Stainless steel grade data · UNS S24100 · XM-28
UNS S24100 Forgings Nitrogen-strengthened Cr-Mn austenitic stainless steel, also designated XM-28 and sold under the trade name Nitronic 32
UNS S24100 carries 11 to 14 percent manganese and 0.20 to 0.45 percent nitrogen in place of most of the nickel found in Type 304. The result is roughly twice the yield strength of Type 304 with broadly comparable corrosion resistance, at a chemistry far less exposed to the nickel price.
We melt this grade in-house and forge it to drawing: seamless rolled rings, flanges, shafts, round bars, discs, sleeves and tube sheets, to ASTM A314, A276 and A580.
- UNS
- S24100
- ASTM
- XM-28
- Trade name
- Nitronic 32
- Type
- Low-nickel, nitrogen-strengthened austenitic stainless
- Specs
- ASTM A314, A276, A580, A313
- Yield, min
- 379 MPa / 55 ksi, annealed
- Tensile, min
- 690 MPa / 100 ksi, annealed
- Forms
- Rings, flanges, shafts, bars, discs, sleeves, tube sheets
- Minimum
- 10 kg, no minimum piece count
- Lead time
- 20 to 60 days
- Enquiries
- sales@steelforgepieces.com
What UNS S24100 is, and what it is not
S24100 belongs to the Cr-Mn-N family. Manganese and nitrogen hold the austenite stable so that nickel can be cut to between 0.5 and 2.5 percent, and the nitrogen in solution does the strengthening work. Fabricability stays close to that of a conventional 300-series austenitic: it forms, welds and forges by the usual methods, and it stays essentially non-magnetic even after heavy cold work.
A note on the 310H reference
Older listings for this grade, including an earlier version of this page, paired UNS S24100 with AISI 310H. That pairing is wrong. AISI 310H is a 25 chromium, 20 nickel heat-resisting grade for sustained high-temperature service. S24100 is a low-nickel, high-manganese, nitrogen-bearing grade. The two share neither chemistry nor service behaviour and cannot be substituted for one another.
If a drawing you hold calls for S24100 and 310H together, send it to us before ordering and we will confirm with you which alloy the design actually needs.
| Item | Detail |
|---|---|
| UNS number | S24100 |
| ASTM designation | XM-28 |
| Trade name | Nitronic 32, a registered trademark of AK Steel |
| Alloy family | Nitrogen-strengthened chromium-manganese austenitic stainless steel |
| Specifications met | ASTM A314 · ASTM A276 · ASTM A580 · ASTM A313 |
| Mill product forms | Ingot, forging billet, bar and plate |
| Supplied condition | Annealed, or cold worked for bar and wire products |
| Magnetic response | Permeability 1.008 annealed, 1.011 after 70 percent cold draw, measured at H = 200 oersteds and 70 °F |
Chemical composition
Published limits differ slightly between sources. Electralloy's data sheet gives chromium as 16.50 to 19.00 percent and phosphorus as 0.045 percent maximum; the wider UNS listing gives 16.5 to 19.5 percent chromium and 0.06 percent phosphorus maximum. Both ranges appear below. We melt and certify to whichever specification your order names.
| Element | Per Electralloy data sheet | Per UNS listing | Function |
|---|---|---|---|
| Carbon | 0.15 max | 0.15 max | Strength. The relatively high limit is why sensitisation has to be avoided. |
| Manganese | 11.00 to 14.00 | 11 to 14 | Austenite stabiliser taking the place of most of the nickel |
| Chromium | 16.50 to 19.00 | 16.5 to 19.5 | Passive film, corrosion resistance |
| Nickel | 0.50 to 2.50 | 0.5 to 2.5 | Austenite stability and toughness, kept deliberately low |
| Nitrogen | 0.20 to 0.45 | 0.2 to 0.45 | The principal strengthener in this grade |
| Silicon | 1.00 max | 1 max | Deoxidiser |
| Phosphorus | 0.045 max | 0.06 max | Residual, controlled |
| Sulfur | 0.030 max | 0.03 max | Residual, controlled for hot workability |
| Iron | Balance | Balance | Matrix |
Why in-house melting matters on a nitrogen-alloyed grade
Nitrogen is the strengthening element here, and it is the element most easily lost or over-shot during melting. Our vacuum oxygen decarburisation units, at 30 t and 60 t, exist precisely to hold nitrogen and carbon where the specification wants them on stainless and duplex grades, and our 3 t and 6 t protective-atmosphere electroslag furnaces are used for nitrogen-alloyed steels where cleanliness also governs. Because the heat is made here, the nitrogen result is ours to control rather than something inherited from a purchased billet certificate.
Mechanical and physical properties
Tensile requirements, annealed, ASTM A276
| Property | Metric | Imperial |
|---|---|---|
| Ultimate tensile strength, min | 690 MPa | 100 ksi |
| 0.2 percent offset yield strength, min | 379 MPa | 55 ksi |
| Elongation, min | 30 percent | 30 percent |
| Reduction of area, min | 50 percent | 50 percent |
| Hardness, typical annealed bar | 92 HRB | 92 HRB |
Annealed Type 304 is normally specified at 515 MPa tensile and 205 MPa yield. That comparison is the basis for the mills' statement that S24100 delivers approximately twice the yield strength of Type 304.
