AISI 430Nb (1.4511, X3CrNb17) – Ferritic stainless steel
Online data sheet according to DIN EN 10088-3 for material 1.4511
The material AISI 430Nb is a niobium-stabilised ferritic stainless steel, also known under the designations 1.4511 and X3CrNb17. The addition of niobium reduces the formation of carbides and significantly increases resistance to intergranular corrosion. This stainless steel has good corrosion resistance (PREN value approx. 18 to 20), but is not suitable for prolonged contact with seawater. The material is magnetic (ferromagnetic), easy to polish and has a density of 7.7 kg/dm³. When exposed to oxidation, 1.4511 is temperature-resistant for short periods up to approx. 870 °C, but can only be used mechanically up to approx. 600–700 °C. In a soft-annealed condition, the material has a tensile strength of 350 to 550 N/mm² and a hardness of ≤ 185 HB. Thanks to its stabilisation, 1.4511 has comparatively good weldability and hot formability during forging. Typical areas of application for 430Nb stainless steel are the chemical industry, automotive engineering (e.g. for exhaust systems) and mechanical engineering.
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Properties at a glance
Elongation at break (A): ≥ 20 %
Density: 7.7 kg/dm³
Cold forming: Possible
Corrosion resistance: Good
Mechanical properties: Medium
Magnetic: Yes (ferromagnetic)
Magnetisable: Yes
Polishability: Good
PREN value: 18-20
Forging: Good
Weldability: Possible
Machining: Possible
Yield strength (Rp0.2): ≥ 240 MPa
Machinability: Medium
Tensile strength: 350 - 550 N/mm²
Specifications of the material
EN material number: 1.4511
EN short name: X3CrNb17
EN standard: 10088-3
Microstructure class: Ferritic stainless steel
Comparable standards and designations
AFNOR Z4CNb17
AISI 430Nb
DIN 17440
JIS SUS430LX
RVS 430Nb
The chemical composition of stainless steel AISI 430Nb (1.4511, X3CrNb17) is specified in mass percent according to DIN EN 10088-3 as follows:
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Carbon (C): ≤ 0.05
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Silicon (Si): ≤ 1.00
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Manganese (Mn): ≤ 1.00
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Phosphorus (P): ≤ 0.040
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Sulphur (S): ≤ 0.015
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Chromium (Cr): 16.0 - 18.0
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Niobium (Nb): min. 8 x C to max. 1.00
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Nitrogen (N): ≤ 0.030
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Nickel (Ni): ≤ 0.50
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Molybdenum (Mo): ≤ 0.20
Physical properties
Thermal conductivity (at 20°C): 25
Electrical resistivity at room temperature (in Ω mm²/m): 0.60
Specific heat capacity (at 20°C): 460
Mechanical properties
These specifications refer to mechanical properties for ≤ 100 (Ø in mm) in a soft-annealed condition.
Hardness in HB: ≤ 185
Yield strength Rp0.2 in MPa: ≥ 240
Strength / tensile strength Rm in MPa: 350 - 550 N/mm²
Elongation at break A in %: ≥ 20
Weldability: Ferritic steel 430Nb (1.4511, X3CrNb17) is weldable, but this should be done with caution to avoid grain growth and embrittlement. Suitable welding processes are laser welding, plasma welding and TIG welding.
Welding process: The material must be clean and free of contamination before welding. As a rule, no heat treatment is required. To prevent grain growth, the welding energy should be kept as low as possible, ideally below 1 kJ/mm. Shielding gases without hydrogen or nitrogen content should be used. Bright annealing and scale must be completely removed after welding.
Welding filler material: The austenitic material 1.4316 (MT-308L) is suitable as a welding filler material.
Post-weld heat treatment: Post-weld heat treatment is not usually necessary for the material AISI 430Nb. It is only carried out on larger components or for specific high requirements, as improper post-treatment can lead to grain growth and embrittlement. Without this additional heat treatment, the mechanical properties in the weld seam and the heat-affected zone may differ significantly from those of the base material.
Forging
Ferritic stainless steel 430Nb has good forgeability. For shaping, the material should be preheated to approximately 1100°C to 1130°C. Forging takes place in the temperature range from 1130°C to approximately 800°C. Subsequent cooling in air is generally not critical. To relieve any residual stresses that may have arisen and improve the structural properties, soft annealing at 750°C to 850°C may follow. The material is suitable for both open die forging and drop forging.
Machinability, cold forming and cold upsetting
Machinability: Ferritic stainless steel AISI 430Nb (1.4511, X3CrNb17) has average machinability. Due to its ferritic structure, there is less work hardening during machining and therefore reduced heat generation at the cutting edge, which reduces tool wear. The ferritic structure results in the formation of short chips.
Cold forming: The material is generally suitable for cold forming. However, due to its ferritic structure, its ductility is limited and brittle fracture may occur if the plastic deformation is too severe. Forming stresses can be reduced by subsequent heat treatment, e.g. soft annealing.
Cold heading: The material 430Nb is only suitable for cold upsetting to a limited extent, as its low formability can lead to embrittlement and crack formation. In addition, tool wear can increase significantly with this application.
Corrosion resistance
Ferritic chromium steel AISI 430Nb (1.4511) has good corrosion resistance (PREN value approx. 18–20). It is resistant to atmospheric influences such as rain, air humidity and natural fresh water. The material can also be used in contact with mildly aggressive media, e.g. soap solutions or standard cleaning agents with low chloride concentrations. However, the material is not suitable for use in swimming pools with added chlorine or for prolonged contact with salt water (sea water). This could damage the passive layer, leading to the formation of pitting corrosion. In the non-welded state, the steel has good resistance to intergranular corrosion, which is supported by niobium stabilisation.
Applications of stainless steel AISI 430Nb / 1.4511
Ferritic stainless steel AISI 430Nb (1.4511, X3CrNb17) is characterised by its good corrosion resistance, high temperature resistance to oxidation and good formability. The material is therefore suitable for numerous industrial applications. Below we offer you an overview of the industries and possible products that are manufactured from this material:
Automotive industry: Stainless steel 430Nb is often used in vehicle exhaust systems, e.g. for silencers, catalytic converter housings, exhaust pipes and heat shields. Its good resistance to oxidation at elevated temperatures makes it ideal for components that are exposed to thermal stress.
Apparatus and container construction: This stainless steel is used here for the manufacture of heat exchangers, pipes and containers, especially when extremely aggressive media or very high chloride concentrations are not present.
Construction industry: The material is used for heat exchangers, simple pipes and containers, provided that no highly aggressive media or high chloride concentrations are present. Its good corrosion resistance is sufficient for many industrial process waters and weakly oxidising media.
Chemical and petrochemical industry: Stainless steel 430Nb is used in the manufacture of pipes and containers that must withstand moderate temperatures and weakly aggressive media, such as certain concentrations of nitric acid.
Household appliances: The material is also used in various household appliances, where its good polishability and corrosion resistance make it suitable for cladding, internal parts or heat-resistant components.
Mechanical engineering: In mechanical engineering, AISI 430Nb (1.4511) is often used to manufacture machine parts, fasteners such as screws and nuts, and other components that require good corrosion resistance and improved mechanical properties after forming.
The data provided in this data sheet or material information sheet has been compiled to the best of our knowledge and is based on the current version of the relevant standard. We do not accept any liability for any errors.
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