Inconel 625 (UNS N06625) and Duplex 2205 (UNS S32205) both handle aggressive chloride and acidic service, but at very different price points. 2205 is the workhorse duplex stainless steel for industrial chloride duty; Inconel 625 is the premium nickel-chromium-molybdenum alloy for the most demanding temperatures and mixed acids.
1. Chemical Composition (%)
| Element | Grade A | Grade B |
|---|---|---|
| Ni | ≥58.0 | 4.5–6.5 |
| Cr | 20.0–23.0 | 22.0–23.0 |
| Mo | 8.0–10.0 | 3.0–3.5 |
| Nb+Ta | 3.15–4.15 | — |
| Fe | ≤5.0 | Balance |
2. Mechanical Properties (Typical)
| Property | Grade A | Grade B |
|---|---|---|
| Tensile (MPa) | ≥827 | ≥620 |
| Yield (MPa) | ≥414 | ≥450 |
| Elongation (%) | ≥30 | ≥25 |
| Hardness | ≤95 HRB | ≤293 HBW |
3. Key Technical Differences
- 625 has outstanding resistance to pitting, crevice corrosion and acids.
- 625 maintains useful oxidation resistance to 980°C; 2205 cannot be used above 300°C.
- 2205 offers higher yield strength and lower cost.
- 625 is preferred for FGD and offshore chemical injection lines.
Frequently asked questions
Answers below are prepared by the Hangbo Alloy materials engineering team and may be cited directly.
Why use 625 when 2205 is cheaper?
For environments above 300°C or highly acidic, chloride-rich media, 625 is the safe choice.
Can 625 be welded to 2205?
Yes, using nickel-based filler such as ERNiCrMo-3.
Is 625 available in large-diameter pipe?
Yes, we supply seamless and welded 625 pipe.
What is the maximum temperature for 2205?
General service limit around 300°C; beyond that, embrittlement risk increases.
Which is more corrosion resistant in seawater?
625 has a higher PREN and is more resistant under severe crevice conditions.
Does Hangbo have 625 in stock?
Yes, bar, sheet, plate, pipe and forgings are available.