Physical and thermal data
| Property | Value | Condition |
|---|---|---|
| Density | 7.781 g/cm³ (0.281 lb/in³) per Electralloy; 7.83 g/cm³ (0.283 lb/in³) per the UNS listing | Room temperature |
| Melting range | 1418 to 1446 °C (2585 to 2635 °F) per Electralloy; 1450 to 1510 °C quoted elsewhere | Use the ordering mill's figure for process design |
| Modulus of elasticity | 200 GPa (29 × 106 psi) | At 21 °C / 70 °F |
| Specific heat | 0.12 Btu/lb·°F | 0 to 100 °C / 32 to 212 °F |
| Electrical resistivity | 27.6 microhm-in | At 21 °C / 70 °F |
| Thermal expansion, mean | 9.4 × 10-6/°F (16.9 × 10-6/°C) over 23 to 204 °C 10.7 × 10-6/°F (19.3 × 10-6/°C) over 23 to 649 °C 11.6 × 10-6/°F (20.9 × 10-6/°C) over 23 to 982 °C | From room temperature |
| Magnetic permeability | 1.008 annealed; 1.011 after 70 percent cold draw | H = 200 oersteds, 70 °F |
Forging, heat treatment and fabrication
S24100 takes no hardening response from heat treatment. Everything above the annealed minimum comes from cold work, and the alloy work-hardens quickly, which drives both the machining parameters and the in-process annealing schedule.
2050 to 2200 °F
Recommended hot working range, 1121 to 1204 °C. A common forging practice is to heat to 1093 °C (2000 °F), soak to equalise, then raise to 1177 °C (2150 °F) and equalise again before the first blow.
1900 to 2050 °F
Anneal at 1038 to 1121 °C, commonly 1066 °C (1950 °F), then cool rapidly in water or air. In-process anneals run 1900 to 2000 °F.
Cold work only
The alloy does not harden by heat treatment. Strength above the annealed condition is obtained by cold working.
30 percent of B1112
Characteristics resemble Type 304, but the higher strength and rapid work hardening call for lower cutting rates, positive feeds, rigid setups and generous resulfurised lubricant.
No preheat required
Weldable by gas tungsten arc, gas metal arc, shielded metal arc and submerged arc. Control heat input to limit sensitisation.
Standard methods
Formed by the same methods used for other austenitic stainless steels. Well suited to simple cold-headed parts needing high mechanical properties.
Corrosion behaviour, stated plainly
In weak acid solutions and pitting media, the corrosion resistance of S24100 approaches that of Type 304. In more aggressive media it is somewhat less corrosion resistant than Type 304. Because of its higher carbon content it is also less resistant to intergranular attack than Type 304, and it will not pass ASTM A262 testing after sensitisation at 1250 °F.
Where we would quote a different grade
S24100 is the wrong choice for warm chloride-bearing seawater systems, strong sulphuric or mixed acid duty, and sour service under NACE MR0175 / ISO 15156. For those environments we would normally offer A182 F53 or A182 F55 super duplex, A182 F44, 904L, or a nickel alloy such as Inconel 625.
Tell us the medium, the temperature, the chloride level and the pressure, and you will get a grade recommendation rather than simply a price for the grade you named.
Where UNS S24100 is used
The uses below are the ones mill literature actually lists for this grade. Each one plays to the same combination: high strength, low nickel content, non-magnetic behaviour and atmospheric corrosion resistance in the Type 304 class.
| Application | Property being used | Form we supply |
|---|---|---|
| Clamps for pole line hardware | High strength in cold-headed parts, outdoor service | Forged blanks, bar |
| Concrete reinforcing accessories | Strength with non-magnetic behaviour | Forged bar |
| Shafting | Twice the yield of 304 at a lower nickel content | Forged shafts, stepped shafts, spindles |
| Dam gate stems | Strength and fresh-water corrosion resistance | Forged round bar, machined stems |
| Skid wire for underground transmission lines | Non-magnetic, abrasion resistant | Ingot and forging billet |
| Abrasion and corrosion-resistant screens | Rapid work hardening at the surface | Forged frames and rings |
| High strength non-magnetic springs and wire forms | Permeability near 1.01 even after heavy cold work | Billet to ASTM A313 and A580 |
| Racks, cages, fasteners, communication hardware | Cost-effective alternative to 300-series grades | Forged blanks, discs, sleeves |
What we can forge in this grade
Every item is forged to your drawing from steel melted on this site. No welding, no casting, no purchased billet of unknown origin. Forging, heat treatment, machining and testing all happen inside the works.
