Durehete 1055 Welding Wire (Alloy T41 / EN 10269 20CrMoVTiB4-10): Matching Cr-Mo-V-Ti-B Filler for Steam Turbine Bolt Repair

The wire is bought in three situations: HP turbine bolt thread repair where the bolt body is recoverable and a new bolt is not on the shelf; casing weld-buildup where corrosion or erosion has thinned a flange face below the design envelope; and stress-relief field welding of attachment lugs on Durehete 1055 parent material. The procedure is hot, slow and conservative: pre-heat 200°C minimum, interpass capped below 300°C, hydrogen-bake the electrode at 350°C for 2 hours, immediate post-weld dehydrogenation hold at 250°C for 2 hours, then PWHT at 690°C for 4 hours minimum. Welding procedure qualification to ASME Section IX is mandatory before the wire goes to the shop floor; the WPS is held a fixed margin below the original temper temperature so bulk hardness and creep properties are not eroded.

Available Diameters (1.0 to 4.0 mm TIG/MIG Wire, 2.5 to 5.0 mm SMAW Electrode)

The wire is rolled in the diameter set the field crews use, in spool or rod form by welding process. Solid wire on 15 kg spools is the default for TIG and MIG; SMAW rods are supplied in 5 kg cardboard cartons with a foil-sealed inner pack to control moisture. Each carton carries the heat number and the moisture-control instruction (re-bake at 350°C for 2 hours before use, hold in heated quiver at 120°C during shift).

Process	Diameter Range	Standard Steps	Pack Form	Typical Application
TIG (GTAW)	1.0 to 3.2 mm	0.2 mm	1 m straight rod, 5 kg tin	Root pass on bolt thread repair, attachment weld
MIG (GMAW)	1.0 to 1.6 mm	0.2 mm	15 kg spool	Fill pass on casing buildup
Submerged arc (SAW)	2.4 to 4.0 mm	0.4 mm	25 kg coil	Long-pass casing buildup with flux
SMAW electrode	2.5 to 5.0 mm	0.5 mm	5 kg carton, foil-sealed	Field repair, thread buildup, lug weld

Composition Matching Base Metal Cr-Mo-V-Ti-B Chemistry

The deposit chemistry targets the parent-metal envelope of Durehete 1055: 1Cr-1Mo-0.75V backbone with the 0.04 to 0.10 Ti and 0.005 to 0.010 B microalloying that defines the creep-rupture line. Sulfur and phosphorus are held at the lower bound of the EN 10269 20CrMoVTiB4-10 / 1.7729 envelope so the deposit is hot-crack resistant. Hydrogen on the as-supplied rod is held below 5 mL per 100 g of weld metal (H5 class) by storage and bake procedure. Diffusible hydrogen at the weld pool below 4 mL per 100 g.

Element	Wire Deposit (target)	Base Metal (Durehete 1055)	matched-composition filler per manufacturer welding-procedure datasheet (typical)
Carbon (C)	0.08 to 0.12	0.20 to 0.25	0.07 to 0.12
Manganese (Mn)	0.60 to 0.90	0.45 to 0.70	0.60 to 1.20
Silicon (Si)	0.20 to 0.40	0.10 to 0.35	0.30 to 0.80
Chromium (Cr)	1.00 to 1.50	1.00 to 1.50	0.30 to 1.50
Molybdenum (Mo)	0.85 to 1.25	0.85 to 1.25	0.45 to 1.10
Vanadium (V)	0.40 to 0.70	0.60 to 0.75	0.00 to 0.15
Titanium (Ti)	0.04 to 0.10	0.04 to 0.10	not specified
Boron (B)	0.003 to 0.008	0.005 to 0.010	not specified
Sulfur, max (S)	0.015	0.025	0.030
Phosphorus, max (P)	0.015	0.025	0.030
Diffusible hydrogen	4 mL / 100 g max	n/a	5 mL / 100 g (H5)

Welding Procedure (Pre-Heat 200°C, Interpass below 300°C, PWHT 690°C for 4 h)

The procedure for Durehete 1055 wire on matching parent metal is hot, hydrogen-controlled and slow-cooled. Each step is non-negotiable: skipping pre-heat, holding too high an interpass temperature or omitting the dehydrogenation soak produces hydrogen-induced cracking in the heat-affected zone within 24 to 48 hours of weld completion. The PWHT temperature is held at least 30°C below the original temper of the parent so bulk hardness and creep-rupture properties stay intact.

• Pre-heat: 200°C minimum on the parent metal at 75 mm either side of the weld joint, measured by surface thermocouple. Pre-heat held throughout welding.
• Electrode bake: SMAW rods baked at 350°C for 2 hours and held in heated quiver at 120°C during shift. Open carton consumed within 4 hours.
• Welding process: GTAW preferred for root pass, SMAW or GMAW for fill, SAW for long casing-buildup runs.
• Interpass temperature: hold at 200 to 300°C. Above 300°C, stop and wait for cool-down.
• Dehydrogenation hold: immediately after final pass, hold at 250°C for 2 hours minimum before air cool. Skipping this step is the #1 cause of HIC failure.
• PWHT: 690°C for 4 hours minimum, slow-cool below 300°C in furnace. Repair contracts call for 6 to 8 hours on heavy section.
• NDT after PWHT: 100 percent magnetic-particle, ultrasonic per BS EN ISO 17640 acceptance level 2, hardness survey HAZ less than 350 HV10 per NACE MR0175.

