ER318 is an alloyed stainless steel filler metal containing chromium, nickel, molybdenum, and niobium. Its composition is designed for welding compatible stabilized Cr-Ni-Mo stainless steels.
ER318 Chemical Composition
| Element | Specification (%) | Typical value (%) |
|---|---|---|
| Carbon (C) | ≤0.08 | 0.027 |
| Silicon (Si) | 0.30–0.65 | 0.47 |
| Manganese (Mn) | 1.00–2.50 | 1.55 |
| Sulfur (S) | ≤0.03 | 0.004 |
| Phosphorus (P) | ≤0.03 | 0.025 |
| Nickel (Ni) | 11.00–14.00 | 11.47 |
| Chromium (Cr) | 18.00–20.00 | 18.79 |
| Molybdenum (Mo) | 2.00–3.00 | 2.12 |
| Copper (Cu) | ≤0.75 | 0.29 |
| Niobium (Nb) | 8×C–1.00 | 0.41 |
What Does Chromium Do?
Chromium is the principal alloying element responsible for stainless behavior. In ER318, its specified range is 18.0–20.0%.
Why Is Nickel Included?
Nickel contributes to the austenitic weld-metal structure, ductility, and toughness. ER318 contains 11.0–14.0% nickel.
What Is the Role of Molybdenum?
The 2.0–3.0% molybdenum content supports applications that specify a Mo-bearing stainless weld deposit. Actual corrosion performance still depends on the service environment and welding procedure.
Why Is Niobium Linked to Carbon?
The niobium requirement is calculated in relation to carbon because niobium is added to combine with carbon and stabilize the weld metal. This is an essential distinction between ER318 and low-carbon alternatives such as ER316L.
Why Should Buyers Review Actual Composition?
Two products may carry the same classification while recording slightly different values within the allowed range. Buyers involved in regulated or corrosive-service projects should verify:
- Product classification
- Applicable standard
- Diameter and product form
- Chemical composition
- Mechanical-property requirements
- Traceability requirements
Dayang Welding controls the key alloying elements of ER318 to support consistent supply for matching stainless steel applications.