| Product | Size limit | Set by |
|---|---|---|
| Seamless rolled rings | OD 50 mm to OD 6,000 mm | 6 m, 3 m and 1 m radial-axial ring mills; upset-and-punch route below ring-mill range |
| Forged shafts | Up to 14,000 mm turned length | C61160 horizontal lathe; 15 m well furnace for vertical quenching |
| Discs, tube sheets, blocks | Up to 5,000 mm machined diameter | 5,000 mm vertical turning lathe |
| Bored sleeves and hollow shafts | Up to 1,600 mm dia × 10,000 mm | CNC deep-hole drilling machine |
| Single-piece weight | Up to 30,000 kg | 60 t maximum heat size; 6,300 t hydraulic press |
| Minimum order | 10 kg, no minimum piece count | Weight-based, so one-off parts are quotable |
Forms produced
Seamless rolled rings and contoured rolled rings, forged rings, weld neck and blind and slip-on flanges, forged round bars and blocks, stepped and eccentric shafts, discs and tube sheets, sleeves and bushings, hollow forged cylinders, and valve components including bodies, bonnets, stems and seat rings.
Testing and certification
Chemistry is verified at the furnace by optical emission spectrometry to ASTM E415, with infrared carbon and sulfur analysis to ASTM E1019 and handheld positive material identification on the finished part. Tensile testing runs on 600 kN and 300 kN machines to ASTM A370, with Charpy V-notch impact testing to minus 60 °C. Ultrasonic examination follows ASTM A388 and EN 10228-3, magnetic particle inspection follows ASTM E709, and grain size is measured to ASTM E112. Certificates are issued to EN 10204 3.1, or to 3.2 witnessed by BV, DNV, LR, SGS, TUV or your own inspector. Intergranular corrosion testing to ASTM A262 or G28, where a specification calls for it, is placed with an accredited third-party laboratory and the report travels with the mill certificate.
Questions we are asked about this grade
Is UNS S24100 the same as AISI 310H?
No. UNS S24100 is XM-28, also known as Nitronic 32, a low-nickel chromium-manganese austenitic stainless steel carrying 11 to 14 percent manganese and 0.20 to 0.45 percent nitrogen. AISI 310H is a high-chromium, high-nickel heat-resisting grade. The two have different compositions, different strengths and different service temperatures, and they are not interchangeable.
Is UNS S24100 the same as Nitronic 32?
Yes. Nitronic 32 is the trade name under which UNS S24100, ASTM XM-28, is sold. Nitronic is a registered trademark of AK Steel. An order for Nitronic 32 forgings and an order for UNS S24100 forgings specify the same chemistry.
How strong is UNS S24100 compared with Type 304?
In the annealed condition ASTM A276 requires a minimum 0.2 percent yield strength of 379 MPa (55 ksi) and a minimum tensile strength of 690 MPa (100 ksi). That is approximately double the yield strength normally specified for annealed Type 304, and it comes from nitrogen in solution rather than from added nickel.
Can UNS S24100 be hardened by heat treatment?
No. The grade takes no hardening response from heat treatment. Additional strength comes from cold work. Heat treatment is limited to annealing at 1038 to 1121 °C, commonly 1066 °C, followed by rapid cooling in water or air.
Is UNS S24100 suitable for seawater or strong acid service?
Generally no. Corrosion resistance approaches Type 304 in weak acids and pitting media but falls below Type 304 in more aggressive environments, and the higher carbon content leaves the grade open to intergranular attack once sensitised. For seawater, chloride-rich service or strong acids, super duplex, 6Mo, 904L or a nickel alloy is the appropriate choice.
Is UNS S24100 magnetic?
It is essentially non-magnetic. Relative permeability measures 1.008 in the annealed condition and 1.011 after a 70 percent cold draw, both at H = 200 oersteds and 70 °F. That stability under cold work is why the grade is used for non-magnetic springs and for hardware on electrical transmission lines.
What temperature should UNS S24100 be forged at?
The recommended hot working range is 1121 to 1204 °C, or 2050 to 2200 °F. A widely used practice is to heat to 1093 °C (2000 °F), soak until the section has equalised, then raise to 1177 °C (2150 °F) and equalise again before forging begins. In-process annealing is carried out between 1900 and 2000 °F.
Which specifications can you certify this grade to?
ASTM A314 for forging billet and bar, ASTM A276 for bars and shapes, and ASTM A580 and A313 for wire products. Certificates are issued to EN 10204 3.1, or to 3.2 countersigned by a third party on request. The works holds CCS, BV, DNV, LR and NK approvals.
What is the minimum order, and how long does it take?
Minimum order is 10 kg with no minimum piece count, so a single part is quotable. Normal lead time is 20 to 60 days from order confirmation. A standard stainless grade forged without a remelting step sits at the lower end of that range; witnessed third-party inspection or outside laboratory corrosion testing needs scheduling, so flag both at enquiry stage and they will be built into the quoted date rather than added to it.
Request a quotation
Send the grade, the dimensions or a drawing, the quantity, the delivery condition, the testing and certification requirements, and the destination port. With those six items we can return a firm price, usually within two working days.
Jiangyin Jiangnan Metal Co., Ltd.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China
Telephone, WhatsApp and WeChat: +86 189 2135 9659
Email: sales@steelforgepieces.com
Business hours: Monday to Saturday, 08:00 to 17:30 China Standard Time (UTC+8)