Stainless Steel XM-21-FH (Full hard)
Supply condition
UNS S30452
Maximum strength flat product for blanked, non-formed parts; very limited ductility and higher magnetic permeability.
Values for the FH condition
Other XM-21 tempers and conditions
XM-21 is listed in 6 conditions; see the grade overview at XM-21.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault solution annealed (1040–1120 °C, water quenched) | Standard stocked condition for plate, sheet, bar and tube; best corrosion resistance, ductility and weldability. | 400 | 690 | 48 | 200 HB | — |
Cold drawn | Choose for straight, close-tolerance bar with higher yield strength than annealed; retains good ductility. | 600 | 790 | 25 | 21 HRC | 2.4 % IACS |
Quarter hard | Sheet/strip temper for moderate strength increase while still allowing bending and mild forming. | 650 | 900 | 18 | 25 HRC | 2.4 % IACS |
Half hard | Use where high strength with limited bending is needed, e.g. structural strip, clamps and springs-of-convenience. | 800 | 1,060 | 12 | 32 HRC | 2.4 % IACS |
Three-quarter hard | Near-maximum strength strip for flat parts formed only by shallow bends or blanking. | 960 | 1,230 | 8 | 37 HRC | 2.4 % IACS |
FHThis page Full hard | Maximum strength flat product for blanked, non-formed parts; very limited ductility and higher magnetic permeability. | 1,000 | 1,310 | 5 | 41 HRC | 2.4 % IACS |
What is XM-21-FH?
XM-21-FH is XM-21 supplied in the FH condition — maximum strength flat product for blanked, non-formed parts; very limited ductility and higher magnetic permeability. XM-21-FH has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,310 MPa (190 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 193 GPa (28 Msi). XM-21-FH has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; FH is available on request or by drawing note.
Advantages
- High strength — 1,000 MPa (145 ksi), better than 98% of stainless steel grades
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
Limitations
- Limited ductility — 5%, worse than 100% of stainless steel grades
- Difficult to machine — 22/100, worse than 95% of stainless steel grades
- Limited formability — 12/100, worse than 93% of stainless steel grades
- Limited service temperature — 315°C (599 °F), worse than 85% of stainless steel grades
XM-21-FH properties
Typical room-temperature values for XM-21-FH; 23 are specific to this condition. Other listed values are XM-21 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
XM-21-FH has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical14
XM-21-FH has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,310 MPa (190 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
XM-21-FH is rated for continuous service to 315°C (599 °F). It conducts heat at 16.2 W/m·K (9.36 BTU/hr·ft·°F), better than 64% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
XM-21-FH conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of XM-21-FH takes about 53 MJ of energy and emits 4.5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 70%.
Manufacturability8
XM-21-FH's machinability is poor (22/100, worse than 95% of stainless steel grades); weldability good (60/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with XM-21-FH
Is XM-21 easy to machine?
Machines like 304 but work-hardens faster due to nitrogen — use rigid setups, positive-rake sharp carbide, heavy feed, no dwell, and flood coolant.
Can XM-21 be welded?
Readily welded by GTAW/GMAW/SMAW without preheat; use 308L/309L or high-nitrogen filler, keep interpass below ~150 °C and limit heat input to preserve the nitrogen strength benefit.
Can XM-21 be formed, bent or molded?
Cold forms and deep draws similar to 304 but needs roughly 20–30 % higher press loads and larger bend radii; hot work at 1150–1200 °C followed by solution anneal.
What surface finishes work on XM-21?
Not anodizable; pickle and passivate per ASTM A967, or electropolish/mechanically polish to No.4–No.8 finish for hygienic and decorative service.
XM-21 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 |
|---|---|---|
| C | ≤ 0.08 | 0.05 |
| Mn | ≤ 2 | 1.6 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.05 | 0.03 |
| S | ≤ 0.03 | 0.01 |
| Cr | 18 – 20 | 19 |
| Ni | 8 – 10.5 | 9 |
| Nnitrogen strengthening — the defining addition vs Type 304 | 0.16 – 0.3 | 0.22 |
| Fe | balance | — |
XM-21-FH — frequently asked
What is XM-21-FH used for?
XM-21-FH is typically used for cryogenic storage vessels, structural pressure equipment, pressure vessel shells and heads, cryogenic piping and transfer lines, chemical process tanks and tank trailer and railcar bodies. In short: nitrogen-strengthened 304; higher yield than 304; retains 304 weldability.
What is the yield strength of XM-21-FH?
XM-21-FH has a typical yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,310 MPa (190 ksi) — stronger than 98% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is XM-21-FH easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of stainless steel grades). Machines like 304 but work-hardens faster due to nitrogen — use rigid setups, positive-rake sharp carbide, heavy feed, no dwell, and flood coolant.
Can XM-21-FH be welded?
Yes — weldability is rated good (60/100). Readily welded by GTAW/GMAW/SMAW without preheat; use 308L/309L or high-nitrogen filler, keep interpass below ~150 °C and limit heat input to preserve the nitrogen strength benefit.
What surface finishes work on XM-21-FH?
Not anodizable; pickle and passivate per ASTM A967, or electropolish/mechanically polish to No.4–No.8 finish for hygienic and decorative service.
Can XM-21-FH be formed, bent or molded?
Cold forms and deep draws similar to 304 but needs roughly 20–30 % higher press loads and larger bend radii; hot work at 1150–1200 °C followed by solution anneal.
What is the maximum service temperature of XM-21-FH?
XM-21-FH is rated for continuous use to about 315°C (599 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between XM-21 Annealed and XM-21-FH?
Annealed is the default condition — standard stocked condition for plate, sheet, bar and tube; best corrosion resistance, ductility and weldability. FH: maximum strength flat product for blanked, non-formed parts; very limited ductility and higher magnetic permeability. Yield strength is 400 MPa in Annealed versus 1,000 MPa in FH.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip (UNS S30452, XM-21) — ASTM International (2023)
- ASTM A276/A479 — Stainless Steel Bars and Shapes — ASTM International (2022)
- ASTM A666 — Annealed or Cold-Worked Austenitic Stainless Steel Sheet, Strip, Plate and Flat Bar — ASTM International (2015)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- SAE J405 / UNS S30452 chemical composition listing — SAE International (2013)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.