Applications — HP Turbine Bolt Buildup, Thread Repair, Stress-Relief Welding

The wire is consumed by maintenance contractors on running power plant during turnaround windows where new-build bolt procurement is too slow. The three highest-volume applications:

• HP turbine bolt thread repair: galled or stripped threads on European OEM steam turbines and US OEM steam turbines casing studs. The bolt body is reclaimed by build-up welding the thread profile and re-cutting; PWHT applied to the entire bolt.
• HP casing flange buildup: corrosion or erosion has thinned a flange face below the gasket-seating envelope. Layered weld buildup restores the face; ground to flatness; PWHT applied.
• Stress-relief field welding: attachment of monitoring lugs, instrument bosses or platform brackets on Durehete 1055 casing parent metal. Procedure-qualified to ASME Section IX.
• Rotor disc repair: qualified repair of rotor disc Cr-Mo-V welds where the OEM has authorised a weld repair under the residual-life assessment programme.
• Bolt seat machining recovery: casing bolt-circle counterbores that have lost flatness over time can be built up and re-machined without removing the casing from the train.

End-users include European steam-turbine OEMs SST-series, GE Power 7H-series, Japanese OEM steam turbines, European steam-turbine programmes, Toshiba, Italian steam-turbine programmes and BHEL repair contracts. The wire is procured against the project welding-procedure specification (WPS) and the wire MTC is held by the welding engineer at the site.

AWS Classification (A5.5 Low-Alloy Steel Electrode, Manufacturer-Declared Chemistry)

The AWS classification system covers the Cr-Mo-V family under A5.5 (low-alloy steel electrodes for SMAW) with the G-suffix general grade being the closest off-the-shelf carton. The G-suffix is the "general" alloy class and the manufacturer declares the chemistry on the carton certificate. There is no AWS letter-grade that explicitly carries the Ti+B microalloying; the wire is supplied as a custom modification of the A5.5 G-suffix grade with the deposit chemistry declared on the EN 10204 type 3.1 certificate. Solid wire for TIG and MIG falls under AWS A5.28 ER90S-G with the same caveat: the G-suffix is the general class and the deposit chemistry is the differentiator. Sub-arc wire and flux fall under AWS A5.23 F9P-EG-G.

Form	AWS Class	EN Class	Deposit Strength
SMAW electrode	A5.5 low-alloy steel electrode, manufacturer-declared chemistry	EN ISO 3580-A E CrMoV1 B 42 H5	620 MPa tensile min
Solid wire TIG/MIG	A5.28 ER90S-G	EN ISO 21952-A W CrMoV1Ti	620 MPa tensile min
SAW wire and flux	A5.23 F9P-EG-G	EN ISO 24598-A S CrMoV1	620 MPa tensile min

Frequently Asked Questions on Durehete 1055 Welding Wire

What is the matching filler for Durehete 1055 base metal?

The matching filler is a Cr-Mo-V-Ti-B solid wire (TIG/MIG) or low-hydrogen SMAW rod with chemistry inside the deposit envelope of 1.0 to 1.5 Cr, 0.85 to 1.25 Mo, 0.40 to 0.70 V, 0.04 to 0.10 Ti, 0.003 to 0.008 B. The closest AWS classification is A5.5 low-alloy steel electrode, manufacturer-declared chemistry (SMAW) or A5.28 ER90S-G (TIG/MIG) with the alloy modification declared on the certificate.

What pre-heat and PWHT are required?

Pre-heat 200°C minimum on the parent metal at 75 mm either side of the joint, held throughout welding. Interpass capped at 300°C. Immediate post-weld dehydrogenation hold at 250°C for 2 hours. PWHT at 690°C for 4 hours minimum, slow-cool below 300°C in furnace. Skipping any step risks HIC in the HAZ within 24 to 48 hours.

What hydrogen control is required?

H5 class (diffusible hydrogen below 5 mL per 100 g of weld metal). SMAW rods baked at 350°C for 2 hours and held in a heated quiver at 120°C during the shift; open carton consumed within 4 hours. Solid wire stored in sealed packaging; spools opened on the shop floor on the day of use. Joint pre-cleaning removes oil, grease and moisture to the same standard as nuclear bolting weld-repair.

What MTC and certifications come with the wire?

EN 10204 type 3.1 by default and type 3.2 on request. Heat number, full chemistry on the deposit, all-weld-metal tensile at room temperature and 540°C, Charpy V at 20°C on the deposit, diffusible hydrogen to ISO 3690, hardness on the weld and HAZ. Manufacturer's certificate to AWS A5.5 plus the alloy modification declaration. WPS qualification to ASME Section IX held by the project welding engineer.

What is the standard lead time and packing?

SMAW rod 2.5 to 5.0 mm: 6 to 8 weeks from confirmed PO. TIG/MIG wire 1.0 to 4.0 mm: 8 to 10 weeks against project tonnage. Packing: SMAW rods in 5 kg foil-sealed cartons inside 25 kg wood crate; solid wire on 15 kg spool inside vacuum bag inside cardboard carton. Heat number, AWS class and bake-instruction label on every carton. Marine-export packing on call-out.