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UNS S43100 Martensitic Stainless Steel – High-Strength Toughness Alloy

Feb 28, 2026

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Contents
  1. What is the UNS S43100 Martensitic Stainless Steel?
  2. Key Characteristics of UNS S43100 Martensitic Stainless Steel
  3. Chemical Composition (wt%) of UNS S43100 SS
  4. Mechanical Properties of UNS S43100 SS
  5. Equivalent Grades of UNS S43100 SS
  6. UNS S43100 (AISI 431 / 1.4057) Martensitic Stainless Steel 2026 Export Reference Price
  7. Applications of UNS S43100 SS
  8. UNS S43100 SS Suppliers
  9. FAQ

What is the UNS S43100 Martensitic Stainless Steel?

UNS S43100 is a nickel-bearing martensitic stainless steel engineered to deliver enhanced toughness, ductility and corrosion resistance compared with standard martensitic grades such as S41000 and S42000. With 15.0-17.0% chromium and 1.25-2.50% nickel, it offers superior toughness and corrosion protection for high-stress structural components.
 

Key Characteristics of UNS S43100 Martensitic Stainless Steel

Martensitic structure provides magnetic properties.
Heat-treatable to achieve high strength while maintaining good ductility - a key advantage over other martensitic grades.
Better weldability than S42000, though post-weld heat treatment is recommended to restore corrosion resistance.
Cost-effective, prioritizing strength and toughness for automotive, aerospace and industrial high-stress applications.
 

Chemical Composition (wt%) of UNS S43100 SS

C
Cr
Ni
Mn
Si
P
S
≤0.20
15.00-17.00
1.25-2.50
≤1.00
≤1.00
≤0.040
≤0.030
 

Mechanical Properties of UNS S43100 SS

Condition
Tensile Strength
Yield Strength
Elongation
Hardness
Annealed
≥725 MPa
≥515 MPa
≥15%
≤241 HB
Heat-treated
≥1000 MPa
≥700 MPa
≥10%
≥285 HB
 

Equivalent Grades of UNS S43100 SS

Standard
Designation
AISI / SAE
431
EN
1.4057 (X17CrNi16-2)
GB
17Cr16Ni2
JIS
SUS431
 

UNS S43100 (AISI 431 / 1.4057) Martensitic Stainless Steel 2026 Export Reference Price

Product Form Specification Description FOB Reference Price (USD/kg, 2026)
Hot‑rolled black round bar Φ20‑200 mm, black surface, ASTM A276, batch ≥ 1 ton 1.80‑2.30
Peeled / turned round bar Φ20‑150 mm, peeled‑turned finish, EN10204‑3.1 2.20‑2.80
Bright drawn bar Small diameter Φ6‑20 mm, bright drawn 2.60‑3.40
Forgings / forged bar Large‑size forging, quenched & tempered heat treatment 3.00‑4.20
Plate / flat bar Hot‑rolled plate & flat bar 2.40‑3.20
These are FOB China port reference prices in USD/kg, for website and inquiry reference only. Actual prices fluctuate with nickel‑chromium market, dimensions, surface finish, order quantity and certification requirements. Not a formal quotation.
 

Applications of UNS S43100 SS

1.Marine & Shipbuilding
Pump shafts, propeller shafts, marine fasteners and valve stems for salt‑spray and marine‑atmosphere service (not for continuous full seawater immersion).
2.Valve & Pump Components
Valve stems, seats, trims, pump sleeves and impellers for medium‑pressure service with water, hydrocarbons and mild corrosive fluids.
3.High‑Strength Fasteners
Bolts, studs, nuts for petrochemical and power‑plant equipment under cyclic load.
4.Aerospace Components
Structural fittings, tie rods and auxiliary landing‑gear parts requiring high strength‑to‑weight ratio and moderate corrosion resistance.
5.Hydraulic & Power‑Machinery Parts
Hydraulic piston rods, spindles, compressor rotors, small turbine shafts for high‑stress service with wear plus slight corrosion.
6.Medical & Precision Instruments
Surgical instruments requiring good hardness, polishability and moderate rust resistance.
7.Petrochemical & General Machinery
Roll journals for paper‑making / textile machinery, shaft parts for oil‑field equipment under mildly corrosive conditions.
S43100 Stainless Steel Hydraulic Piston Rod

S43100 Stainless Steel Hydraulic Piston Rod

S43100 Stainless Steel Marine Pump ShaftS43100 Stainless Steel Marine Pump Shaft

S43100 Martensitic Stainless Steel High-Strength Fasteners

S43100 Martensitic Stainless Steel High-Strength Fasteners

UNS S43100 SS Suppliers

If you have project requirements for stainless steel, we welcome your order. GNEE has a large inventory of popular products for you to choose from. It can be processed into various practical product forms, including plates, coils, tubes, bars, wires, etc. For detailed chemical composition information and free samples, please contact our factory immediately. We offer competitive prices and excellent service.Email: info@gneestainless.com

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If you are planning a project, let me know:

What specific product form you need (e.g., round bar, sheet, fasteners)

The required heat treatment condition or mechanical strength target

I can help provide further processing or sourcing details.

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FAQ

1.How does S43100 compare with 420 and 304?

Compared with grade 420: S43100 contains nickel for improved toughness and corrosion resistance, better comprehensive performance after quenching & tempering. Compared with 304: S43100 delivers much higher strength and hardness, but lower corrosion resistance. It is magnetic and requires heat treatment for strength gain.

 

2.What hardness can UNS S43100 reach?
After quenching and tempering, typical hardness is HRC 35‑45. Annealed soft condition (HB ≤285) is also available for customer machining and subsequent heat treatment
 
3.Does 431 stainless steel weld well?

Poor weldability, welding is not recommended. If welding is unavoidable, full post‑weld heat treatment is mandatory to prevent cracking. Forged or bar‑stock machined parts are preferred

 

4.What service environment should we avoid for UNS S43100?

Avoid continuous full seawater immersion, high‑chloride environment, strong acid or alkali service. Maximum continuous service temperature is approximately 400 °C.

 

 

 

 

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