444 vs 439
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
444
Stainless Steel
444 is a stabilised, molybdenum-bearing super-ferritic stainless whose pitting resistance rivals 316L while being immune to chloride stress-corrosion cracking. It is widely used for solar and electric water-heater tanks and heat exchangers.
Standards: DIN 1.4521 · AISI 444 · JIS SUS444
439
Stainless Steel
439 is a stabilised 17–19% chromium ferritic stainless with low carbon and nitrogen, giving better formability, weldability and corrosion resistance than 430. It is used for exhaust systems and heat-exchanger tubing as a lower-cost alternative to 304.
Standards: DIN 1.4510 · AISI 439 · GB 06Cr17Ti
Chemical composition compared (%)
| Element | 444 | 439 |
|---|---|---|
| C | ≤0.025 | ≤0.03 |
| Si | ≤1.00 | ≤1.00 |
| Mn | ≤1.00 | ≤1.00 |
| P | ≤0.040 | ≤0.040 |
| S | ≤0.030 | ≤0.030 |
| Cr | 17.50–19.50 | 17.00–19.00 |
| Ni | ≤1.00 | ≤0.50 |
| Mo | 1.75–2.50 | — |
| Ti+Nb | 0.20+4×(C+N)–0.80 | — |
| N | ≤0.035 | ≤0.03 |
| Ti | — | 0.20+4×(C+N)–1.10 |
Properties compared
| Property | 444 | 439 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness | ≤217 HB (annealed) | ≤183 HB (annealed) |
| Tensile strength | 415–640 MPa | 415–585 MPa |
| Density | 7.70 g/cm³ | 7.70 g/cm³ |
| Magnetic | Yes | Yes |
| PREN | ~24 (comparable to 316L) | — |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: 444 · 439. Substitution decisions for certified parts stay with the design authority.