Alloy 20 / Carpenter 20 vs 904L / X1NiCrMoCu25-20-5: Both austenitic for acid environments — different acid specializations
Alloy 20 / Carpenter 20 vs 904L / X1NiCrMoCu25-20-5
Side-by-side chemical composition and mechanical property comparison.
Overview
Alloy 20 / Carpenter 20
2.4660
Austenitic Ni-Fe-Cr alloy specifically developed for sulfuric acid resistance. Nb-stabilized against sensitization. Cu addition gives outstanding resistance to H2SO4 at all concentrations up to 80%. Used for sulfuric acid piping, heat exchangers, mixing tanks, pickling equipment, and pharmaceutical processing.
904L / X1NiCrMoCu25-20-5
1.4539
Super-austenitic stainless steel with high Mo and Cu content. Excellent resistance to sulfuric acid, phosphoric acid, and chloride environments. Bridges the gap between standard austenitics (316L) and nickel alloys (Inconel/Hastelloy). Used in chemical processing, oil & gas, and pharmaceutical.
| Alloy 20 / Carpenter 20 | 904L / X1NiCrMoCu25-20-5 | |
|---|---|---|
| Material Number | 2.4660 | 1.4539 |
| Category | Nickel Alloys | Stainless Steel |
| Standard | ASTM B463 | EN 10088-2 |
Chemical composition (wt%)
| Element | Alloy 20 / Carpenter 20 | 904L / X1NiCrMoCu25-20-5 | Overlap |
|---|---|---|---|
| C | 0–0.07% | 0–0.02% | OK |
| Si | 0–1% | 0–0.7% | OK |
| Mn | 0–2% | 0–2% | OK |
| P | 0–0.035% | 0–0.03% | OK |
Mechanical properties
| Property | Alloy 20 / Carpenter 20 | 904L / X1NiCrMoCu25-20-5 | Unit |
|---|---|---|---|
| tensile_strength | ≥ 551 | 490–690 | MPa |
| yield_strength | ≥ 241 | ≥ 220 | MPa |
| elongation | ≥ 30 | ≥ 35 | % |
Compatibility Assessment
Alloy 20 has Cu (3-4%) optimized for sulfuric acid. 904L has higher Mo (4-5%) for better chloride pitting resistance. Both are Nb-stabilized. Choose Alloy 20 for H2SO4 service; 904L for mixed chloride+acid environments.
Frequently Asked Questions
Is Alloy 20 / Carpenter 20 the same as 904L / X1NiCrMoCu25-20-5?
Alloy 20 / Carpenter 20 and 904L / X1NiCrMoCu25-20-5 have a 60% composition overlap. Both austenitic for acid environments — different acid specializations
Can I replace Alloy 20 / Carpenter 20 with 904L / X1NiCrMoCu25-20-5?
Generally not recommended. The compositions differ significantly (60% overlap). These materials have different alloying concepts and are intended for different applications.
What is the difference between Alloy 20 / Carpenter 20 and 904L / X1NiCrMoCu25-20-5?
The main differences are in the following elements: Mo, Ni, Cu. Alloy 20 / Carpenter 20 is a Nickel Alloys grade, while 904L / X1NiCrMoCu25-20-5 is a Stainless Steel grade.
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