Stainless Steel S44635
UNS S44635
S44635 (MONIT) is a 25Cr-4Mo-4Ni super-ferritic stainless steel in which nickel is added for toughness, supplied as annealed sheet, plate and tube plus cold-worked and as-welded product.
Reference datasheet — S44635 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Annealed condition
S44635 tempers and conditions
S44635 is supplied in 3 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
autogenous or filler weld without post-weld anneal | Field/fabrication condition; expect reduced HAZ toughness and slightly lower pitting resistance unless interstitials are strictly controlled. | 490 | 660 | 20 | 18 HRC | 2.2 % IACS |
AnnealedDefault solution annealed and quenched (plate/sheet/bar) | Standard supply condition for plate, sheet and bar; best corrosion resistance and toughness. | 500 | 680 | 27 | 16 HRC | 2.2 % IACS |
cold drawn / cold rolled, not re-annealed | Choose when higher strength and tighter dimensional tolerance are needed and severe crevice-corrosion service is not the driver. | 650 | 790 | 15 | 24 HRC | 2.2 % IACS |
Supply forms, finishes and certifications
Ways S44635 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Annealed Tube | Seamless or welded-and-annealed tubing | Supply form |
What is S44635?
S44635 (MONIT) is a 25Cr-4Mo-4Ni super-ferritic stainless steel in which nickel is added for toughness, supplied as annealed sheet, plate and tube plus cold-worked and as-welded product. It is used for high resistance to chloride pitting and crevice corrosion in seawater, with 500 MPa yield, 680 MPa tensile, 27 % elongation and 210 HB in the annealed condition. Service is limited to about 300 °C, welding must be low heat input with full back-purge, and thick sections risk HAZ embrittlement; cost and availability are both restrictive. S44660 is the nearest substitute. S44635 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F). S44635 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 77% of stainless steel grades. Elongation at break is 27% and the elastic modulus is 205 GPa (29.7 Msi).
What is S44635 used for?
- seawater heat exchangers
- desalination equipment
- offshore piping
Advantages
- Good corrosion resistance — 80/100, better than 88% of stainless steel grades
- High strength — 500 MPa (72.5 ksi), better than 77% of stainless steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
- Low fracture toughness — 80 MPa·√m (72.8 ksi·√in), worse than 79% of stainless steel grades
S44635 properties
Typical room-temperature values for S44635-Annealed; bars are the position among stainless steel grades.
Physical3
S44635 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F).
Mechanical17
S44635 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 77% of stainless steel grades. Elongation at break is 27% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal5
S44635 is rated for continuous service to 300°C (572 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
S44635 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 88% of stainless steel grades.
Sustainability4
Producing a kilogram of S44635 takes about 62 MJ of energy and emits 5.4 kg of CO₂ — more than 75% of stainless steel grades. Typical recycled content is 55%.
Manufacturability6
S44635's machinability is fair (42/100, better than 79% of stainless steel grades); weldability good (55/100); formability good (55/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. S44635 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S44635
Is S44635 easy to machine?
Machines similar to 26-1 ferritics — rigid setup, sharp positive-rake carbide, moderate speed and heavy positive feed to avoid work-hardened glazing; better chip control than 316L.
Can S44635 be welded?
Weldable by GTAW/PAW with very low heat input, high-purity argon (with He) shielding and full back-purge; use matched or Ni-base filler and keep interstitial pickup minimal, no preheat, no PWHT above 300 °C.
Can S44635 be formed, bent or molded?
Cold formable in thin gauge with generous bend radii (≥2t) and springback allowance; hot work 900–1100 °C followed by anneal at ~1000–1050 °C with rapid cooling.
S44635 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CC+N ≤ 0.045 | ≤ 0.03 | 0.02 |
| NC+N ≤ 0.045 | ≤ 0.04 | 0.02 |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 0.75 | 0.4 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0 |
| Cr | 24.5 – 26 | 25 |
| Ni | 3.5 – 4.5 | 4 |
| Mo | 3.5 – 4.5 | 4 |
| Ti+Nbmin 0.20 + 4(C+N); stabilizers | 0.2 – 0.8 | 0.4 |
| Fe | balance |
What surface finishes work on S44635?
Pickle and passivate in HNO3-HF after welding to restore the chromium oxide film; polishes to a bright finish and does not anodize (n/a for stainless).
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel S44635 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- MONIT
How much does S44635 cost?
S44635 is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S44635 — frequently asked
What is S44635 used for?
S44635 is typically used for seawater heat exchangers, desalination equipment and offshore piping. In short: nickel-toughened super-ferritic; 500 MPa yield ferritic; seawater crevice resistance.
What is the yield strength of S44635?
S44635 has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 77% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is S44635 easy to machine?
Not especially — machinability is rated fair (42/100, better than 79% of stainless steel grades). Machines similar to 26-1 ferritics — rigid setup, sharp positive-rake carbide, moderate speed and heavy positive feed to avoid work-hardened glazing; better chip control than 316L.
Can S44635 be welded?
Yes — weldability is rated good (55/100). Weldable by GTAW/PAW with very low heat input, high-purity argon (with He) shielding and full back-purge; use matched or Ni-base filler and keep interstitial pickup minimal, no preheat, no PWHT above 300 °C.
What surface finishes work on S44635?
Pickle and passivate in HNO3-HF after welding to restore the chromium oxide film; polishes to a bright finish and does not anodize (n/a for stainless).
Can S44635 be formed, bent or molded?
Cold formable in thin gauge with generous bend radii (≥2t) and springback allowance; hot work 900–1100 °C followed by anneal at ~1000–1050 °C with rapid cooling.
What is the maximum service temperature of S44635?
S44635 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does S44635 cost?
S44635 is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2023)
- ASTM A268/A268M — Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing — ASTM International (2022)
- UNS S44635 alloy designation (SAE/ASTM DS-56 Metals & Alloys in the Unified Numbering System) — SAE International / ASTM (2017)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (superferritic stainless steels) — ASM International (1990)
- MONIT 25-4-4 superferritic stainless steel datasheet — Nyby / Outokumpu lineage (2010)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.