Heat Resistant & Cr-Mo

E9018-B9 / E9018-B91 Cr-Mo Welding Electrode

E9018-B9, currently classified as E9018-B91, is a low-hydrogen Cr-Mo welding electrode for P91 and T91 Grade 91 steel. It is designed for high-temperature piping, boilers, pressure components and power generation equipment requiring creep-resistant weld metal and controlled post-weld heat treatment.

E9018-B91 Welding Electrode for P91 and T91

E9018-B91 is the current AWS classification for this Grade 91 welding electrode. E9018-B9 is a former or commonly used market designation that may still appear in purchasing specifications and product catalogs.

It is commonly selected for welding:

ASTM A335 P91 pipe

ASTM A213 T91 boiler tube

ASTM A387 Grade 91 plate

ASTM A182 F91 forgings

X10CrMoVNb9-1 and similar Grade 91 steels

For procurement, the electrode classification should match the base material and qualified welding procedure.

Why Choose E9018-B91 for Grade 91 Steel?

P91/T91 steel is a 9Cr-1Mo-V-Nb-N creep-resistant steel developed for elevated-temperature service. Its performance depends on controlled alloy chemistry, welding heat input and post-weld heat treatment.

E9018-B91 provides a compatible weld-metal chemistry for Grade 91 applications, with controlled chromium, molybdenum, vanadium, niobium and nitrogen.

This makes it different from E9018-B3 welding electrode, which is primarily associated with P22/T22 2.25Cr-1Mo steel.

E9018-B91 Chemical Composition

AWS classification requirements for deposited weld metal:

Element	Requirement
C	0.08–0.13%
Mn	≤1.20%
Si	≤0.30%
P	≤0.010%
S	≤0.010%
Ni	≤0.80%
Cr	8.00–10.50%
Mo	0.85–1.20%
V	0.15–0.30%
Nb	0.02–0.10%
N	0.02–0.07%

Actual deposited chemistry depends on the manufacturer and production batch. Project-specific requirements should be verified against the product TDS and MTC.

Mechanical Properties

AWS A5.5 classification minimums:

Property	Minimum
Tensile Strength	≥620 MPa (90 ksi)
Yield Strength	≥530 MPa (77 ksi)
Elongation	≥17%

Actual mechanical properties after PWHT may be higher and should be treated as manufacturer-specific product data.

P91 Welding: Preheat, Interpass and PWHT

P91 welding requires strict control of preheat, interpass temperature, hydrogen, heat input, cooling and PWHT.

Typical commercial guidance includes:

Preheat: approximately 200–300°C

Interpass: controlled according to the qualified WPS

PWHT: commonly around 760°C

Process: SMAW

Polarity: AC or DCEP/DC+

PWHT temperature and holding time depend on the applicable code, material thickness and qualified WPS. Controlled cooling before PWHT may also be required to achieve the intended weld-metal transformation and hardness.

For Grade 91 components, electrode storage and low-hydrogen control are also important to reduce hydrogen-related welding risks.

Typical E9018-B91 Welding Current

Electrode Diameter	Typical Current
2.5 mm	70–110 A
3.2 mm	90–160 A
4.0 mm	130–220 A
5.0 mm	170–250 A

These are typical commercial ranges, not AWS requirements. Final welding parameters should follow the electrode manufacturer's TDS and qualified WPS.

E9018-B91 vs E9018-B3

	E9018-B3	E9018-B91
Base steel	P22 / T22	P91 / T91
Alloy system	2.25Cr-1Mo	9Cr-1Mo-V-Nb-N
Typical service	High-temperature Cr-Mo equipment	Grade 91 creep-resistant equipment
Heat treatment	Important	Highly critical

Do not select B91 or B3 based only on the fact that both are Cr-Mo electrodes. The consumable should be matched to the base steel and qualified welding procedure.

Classification and Industrial Supply

Current AWS classification: E9018-B91

Common/former designation: E9018-B9

AWS: A5.5/A5.5M

ASME: SFA-5.5

EN ISO 3580-A: E CrMo91 B 42 H5, when certified

Welding process: SMAW

Coating: Basic, low-hydrogen

H4 or H4R hydrogen designations should only be stated when supported by the relevant product certification.

GD WELD supplies E9018-B9 / E9018-B91 welding electrodes for P91/T91 piping, boiler components, power plants, pressure equipment and other high-temperature industrial applications.