- Grade / Alloy
- 446
- EN / W.Nr.
- 1.4749X18CrN28
- AISI / SAE
- 446
- UNS
- S44600
- Family
- Ferritic
Chemical composition
Chemical composition
Composition limitsComposition limits for heat-resisting steels within EN 10095.
| Element | Content (% by mass) |
|---|---|
| CCarbon | 0.15–0.2 |
| SiSilicon | ≤ 1 |
| MnManganese | ≤ 1 |
| PPhosphorus | ≤ 0.04 |
| SSulfur | ≤ 0.015 |
| CrChromium | 26–29 |
| NNitrogen | 0.15–0.25 |
Values describe the grade, not the analysis of a specific batch. The applicable product specification and material certificate determine acceptance. A dash does not mean zero.
What is 446 / 1.4749?
1.4749 is a heat-resistant ferritic stainless steel known for its high chromium content. It is also identified as 446 and UNS S44600. Its EN chemical designation is X18CrN28; X15CrN26 can appear in other standards tables. This difference in naming does not make other high-chromium steels, such as 1.4762, the same material. The characteristic role of 446 is in industrial equipment exposed to hot gases rather than general-purpose room-temperature service.
Sulfur-bearing hot gases and heat recovery
Heat-recovery equipment in the metals and glass industries reuses energy from hot gases. In these environments, the substances in the gas influence the metal surface as well as the temperature itself. Resistance to sulfur-bearing gases and high-temperature oxidation is a recognised characteristic of 446. Applications include recuperators, protective tubes exposed to hot gases and certain injection components. A heavily loaded element and a protective section within the same furnace can therefore have different material duties.
How it differs from austenitic grades such as 310S
446 is ferritic, whereas 310S is austenitic. This difference affects heat conduction, expansion and high-temperature mechanical behaviour as well as magnetism. Ferritic grades can offer useful low expansion and resistance in certain sulfur-bearing gas environments. Heavily loaded components at high temperature present a different duty. Rather than describing 446 as a general replacement for 310S, it is more useful to understand its particular role where hot-gas chemistry is important.
Its relationship with 1.4742 and 1.4762
1.4742 and 1.4762 are also heat-resistant ferritic steels, but belong to a different composition group containing aluminium and silicon alongside chromium. Overlapping applications do not establish a shared EN number or chemical identity. Using 1.4762 and 446 interchangeably would obscure the distinction between two separate materials. They share a place in the heat-resistant ferritic family while retaining different alloy definitions.
Typical application areas
Hot-gas equipment, recuperators and protective tubes.
Product and cutting options
Relevant product forms for this material are listed below. Availability varies with grade and dimensions.