318 Stainless Steel Welding Wire

Chemical composition

• Molybdenum (Mo)： significantly improves resistance to pitting, crevice corrosion and chloride stress corrosion cracking (SCC) in sulfur-containing media such as oil and gas.

• Niobium (Nb)： combines with carbon to form NbC, which inhibits chromium carbide precipitation, prevents intergranular corrosion, and enhances high-temperature stability, and is suitable for environments from 400 to 600℃.

Alloy Details

318 wire optimizes the corrosion resistance and weldability of the weld by increasing the Ni and Mo content and adding Nb:

 

• Nickel content: wire Ni ≥ 11% (base material Ni:6-8%) to ensure the stability of the weld's austenite organization.

 

• Niobium addition: the base material does not contain Nb, the wire through Nb to achieve intergranular corrosion resistance (such as ER318 wire Nb:0.08 ~ 1.0%).

 

• Carbon control: wire C ≤ 0.08% (base material C: 0.22 ~ 0.30%), to reduce the risk of sensitization of the welded heat-affected zone.

 

• Mechanical properties and welding properties

Welding properties
tensile strength	elongation	hardness
≥550MPa	≥30%	≤24HRC

 

• Corrosive environment selection:

- High hydrogen sulfide environment: Prefer ER318 wire (with Nb) to inhibit hydrogen embrittlement and sulfide stress cracking.

- High temperature environment: ER318Si wire improves fluidity by adding silicon, suitable for complex weld molding.

Application

• Petrochemical equipment welding

Hydrogen sulfide corrosion-resistant environments: for welding of oil and gas extraction equipment containing H₂S gas, such as wellhead devices, valves, valve stems and fasteners, especially in the harsh environment where the partial pressure of H₂S is more than 1MPa.

Chemical vessels and pipelines: used for sulfuric acid, nitric acid production equipment and storage and transportation equipment welding (such as SUS316Ti/Nb material), resistant to strong acid medium corrosion.

• Offshore Engineering and Shipbuilding

Seawater corrosion protection: welding of ship fittings, offshore platform structures and desalination equipment, resistance to pitting and stress corrosion cracking caused by seawater chloride ions.

High salt spray environment: applicable to the maintenance and reinforcement of metal parts of offshore drilling platforms to extend service life.

• Food and Pharmaceutical Industry

Sanitary Equipment Welding: Used for welding of food processing containers, conveying pipelines and pharmaceutical equipment, its low impurity content and corrosion resistance meet the sanitary standards.

High-temperature sterilization environment: withstanding 400℃ high temperature, it is suitable for welding of medical equipment that requires frequent high-temperature sterilization.