X17CrNi16-2 (431)

Precipitation-capable martensitic stainless with moderate corrosion resistance and high strength. For marine pump shafts and fasteners.

Stainless Steels Martensitic Stainless Steel ENX17CrNi16-2 DIN1.4057 AISI/SAE431 ASTMA276 Type 431 +12
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Description

X17CrNi16-2 (EN 1.4057 / AISI 431) per EN 10088. Higher Cr (16%) than standard martensitic grades (420) plus Ni addition (2%) significantly improves corrosion resistance while maintaining hardenability. Achieves HRC 28-38 in Q+T condition with Rm 900-1100 MPa and good resistance to marine atmospheres. Standard for marine and offshore fasteners, pump shafts and valve stems.

Key Properties — Annealed
Rm (Tensile Strength)
800 – 1,000
MPa
Re / Rp0.2 (Yield)
600 – 800
MPa
A₅ (Elongation)
≥ 14.0
%
Hardness
— – 285
HB
E (Young's Modulus)
215
GPa
Density
7.73
g/cm³
Main Designations (16)
Standard BodyDesignationCountry / RegionNote
EN X17CrNi16-2 European Union
DIN 1.4057 Germany
AISI/SAE 431 USA
ASTM A276 Type 431 USA
BS EN 431S29 UK
JIS SUS431 Japan
GOST 20H17N2 (20Kh17N2) Russia / CIS
UNI X17CrNi16-2 Italy
NF Z15CN16-02 France
SS 2321 Sweden
PN 2H17N2 Poland
CSN 17043 Czech Republic
UNS S43100 USA (UNS)
GB 14Cr17Ni2 China
JUS C.4181 Yugoslavia / Serbia Martensitic Cr-Ni stainless; JUS C.B2.070
ISO X17CrNi16-2 International
Standards (16)
#Standard BodyDesignationCountry / RegionNote
1 EN X17CrNi16-2 European Union
2 DIN 1.4057 Germany
3 AISI/SAE 431 USA
4 ASTM A276 Type 431 USA
5 BS EN 431S29 UK
6 JIS SUS431 Japan
7 GOST 20H17N2 (20Kh17N2) Russia / CIS
8 UNI X17CrNi16-2 Italy
9 NF Z15CN16-02 France
10 SS 2321 Sweden
11 PN 2H17N2 Poland
12 CSN 17043 Czech Republic
13 UNS S43100 USA (UNS)
14 GB 14Cr17Ni2 China
15 JUS C.4181 Yugoslavia / Serbia Martensitic Cr-Ni stainless; JUS C.B2.070
16 ISO X17CrNi16-2 International
All values in wt.%
C
Carbon
0.1200 – 0.2200
Si
Silicon
≤ 1.0000
Mn
Manganese
≤ 1.5000
Cr
Chromium
15.0000 – 17.0000
Ni
Nickel
1.5000 – 2.5000
ElementSymbolMin %Max %Typical %
Carbon C 0.1200 0.2200 0.1700
Silicon Si 1.0000 0.5000
Manganese Mn 1.5000 0.6000
Chromium Cr 15.0000 17.0000 16.0000
Nickel Ni 1.5000 2.5000 2.0000
Mechanical Properties
ConditionCode Rm min
MPa
Rm max
MPa
Re min
MPa
Re max
MPa
A₅ min
%
Z
%
KV
J
HB minHB max HRC minHRC max E
GPa
Annealed +A 800 1,000 600 800 14.0 45.0 285 215.0
Q+T 700 C +QT700 850 1,050 700 850 12.0 45.0 295 215.0
Q+T 600 C +QT600 1,000 1,200 800 1,000 10.0 40.0 350 28.0 38.0 215.0
Physical Properties
Density
7.730
g/cm³
Melting Point
1450–1510
°C
Young's Modulus
215.0
GPa
Poisson's Ratio
0.280
Thermal Conductivity
25.0
W/m·K
Thermal Expansion
10.20
×10⁻⁶ /K
Specific Heat
460
J/kg·K
Electrical Resistivity
0.7200
µΩ·m
Magnetic
Yes
 
Heat Treatment
Annealing
Temperature:750°C – 820°C
Medium:Furnace
Duration:3-6 h
Cooling:<=30 C/h
Hardness After:<=HB 260
Before machining.
Austenitizing
Temperature:980°C – 1050°C
Medium:Oil or air (thin sections)
Duration:20-30 min
Cooling:Oil quench
Hardness After:HRC 35-45
Better corrosion resistance than 420 in hardened condition.
Tempering
Temperature:580°C – 700°C
Medium:Air
Duration:2h
Cooling:Air cool
Hardness After:HRC 25-38
Avoid 400-600 C temper embrittlement range.
Machinability
Machinability Rating
relative to AISI B1112 = 100%
52.0%
Difficult
Turning Speed (HSS)
30
m/min
Turning Speed (Carbide)
145
m/min
Feed Rate (Turning)
0.180
mm/rev
Drilling Speed (HSS)
22
m/min
Milling Speed (Carbide)
148
m/min
CoolantSoluble oil 8-10%
Chip FormationShort-medium chips
Tool MaterialCarbide M10/P20
Surface FinishRa 0.4-1.6 um
Easier to machine than austenitics. Machine in annealed condition.
Applications
Marine & Offshore
Marine pump shafts, propeller shafts, rudder stocks and offshore fasteners.
Fasteners
High-strength corrosion-resistant bolts and studs for marine and chemical service.
Oil & Gas
Valve stems, wellhead components and Christmas tree bolting.
Technical Notes
💧
vs 420
431 (16%Cr+Ni) significantly outperforms 420 (13%Cr) in corrosion resistance. Standard choice where moderate corrosion resistance plus high strength is needed.
🔥
Weldability
Difficult. Pre-heat 200-300 C. Use Inconel 82/182 filler for dissimilar-metal joints.