Manufacturing Process of Inconel 625 Nickel Based Welding Wire

Nickel based welding wire is one of our core product lines, primarily including:

1.Ni‑Cr‑Mo series – e.g., ERNiCrMo‑3 (Inconel 625), offering excellent resistance to pitting and crevice corrosion, making it ideal for harsh marine and chemical environments.

2.Superalloy welding wires – designed for welding Inconel 718, GH series, and other high‑temperature alloys, meeting the demands of aerospace, gas turbine, and high‑temperature strength applications.

3.Ni‑Cr and Ni‑Cu series – e.g., ERNiCr‑3 and ERNiCu‑7 (Monel 400), serving heat‑resistant and reducing‑medium corrosion conditions.

The manufacturing of nickel‑based welding wire follows a closed‑loop process covering melting, hot working, cold drawing, finishing, and packaging.

1.Melting and Forging

The production begins with a two‑step melting process. We employ a duplex technique combining Vacuum Induction Melting (VIM) and Electroslag Remelting (ESR) to effectively control gas content and inclusions, ensuring uniform and precise alloy composition. For premium grades, the ingot density can reach over 99.5%.

During VIM, high‑purity elemental metals are carefully selected as raw materials. The timing and size of alloying additions are precisely controlled to achieve exact composition targets. The process involves a first‑stage high‑temperature, high‑vacuum, long‑duration treatment, followed by a second‑stage low‑temperature thorough stirring, combined with high vacuum and a protective atmosphere, to effectively remove impurities and guarantee stable, high‑purity chemistry.

In the forging stage, the alloy ingots are fully homogenized through annealing to eliminate segregation. Under precisely controlled temperatures, the ingots are forged or hot‑rolled into wire rods. The start‑forging and finish‑forging temperatures are strictly monitored, and all surface defects are thoroughly removed to provide a uniform, defect‑free billet for subsequent wire drawing. A natural‑gas furnace is used for heating. A 1‑ton air hammer is employed in a two‑fire forging sequence: the first fire reduces the ingot to an intermediate size, followed by tempering, and then the final dimensions are achieved. Strict temperature control throughout forging ensures excellent results and lays a solid foundation for the following steps.

2.Rolling and Drawing

During rolling, a 250‑mm bar mill is used. The billet is charged when the furnace reaches 500 °C, then heated to 1050 °C and held for 2.5 hours. Multi‑pass rolling is then carried out, ensuring no folding, fins, or other defects.

After pickling and lubrication, the material undergoes multiple precision cold‑drawing passes. The reduction per pass is scientifically controlled, with intermediate annealing in a protective atmosphere to eliminate work hardening and restore ductility.

The drawing step is performed on a 1.2‑m turntable wire drawing machine using hot drawing. The heating temperature is controlled between 1100 °C and 1150 °C. Through multi‑die drawing (typically 12 passes) combined with intermediate heat treatment, the alloy rod is drawn to the required final dimensions. High‑precision dies and in‑line monitoring ensure that the diameter tolerance is consistently maintained within ±0.02 mm, with a smooth surface finish. Temperature and drawing speed are carefully regulated to guarantee a bright surface free from defects that could affect final product quality.

3.Finished Condition and Packaging

The finished welding wire is subjected to bright treatment or surface cleaning to remove oil and scale. Depending on the grade, solution annealing or other heat treatments are applied to optimize microstructure and properties. After precision straightening, the wire is neatly wound on spools, vacuum‑sealed with desiccant inside to prevent moisture, and clearly labelled for full traceability.

1. Suitable Welding Processes

Nickel‑based welding wire is compatible with a variety of advanced welding methods:

• MIG (Gas Metal Arc Welding) – increases efficiency, particularly suitable for thicker sections.
• TIG (Gas Tungsten Arc Welding) – ideal for precision welding, ensuring aesthetically pleasing and high‑quality welds.
• Submerged Arc Welding – for high‑volume production, used with dedicated fluxes such as INCOFLUX 7 to effectively control weld quality.

2. Weldable Materials

Nickel‑based welding wire can join a wide range of materials. It is primarily used for welding nickel‑base alloys such as Inconel 625, Inconel  825, and Monel400. It excels in dissimilar metal joining, effectively connecting nickel alloys to stainless steels, and can also be used for carbon steels and low‑alloy steels.

3.Welding Precautions

When using nickel‑based welding wires, special attention should be paid to the following:

• Surface cleanliness – the welding area must be thoroughly cleaned of oil, rust, moisture, and other contaminants to ensure weld quality.
• Heat input control – low heat input and low interpass temperatures are recommended to avoid overheating and preserve mechanical properties.
• Shielding gas purity – argon purity must be above 99.99%, with proper flow rates (typically 10‑15 L/min for currents of 100‑200 A).
• Wind protection – adequate shielding against drafts is essential to prevent the shielding gas from being dispersed, which can cause porosity and degrade the weld bead.
• Nozzle and electrode stick‑out – choose the appropriate nozzle size and control the tungsten electrode extension length carefully.

1.Broad Industrial Applications

• Petrochemical industry – used for welding equipment and pipelines handling corrosive media. In strong acid or alkali environments, the weld joints maintain long‑term resistance to chemical attack, ensuring safe and stable production.
• Metallurgical industry – applied in critical components such as high‑temperature furnaces and refining equipment, withstanding high temperatures and complex mechanical stresses to extend service life.
• Nuclear energy sector – employed for welding key components of nuclear reactors, maintaining structural integrity and stability under high radiation and elevated temperatures.

2.Advantages in Specific Conditions

• High‑temperature environments – nickel‑based welding wire exhibits excellent heat resistance, maintaining good mechanical properties at temperatures up to 800 °C. This makes it essential for welding aero‑engine parts, industrial kilns, and other high‑temperature equipment.
• High‑pressure environments – its excellent balance of strength and toughness effectively resists pressure‑induced stresses, ensuring weld reliability.
• Corrosive environments – in marine engineering (seawater corrosion) and chemical plants (strong acid/alkali corrosion), the corrosion resistance of nickel‑based welding wire significantly extends equipment life and reduces maintenance costs.