1.4104 (also known as SUS430F in Japanese industrial standards) is a ferritic stainless steel with added sulfur for improved machinability. It belongs to the 430-series stainless steels, which are popular for their balance of corrosion resistance, mechanical properties, and cost-effectiveness, particularly in applications requiring easy machining.
Chemical Composition
The key alloying elements in 1.4104 (SUS430F) are:
Element Content Range (%) Role
Carbon (C) ≤ 0.12 Enhances strength but may reduce corrosion resistance if excessive.
Chromium (Cr) 16.00 – 18.00 Primary element for corrosion resistance; forms a protective oxide layer.
Sulfur (S) 0.15 – 0.35 Improves machinability by breaking chip formation during cutting.
Manganese (Mn) ≤ 1.00 Aids in sulfur distribution and enhances strength.
Silicon (Si) ≤ 1.00 Enhances oxidation resistance and deoxidizes the alloy.
Phosphorus (P) ≤ 0.040 Limited to avoid brittleness.
Key Properties
1. Mechanical Properties
Tensile Strength: 450 – 600 MPa
Yield Strength: ≥ 205 MPa
Elongation: ≥ 20% (in 50 mm)
Hardness: ≤ 183 HB (annealed condition)
2. Corrosion Resistance
Moderate resistance to atmospheric corrosion, fresh water, and mild organic acids.
Inferior to austenitic stainless steels (e.g., 304, 316) due to lower chromium and lack of nickel.
Susceptible to pitting and crevice corrosion in harsh environments (e.g., saltwater, strong acids).
3. Machinability
Excellent machinability, rated ~85% compared to 1215 free-cutting steel (due to sulfur addition).
Suitable for high-speed machining, threading, and precision cutting operations.
4. Heat Treatment
Annealing: 700 – 800°C, followed by slow cooling to soften the material and improve ductility.
Cannot be hardened by heat treatment (ferritic stainless steels are non-hardenable via quenching).
Applications
1.4104 (SUS430F) is primarily used in applications requiring easy machining and moderate corrosion resistance:
Fasteners: Screws, bolts, and nuts for general-purpose use.
Automotive Components: Valves, brackets, and fittings in non-critical, low-corrosion environments.
Household Hardware: Hinges, handles, and decorative parts.
Machined Parts: Gears, shafts, and precision components where cost and machinability are prioritized over high corrosion resistance.
Comparison with Related Alloys
Alloy Machinability Corrosion Resistance Cost Key Use Case
1.4104 (430F) Excellent Moderate Low-Medium Machined parts, fasteners
1.4016 (430) Fair Moderate Low General structural parts
1.4301 (304) Fair High Medium Food processing, marine use
Limitations
Poor resistance to chloride-rich environments (e.g., coastal areas, saltwater).
Lower toughness at low temperatures compared to austenitic grades.
Not suitable for high-stress or high-corrosion applications (e.g., chemical processing).
In summary, 1.4104 (SUS430F) is a cost-effective ferritic stainless steel optimized for machinability, making it ideal for low-cost, precision-machined components in mild environments.