347
1.4550 · EN 10088 / AISI · 1.4550
347 is a stainless steel (Austenitic family) to EN 10088 / AISI (1.4550). It has a specified 0.2 % proof stress of 210 MPa and a typical tensile strength of about 520 MPa, with a uniform elongation of 40 %. Nominal carbon content is around 0.08 %. For nonlinear FEA, a bilinear model uses E = 193 GPa up to yield and a tangent modulus of 781 MPa above it. Its austenitic structure gives excellent corrosion resistance, formability and cryogenic toughness, but it cannot be hardened by heat treatment.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 40.0% · conservative analysis limit ½εu = 20.0%
Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.
Ratings — engineering judgement
Weldabilitygood
Readily weldable; use a matching low-carbon (L) filler to avoid sensitisation and keep interpass temperature down.
Machinabilitypoor
Work-hardens rapidly — use sharp carbide tooling, positive rake and firm feeds; avoid dwelling.
Corrosion resistanceexcellent
Excellent general and chloride resistance from the Cr–Ni(–Mo) alloying.
Hardenabilitynone
Cannot be hardened by heat treatment — strengthen only by cold work.
Toughnessexcellent
Outstanding toughness to cryogenic temperatures with no ductile-to-brittle transition.
Indicative ratings derived from composition and family — engineering guidance, not specification values.
Physical properties
| Density | 7990 | kg/m³ |
| Elastic modulus | 193 | GPa |
| Shear modulus | 74.2 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 16.0 | ×10⁻⁶/°C |
| Thermal conductivity | 15 | W/(m·K) |
| Specific heat | 500 | J/(kg·K) |
| Magnetic | No (annealed) |
Typical values for austenitic steel — use the mill certificate for the specific product.
Chemical composition (wt %)
Composition per EN 10088 / AISI for 347 (1.4550).
Available forms
Common applications
- Process, food and pharmaceutical equipment
- Architectural and marine hardware
- Fasteners and fittings for corrosive service
- Tanks, pipework and heat exchangers
History
The austenitic (chromium-nickel) stainless steels descend from the “18/8” patented at Krupp in 1912; adding nickel to a chromium steel stabilises the tough, formable, corrosion-resistant austenite phase. They are the largest and most widely used stainless family. Niobium-stabilised austenitic — like 321 but preferred for welded high-temperature pressure parts.
- 1912Strauss & Maurer patent 18/8 austenitic stainless at Krupp (Nirosta)
- 1930Molybdenum and stabilising (Ti/Nb) variants developed for chemicals and welding
- 1970Low-carbon (L) grades from argon-oxygen decarburisation (AOD) solve weld sensitisation
This profile is generated from the grade's core data and family. Composition is decoded from the designation where its naming system defines it; physical properties are family-typical and ratings are indicative. Confirm critical values against the governing standard or the mill certificate. Equivalents, historical designations and hand-written expert notes are added per grade over time.