F55 (S32760) Super Duplex Stainless Steel Bar

F55 is a high-performance super duplex stainless steel featuring:

Exceptional corrosion resistance in acidic, chloride, and sulfide environments
High strength with yield strength ~2x standard austenitic grades
Good weldability despite high alloy content
Wide temperature range (-50°C to 300°C) with stable mechanical properties

Chemical Composition (wt%)

Element	Minimum	Maximum
C	–	0.03
Si	–	0.8
Mn	–	1.2
P	–	0.03
S	–	0.01
Cr	24	26
Ni	6	8
Mo	3	4
N	0.2	0.3
Cu	–	1.0
W	–	1.0
Fe	Balance	–
Data sourced from ASTM A240/ASME SA-240

Property	Value
Density (g/cm³)	7.8
Hardness (HRC)	28-32 (annealed)
Yield Strength (MPa)	≥550
Tensile Strength (MPa)	≥800
Elongation (%)	≥25
Typical values after solution annealing

F55 super-duplex stainless steel bar, with its unique duplex microstructure (austenite and ferrite each comprising approximately 50% austenite) and carefully designed alloy composition, is a high-performance material for extremely corrosive environments. Its core properties include:

1. High Strength and Toughness: Yield strength exceeds 550 MPa, tensile strength reaches 750-900 MPa, and elongation remains above 25%, combining high load-bearing capacity with impact resistance.

2. Excellent Corrosion Resistance: The combination of chromium (24-26%), molybdenum (3-4%), tungsten (0.5-1%), and nitrogen (0.2-0.3%) gives it a pitting resistance equivalent of PREN ≥ 40, making it particularly resistant to chloride ion stress corrosion cracking and exhibiting excellent performance in seawater and acidic media.

3. Excellent Processability: After solution annealing, it can be processed by hot or cold forming, exhibiting excellent weldability and stable mechanical properties in the weld zone.

4. Non-magnetic: Suitable for use in electromagnetically sensitive environments, such as medical or precision instrument components.

F55 stainless steel bars are widely used in high-corrosion and high-stress environments:

1. Marine Engineering: Used in the manufacture of ship propulsion shafts, seawater pumps and valves, submarine pipelines, etc., offering seawater corrosion resistance and biofouling resistance.

2. Petrochemical: Used in downhole tools, pipelines, and reactor internals for H₂S-containing oil and gas wells, offering hydrogen sulfide corrosion resistance.

3. Energy: Used in nuclear power plant cooling system components and flue gas desulfurization equipment, offering resistance to high temperature, high pressure, and radiation environments.

4. Specialty Equipment: Used in chemical pumps and valves, food processing machinery, meeting sanitary corrosion resistance requirements.