Welding Wire
ER90S-B9
ER90S-B9 is a V-Nb strengthened 9Cr-1Mo martensitic welding wire to AWS A5.28, for MIG/TIG welding of P91/T91/F91 steel up to 600~650℃.
WELDING WIRE AND ROD (MIG & TIG)
ER90S-B9 is a V-Nb strengthened 9Cr-1Mo martensitic welding wire to AWS A5.28, for MIG/TIG welding of P91/T91/F91 steel up to 600~650℃.
Applicable Welding Processes & Shielding Gases
1, MIG GMAW (spool wire for fill & cap passes)
· Preferred shielding gas: 90% Ar + 10% CO₂ / 98% Ar + 2% O₂
· Gas flow rate: 18~22 L/min
· Polarity: DCEP
2, TIG GTAW (TIG rod for root passes)
· Shielding gas: 100% high-purity argon (≥99.99%)
· Gas flow rate: 10~15 L/min; back purging is required for pipe root welds
· Polarity: DCEN
Welding Positions for MIG & TIG
Both MIG and TIG support all-position welding (flat, horizontal, vertical, overhead)
· TIG: Precise molten pool control with consistent bead appearance, first choice for overhead pipe root welding.
· MIG: Optimal performance on flat & horizontal positions; pulse MIG is recommended for vertical and overhead welding to prevent weld sagging.
Mechanical Properties
(Minimum AWS Requirements, PWHT at 750℃ for 2 Hours)
· Tensile Strength: ≥620 MPa (90 ksi) 0.2% Offset
· Yield Strength: ≥410 MPa (60 ksi)
· Elongation: ≥16%
· Charpy V-notch Impact Energy: ≥27 J at ambient temperature.
Core advantages: excellent high-temperature creep resistance & steam oxidation resistance at 600~650℃.
Features
· Copper-coated MIG wire for smooth feeding; copper-free TIG rod avoids high-temperature copper embrittlement for critical projects,
· Low spatter, smooth weld beads, compliant with Class 1 RT & ASME pressure vessel standards,
· V-Nb alloy delivers better creep strength than ER80S-B2 for supercritical power plants,
· High hardenability requires mandatory preheat, interpass temperature control and PWHT,
· All-position weldable; TIG is ideal for overhead pipe root passes,
· Low X-factor formula resists temper embrittlement under long-term high-temperature & hydrogen service.
Base Metals for Welding
· Applicable Base Metals Power piping steel: A335 P91, A213 T91
· Plates & forgings: A387 Gr91, A182 F91
· Modified 9Cr martensitic steel for supercritical boiler headers, turbine valves and high-temperature hydrogenation piping.
Welding Precautions
·Preheat workpieces ≥6mm to 200~250℃, higher in cold weather,
·Keep interpass temperature 200~300℃ during welding,
·Mandatory PWHT: hold at 730~760℃ for 2~4h with slow cooling,
·Clean rust, oil and moisture on groove surfaces,
·Use back argon shielding for pipe root welds,
·Wind protection required for outdoor welding,
·Store wire dry; do not use damp welding wire.
Common Technical Issues & Solutions
·Cold & delayed cracks Keep proper preheat/interpass temperature, clean grooves and perform PWHT.
·Root oxidation & RT defects Use back argon purge for pipes; grind oxide between layers.
·Molten pool sagging (vertical/overhead) Adopt pulse MIG with low current & short arc.
·Alloy oxidation & poor high-temperature performance Set wind barriers and use standard mixed shielding gas.
·Weld pores Check gas lines, dry wire and remove moisture on workpieces.
·Temper embrittlement Use low X-factor wire and follow standard PWHT process.
·Wrong matching steel Only for P91/T91/F91; cannot replace ER80S-B2.
