Stainless Steel XM-21 Annealed
Temper · default condition
UNS S30452
Standard stocked condition for plate, sheet, bar and tube; best corrosion resistance, ductility and weldability.
Values for the Annealed 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 |
|---|---|---|---|---|---|---|
AnnealedDefaultThis page 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 |
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 Annealed?
XM-21 Annealed is XM-21 in the Annealed temper — standard stocked condition for plate, sheet, bar and tube; best corrosion resistance, ductility and weldability. XM-21 Annealed has a yield strength of 400 MPa (58 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 48% and the elastic modulus is 195 GPa (28.3 Msi). XM-21 Annealed 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).
Advantages
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
- Readily welded — 85/100, better than 87% of stainless steel grades
- Ductile — tolerates forming and impact — 48%, better than 85% of stainless steel grades
- Forms and bends easily — 70/100, better than 79% of stainless steel grades
XM-21 Annealed properties
Typical room-temperature values for XM-21 Annealed; 12 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 Annealed 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 Annealed has a yield strength of 400 MPa (58 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 48% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
XM-21 Annealed is rated for continuous service to 800°C (1,472 °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 Annealed conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 68% of stainless steel grades.
Sustainability4
Producing a kilogram of XM-21 Annealed 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 Annealed's machinability is fair (35/100, better than 51% of stainless steel grades); weldability excellent (85/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with XM-21 Annealed
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 Annealed — frequently asked
What is XM-21 Annealed used for?
XM-21 Annealed 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 Annealed?
XM-21 Annealed has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 57% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is XM-21 Annealed easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% 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 Annealed be welded?
Yes — weldability is rated excellent (85/100). 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 Annealed?
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 Annealed 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 Annealed?
XM-21 Annealed is rated for continuous use to about 800°C (1,472 °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.