AISI 431 UNS S43100 Martensitic Stainless Steel Bars and plates
UNS S43100, commercially known as AISI 431, is a premium nickel-alloyed martensitic stainless steel defined by ASTM A276 and A479 standards. Unlike standard 420-series martensitic grades, UNS S43100 incorporates deliberate nickel additions, which significantly enhance its toughness, impact resistance, and mild corrosion resistance without sacrificing heat-treatable hardness and mechanical strength. This grade features excellent through-hardening performance, enabling stable and uniform mechanical properties after precise quenching and tempering. It is exclusively supplied in fully annealed soft condition, offering superior machinability for custom precision processing. Critical note: UNS S43100 has similar but non-identical chemical and mechanical scopes with SUS431 and EN 1.4057 (X17CrNi16-2). These grades are not fully interchangeable for critical engineering and offshore projects, and the required standard must be specified in formal orders.
Applications of UNS S43100
UNS S43100 is specially engineered for mechanical components requiring a balanced combination of high tensile strength, exceptional toughness, wear resistance, and moderate atmospheric & marine corrosion resistance. It outperforms ordinary 410/420 stainless steel under cyclic load, shock load, and mild corrosive working conditions, making it irreplaceable for heavy-duty industrial and marine applications. Typical products include high-strength industrial fasteners, heavy-duty bolts and studs, pump shafts, valve stems, mechanical drive shafts, coupling parts, and hydraulic component parts. It is widely used in general machinery, marine auxiliary equipment, petrochemical auxiliary facilities, and conventional aerospace non-critical structural fittings. Not suitable for strong acid, strong alkali or severe salt corrosion environments, and it is the preferred grade for high-reliability mechanical parts that require long service life after heat treatment.
Equivalent Grades and Commonly Used Specifications of UNS S43100
| Steel Grade | Specification | Steel Grade | Specification | |
| 1Cr17Ni2 / 14Cr17Ni2 / S43110 | GB/T 1220 | 17Cr16Ni2 / S43120 | GB/T 1220 | |
| GB/T 1221 | GB/T 1221 | |||
| GB/T 4356 | GB/T 4356 | |||
| GJB 2294A | UNS S43100 /
431 |
ASTM A276/A276M | ||
| 14X17H2 | GOST 5632 | ASTM A240/A240M | ||
| UNS S43100 | ASTM A276/ A276M | ASTM A493 | ||
| ASTM A479 / A479M | 1.4057 / X17CrNi16-2 | EN 10088-3 | ||
| ASTM A240 / A240M | SUS431 | JIS G 4303 | ||
| / | / | JIS G 4308 | ||
| 14X17H2 | GOST 5632 | |||
| Produce as other form and size according to technical requirements are available. | ||||
Typical Chemical Composition of UNS S43100
|
Specification |
Steel Grade | Elements% | ||||||
| C | Si | Mn | P | S | Ni |
Cr |
||
|
ASTM A276 |
UNS S43100 | 0.20 | 1.00 | 1.00 | 0.040 | 0.030 | 1.25-2.50 | 15.0-17.0 |
| GB/T 1220 |
1Cr17Ni2 |
0.11~0.17 | 0.80 | 0.80 | 0.040 | 0.030 | 1.50~2.50 |
16.00~18.00 |
|
17Cr16Ni2 |
0.12~0.22 | 1.00 | 1.50 | 0.040 | 0.030 | 1.50~2.50 |
15.00~17.00 |
|
| Produce as other form and size according to technical requirements are available. | ||||||||
Typical Heat Treatment Condition and Mechanical Properties of UNS S43100
|
Specification |
Steel Grade | Delivery Condition | Mechanical Properties of Heat-Treated Specimens | ||||||
| Rp0.2/(N/mm2) | Rm/(N/mm2) | A/% | Zb/% | Aku2d/J | HBW |
HRC |
|||
|
ASTM A276 |
UNS S43100 | Annealed | / | / | / | / | / | ≤285 | / |
| quenched （1020℃, Oil) | / | / | / | / | / |
≥40 |
|||
|
GB/T 1220 |
1Cr17Ni2 |
Annealed（600-700℃, air） | / | / | / | / | / | ≤285 | / |
|
Q+T（950℃-1050℃, oil; 275℃-350℃, air） |
/ | ≥1080 | ≥10 | / | ≥39 | / |
/ |
||
|
17Cr16Ni2 |
Annealed（680-800℃, air） |
/ | / | / | / | / | ≤295 |
/ |
|
|
Q+T（950℃-1050℃, oil/air; 600℃-650℃, air） |
≥700 | 900~1050 | ≥12 | ≥45 | ≥25 | / | / | ||
| ≥600 | 800~950 | ≥14 | ≥45 | ≥25 | / |
/ |
|||
| Produce as other form and size according to technical requirements are available. | |||||||||
Product Forms and Size Range of UNS S43100
|
Product forms |
Size range |
|
Bars |
Diameter or side length: 5.0mm~1000mm |
| Flats |
thickness: 4.0mm~1000mm width: 300mm~2200mm |
| Produce as other form and size according to technical requirements are available. | |
