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Durehete 1055, 950 & 900 — Cr-Mo-V-Ti-B High-Temperature Bolting Steels (Alloy T41 / T31 / T22, EN 10269 / Werkstoff 1.7729 / 1.7711 / 42CrMoV5-6)
Durehete 1055 (with sister grades Durehete 950 and Durehete 900) is a Cr-Mo-V-Ti-B creep-resistant alloy steel for high-temperature bolting. The three grades are covered by EN 10269 (steels and nickel alloys for fasteners with specified elevated-temperature and/or low-temperature properties). The Durehete name derives from the maximum design temperature in degrees Fahrenheit (1055°F ≈ 568°C for the top grade). Each grade has a stable trade-alias chain: Durehete 1055 = Alloy T41 = Werkstoff 1.7729 = EN designation 20CrMoVTiB4-10 = Polish PN 20HMFTB; Durehete 950 = Alloy T31 = Werkstoff 1.7711 = 40CrMoV4-6 = ASTM A193 B16; Durehete 900 = Alloy T22 = 42CrMoV5-6. The producer of the bar-stock pedigree is Tata Steel UK (formerly Corus Products USA).
Durehete 1055 / 950 / 900 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. For Durehete 1055 in the quenched-and-tempered condition, room-temperature tensile is 820 to 1000 MPa with a minimum 0.2 percent proof stress of 660 MPa (per published EN 10269 specification). Procurement is typically by specification call-out under EN 10269 for European and UK power-generation, process-plant and turbine-fastener applications.
Durehete 1055 Characteristics and Key Properties
Durehete 1055 is engineered for creep-resistant bolting at elevated temperature under EN 10269. The 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) gives carbide stability; the controlled titanium (0.07 to 0.15 percent) and boron (0.02 percent max) additions are the defining feature versus a plain Cr-Mo-V. The grade name encodes the maximum design temperature: 1055°F (approximately 568°C). Durehete 950 (Alloy T31) and Durehete 900 (Alloy T22) sit one step and two steps below 1055 on the family creep-strength ladder. Microstructure after Q+T is tempered bainite. Typical applications listed by primary producer datasheets include turbine fasteners, boiler support rods and fasteners, power generation and general process plant.
Durehete 1055 / 950 / 900 Trade Names and International Equivalents
Each Durehete grade has a stable cross-reference chain across European, UK and US bolting standards. The primary controlling standard is EN 10269. Designations below are sourced. The current producer of the bar pedigree is Tata Steel UK (formerly Corus Products USA).
| Durehete grade | Trade alias | Werkstoff | EN designation | Other |
|---|---|---|---|---|
| Durehete 1055 | Alloy T41 | 1.7729 | 20CrMoVTiB4-10 (EN 10269) | Polish PN 20HMFTB |
| Durehete 950 | Alloy T31 | 1.7711 | 40CrMoV4-6 (EN 10269) | ASTM A193 B16 |
| Durehete 900 | Alloy T22 | 42CrMoV5-6 | EN 10269 | |
| EN 10269 | European harmonised standard for steels and nickel alloys for fasteners with specified elevated-temperature and/or low-temperature properties (primary controlling specification for all three Durehete grades) | |||
Durehete 1055 Chemical Composition (EN 10269 / 20CrMoVTiB4-10 / 1.7729)
Element ranges for Durehete 1055 = Alloy T41 = 20CrMoVTiB4-10 = Werkstoff 1.7729 compiled. Element-by-element ranges are listed below; the dedicated chemical composition page carries the same data with additional notes on melt-shop practice.
| 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 Condition)
Room-temperature mechanical values for Durehete 1055 / Alloy T41 in the quenched-and-tempered condition. Elevated-temperature design data is published in 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 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 cycle delivers the tempered microstructure responsible for the room-temperature 660 MPa minimum yield. The tempering temperature is the principal lever for balancing yield strength against creep-rupture life and is selected by the mill based on the diameter and the service condition that the EN 10269 inquiry calls for.
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, not a weld-fabricated joint. 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 not generally published as a single one-size cycle and are agreed between the buyer, the welding contractor and the producer for each repair. Refer to the welding page for procedure-development notes.
Durehete Standards Cross-Reference (EN 10269 Anchored) (EN 10269 Anchored)
The primary controlling standard for all three Durehete grades is EN 10269. The table below maps the Durehete trade name to the EN designation, the Werkstoff number and the documented US bolting alias where a published correlation exists in EN 10269.
| Durehete grade | EN 10269 designation | Werkstoff | US alias (where documented) | Source |
|---|---|---|---|---|
| Durehete 1055 (Alloy T41) | 20CrMoVTiB4-10 | 1.7729 | n/a | EN 10269 spec |
| Durehete 950 (Alloy T31) | 40CrMoV4-6 | 1.7711 | ASTM A193 B16 | EN 10269 |
| Durehete 900 (Alloy T22) | 42CrMoV5-6 | EN 10269 | ||
| EN 10269 | Primary specification: steels and nickel alloys for fasteners with specified elevated-temperature and/or low-temperature properties | |||
Durehete 1055 vs 950 vs 900 (EN 10269 Family)
Within the Durehete family the three 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. Only the verified comparisons appear in the table below.
| Grade | EN designation | Werkstoff | Trade alias | US alias (where documented) |
|---|---|---|---|---|
| Durehete 1055 | 20CrMoVTiB4-10 | 1.7729 | Alloy T41 | n/a |
| Durehete 950 | 40CrMoV4-6 | 1.7711 | Alloy T31 | ASTM A193 B16 (EN 10269) |
| Durehete 900 | 42CrMoV5-6 | Alloy T22 | n/a |
Durehete 1055 Applications (per Producer Datasheets)
Applications under EN 10269 service envelope for Durehete 1055:
- 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 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. It is the top grade of the Durehete family and is also known as Alloy T41 and Werkstoff 1.7729. Its EN designation under EN 10269 is 20CrMoVTiB4-10; the Polish PN designation is 20HMFTB. The name encodes the maximum design temperature: 1055°F (approximately 568°C).
What is the difference between Durehete 1055, 950 and 900?
The three Durehete grades sit on a stepped service-temperature ladder. Durehete 1055 = Alloy T41 = 20CrMoVTiB4-10 (1.7729) is the top grade. Durehete 950 = Alloy T31 = 40CrMoV4-6 (1.7711) is the middle grade and has a documented US alias of ASTM A193 B16. Durehete 900 = Alloy T22 = 42CrMoV5-6 is the lowest of the three. All three are covered by EN 10269.
What is the primary standard for Durehete?
EN 10269 is the primary controlling standard for Durehete 1055, 950 and 900. EN 10269 is the European harmonised standard for steels and nickel alloys for fasteners with specified elevated-temperature and/or low-temperature properties.
Is there a documented US bolting equivalent to Durehete?
Yes, but only for Durehete 950. EN 10269 documents ASTM A193 B16 as the US equivalent of Durehete 950 / Alloy T31 / 40CrMoV4-6. No equivalent ASTM correlation is published in EN 10269 for Durehete 1055 or 900, so those two grades are procured directly to EN 10269.
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. The tempering temperature is the principal lever for balancing yield strength against creep-rupture life.
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 applications use Durehete 1055?
Applications under the EN 10269 service envelope are turbine fasteners, boiler support rods and fasteners, power-generation bolting and general process-plant elevated-temperature fasteners.
What MTC do you supply with Durehete 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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