q+T) | Test Standard |
|---|---|---|
| Tensile strength (Rm) | 820 to 1000 MPa | BS EN ISO 6892-1 |
| 0.2 percent proof stress (Rp0.2, min) | 660 MPa | BS EN ISO 6892-1 |
| Condition | Quenched and tempered | To EN 10269 |
Durehete 1055 Heat Treatment (Austenitize, Oil or Water Quench, Temper)
Durehete 1055 / Alloy T41 heat-treatment cycle: austenitize at 970 to 1010°C, oil or water quench, temper at 660 to 730°C for not less than 2 hours and air cool. The tempering temperature is selected by the mill to balance yield strength and creep-rupture life for the specific bar diameter and the EN 10269 inquiry that the lot is being produced against.
Durehete 1055 Welding Notes
Bolting in Durehete 1055 is supplied in the quenched-and-tempered condition and is not field-welded; the alloy is procured as a finished fastener. Where repair-weld qualifications are required for rotors or casings, procedure development should follow the producer datasheet and the project EN 10269 Annex A inquiry; specific consumable selection and PWHT cycles are agreed between the buyer, the welding contractor and the producer for each repair. Refer to the welding page for procedure-development notes.
Durehete 1055 Standards Cross-Reference (EN 10269 Anchored)
The primary controlling standard for Durehete 1055 is EN 10269. The table below lists the documented designations.
| Designation | Body | Notes |
|---|---|---|
| EN 10269 | European harmonised | Primary specification (steels and nickel alloys for fasteners with specified elevated-temperature and/or low-temperature properties) |
| 20CrMoVTiB4-10 | EN 10269 | EN designation for Durehete 1055 |
| 1.7729 | Werkstoff | Werkstoff number for Durehete 1055 |
| Alloy T41 / T41 | Trade alias | Trade aliases per producer datasheets |
| 20HMFTB | Polish PN | Polish PN designation |
Durehete 1055 Applications (per Producer Datasheets)
Typical applications listed by the EN 10269 specification:
- Turbine fasteners for European and UK power-generation OEMs and EPC contractors
- Boiler support rods and fasteners at elevated service temperature
- Power generation bolting under EN 10269 inquiry
- General process plant elevated-temperature bolted joints
Durehete 1055 vs Durehete 950 vs Durehete 900
Within the family, the three Durehete grades are graded by maximum service temperature, encoded in the °F number that gives each grade its name. EN 10269 is the primary specification for all three.
| Grade | EN designation | Werkstoff | Trade alias | US alias (where documented) |
|---|---|---|---|---|
| Durehete 1055 | 20CrMoVTiB4-10 | 1.7729 | Alloy T41 / T41 | n/a |
| Durehete 950 | 40CrMoV4-6 | 1.7711 | Alloy T31 | ASTM A193 B16 (ASM SA-145) |
| Durehete 900 | 42CrMoV5-6 | Alloy T22 | n/a |
Durehete 1055 Forms and Fasteners
Durehete 1055 is a bolting steel. TorqBolt supplies it as custom-machined bolts and stud bolts produced from forged bar stock through the full Q+T heat-treatment cycle to EN 10269. Mill test certificate (EN 10204 type 3.1 by default, type 3.2 on request) and third-party witness inspection are available on call-out.
| Form Category | Products |
|---|---|
| Bar and forging stock | Round bar to EN 10269, forging stock for in-house bolt-making |
| High-temperature bolting | Bolts, hex bolts, heavy hex bolts, stud bolts, tap studs, weld studs, body-bound studs |
| Specialised fasteners | Couplings, U-bolts, threaded rod, nuts, washers, anchor bolts |
Durehete 1055 Frequently Asked Questions
What is Durehete 1055?
Durehete 1055 is a Cr-Mo-V-Ti-B creep-resistant alloy steel for high-temperature bolting under EN 10269. It is also known as Alloy T41, T41, Werkstoff 1.7729, EN designation 20CrMoVTiB4-10 and Polish PN 20HMFTB. The grade name encodes the maximum design temperature: 1055°F (approximately 568°C).
What is the EN designation for Durehete 1055?
20CrMoVTiB4-10,. The corresponding Werkstoff number is 1.7729.
Is there a documented US bolting equivalent to Durehete 1055?
No published US correlation exists for Durehete 1055 itself. Within the family, EN 10269 Annex A documents ASTM A193 B16 as the US equivalent of Durehete 950 (Alloy T31 / 40CrMoV4-6). Durehete 1055 / Alloy T41 is procured directly under its EN 10269 designation.
What are the mechanical properties of Durehete 1055?
In the quenched-and-tempered condition, tensile strength is 820 to 1000 MPa with a minimum 0.2 percent proof stress of 660 MPa. Values per the EN 10269 specification.
What is the heat treatment for Durehete 1055?
Austenitize at 970 to 1010°C, oil or water quench, temper at 660 to 730°C for not less than 2 hours and air cool. Values per the EN 10269 specification.
What MTC do you supply with Durehete 1055 bolting?
EN 10204 type 3.1 by default and type 3.2 on request. Heat number, full chemistry to EN 10269, mechanical test results, full Q+T heat-treatment chart (austenitize, quench and temper temperatures and dwell times) and dimensional report tied to the heat lot. Third-party witness inspection (LR, DNV, BV, SGS, TUV) is available on call-out.
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