METRODE Welding Rod 20.70.Nb

Core Features "20.70.Nb" Alloy Composition: The "20.70.Nb" designation indicates a nickel-based core with 20% chromium (Cr), 70% nickel (Ni), and niobium (Nb, ~1–2%) additions—matching the composition of heat-resistant 20Cr-70Ni-Nb alloys (e.g., Alloy 617, Haynes 282 variants). This high-Ni matrix delivers exceptional creep resistance (resistance to deformation under long-term heat/load) at ultra-high temperatures (up to 1200°C), while Cr enhances oxidation resistance and Nb stabilizes carbides to prevent grain boundary weakening. Low-Hydrogen Basic Flux Coating: Equipped with a lime-based basic flux coating optimized for DC reverse polarity (DCEP) welding. The coating minimizes hydrogen pickup (≤5mL/100g) to avoid post-weld cracking in thick alloy sections, stabilizes the arc for smooth bead formation, and forms a dense slag layer that shields the weld pool from atmospheric contamination (oxygen, nitrogen). This ensures the weld retains the base alloy’s high-temperature mechanical properties. Ultra-High-Temperature Performance: Engineered for service in extreme high-heat environments (900–1200°C), such as gas turbine components, industrial furnace liners, and aerospace heat exchangers. The 70% Ni content maintains austenitic microstructure at elevated temperatures, while Nb forms strong carbides that resist creep deformation—outperforming standard stainless steel or low-alloy electrodes in long-term high-heat service. All-Position Welding Versatility: Designed for all-position welding (flat, horizontal, vertical-up, overhead) of 20Cr-70Ni-Nb alloys and their dissimilar joints (e.g., to 310 stainless steel). It supports multi-pass welding for thick sections (≥15mm) and produces ductile weld deposits with uniform strength, critical for complex high-temperature component geometries. Oxidation & Corrosion Resistance: The 20% Cr content forms a protective chromium oxide layer on the weld surface, resisting scaling and oxidation in high-heat air or combustion gases. It also offers moderate resistance to mild carburizing and sulfidizing environments, making it suitable for petrochemical and power generation applications. Typical Applications METRODE Welding Rod 20.70.Nb is engineered for ultra-high-temperature, creep-resistant welding of 20Cr-70Ni-Nb nickel-based alloys—ideal for scenarios needing 1200°C service capability, long-term creep resistance, and all-position usability. Key use cases include: Gas Turbine Component Fabrication: Welding 20Cr-70Ni-Nb alloy blades, vanes, or combustion chambers in industrial gas turbines (operating at 1000–1200°C). The Nb-stabilized core resists creep deformation under high rotational loads, while the basic flux ensures crack-free joints—complying with AWS A5.11 standards. High-Temperature Furnace Liners: Repairing or fabricating 20Cr-70Ni-Nb alloy liners for ceramic or metal heat-treating furnaces. The welds resist oxidation and scaling at 900–1100°C, maintaining structural integrity even after prolonged exposure to high heat—complying with ISO 18274 standards. Aerospace Heat Exchangers: Joining 20Cr-70Ni-Nb alloy tubes in aircraft or rocket engine heat exchangers. The alloy’s high-temperature strength handles thermal cycling, and all-position capability suits compact aerospace component designs—complying with EN ISO 14343 standards. Petrochemical Reformer Tubes: Welding 20Cr-70Ni-Nb alloy reformer tubes in hydrogen production plants (exposed to 850–1000°C and hydrogen gas). The Nb addition prevents carbide precipitation, while the flux coating ensures leak-tight joints to avoid hydrogen leakage—complying with ASME BPVC Section IX.