Stainless Steel S21603-3/4 Hard
Supply condition
UNS S21603 · AISI/SAE XM-18
3/4 Hard = three-quarter hard
High-strength strip/wire temper where forming is limited to gentle bends.
Values for the 3/4 Hard condition
Other S21603 tempers and conditions
S21603 is listed in 7 conditions; see the grade overview at S21603.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault Annealed (solution annealed ~1065–1120 °C, water quenched) | Standard stocked condition for plate, sheet, bar and forgings; best corrosion resistance, weldability and formability. | 450 | 760 | 48 | 200 HB | — |
Hot worked / as-forged (not solution annealed) | As-forged or hot-rolled bar supplied for subsequent machining and annealing; corrosion performance not guaranteed until solution treated. | 500 | 800 | 38 | 20 HRC | 2 % IACS |
Cold Drawn / cold finished bar (light cold work) | Choose for straight, close-tolerance bar with a modest strength bump over annealed; typical for shafts and fasteners stock. | 690 | 900 | 25 | 25 HRC | 2 % IACS |
Quarter hard | Light temper rolling for sheet/strip and high-strength fasteners where some bend ductility is still needed. | 690 | 900 | 25 | 25 HRC | 2 % IACS |
Half hard | Mid temper for springy strip, clamps and high-load non-magnetic fittings. | 790 | 1,035 | 15 | 30 HRC | 2 % IACS |
3/4 HardThis page Three-quarter hard | High-strength strip/wire temper where forming is limited to gentle bends. | 930 | 1,170 | 12 | 35 HRC | 2 % IACS |
Cold worked, Full Hard (strain hardened) | Maximum strength strip/wire for springs and high-tensile non-magnetic parts; essentially no cold formability and reduced SCC margin. | 1,030 | 1,280 | 8 | 39 HRC | 2 % IACS |
What is S21603-3/4 Hard?
S21603-3/4 Hard is S21603 supplied in the 3/4 Hard condition — high-strength strip/wire temper where forming is limited to gentle bends. S21603-3/4 Hard has a yield strength of 930 MPa (135 ksi) and a tensile strength of 1,170 MPa (170 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi). S21603-3/4 Hard has a density of 7.81 g/cm³ (0.282 lb/in³), heavier than 57% of stainless steel grades. It melts at 1,370°C (2,498 °F). Annealed is the default condition FabDigit quotes; 3/4 Hard is available on request or by drawing note.
Advantages
- High strength — 930 MPa (135 ksi), better than 98% of stainless steel grades
Limitations
- Limited ductility — 12%, worse than 95% of stainless steel grades
- Limited formability — 22/100, worse than 82% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
- Low electrical conductivity — 2 % IACS, worse than 77% of stainless steel grades
S21603-3/4 Hard properties
Typical room-temperature values for S21603-3/4 Hard; 22 are specific to this condition. Other listed values are S21603 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
S21603-3/4 Hard has a density of 7.81 g/cm³ (0.282 lb/in³), heavier than 57% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical14
S21603-3/4 Hard has a yield strength of 930 MPa (135 ksi) and a tensile strength of 1,170 MPa (170 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
S21603-3/4 Hard is rated for continuous service to 400°C (752 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), worse than 72% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
S21603-3/4 Hard conducts electricity at 2 % IACS, worse than 77% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 56% of stainless steel grades.
Sustainability4
Producing a kilogram of S21603-3/4 Hard takes about 70 MJ of energy and emits 5 kg of CO₂ — more than 81% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
S21603-3/4 Hard's machinability is poor (27/100, worse than 83% of stainless steel grades); weldability good (62/100); formability poor (22/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S21603-3/4 Hard
Is S21603 easy to machine?
Treat as a difficult austenitic: rigid setups, positive-rake sharp carbide, heavy feeds and flood coolant to cut under the work-hardened skin; expect ~30 % of 1212 speeds.
Can S21603 be welded?
Readily welded by GTAW/GMAW without pre- or post-heat using over-alloyed filler (ER209, ER240 or ER316L for lower strength); ≤0.03 % C avoids sensitization, keep interpass below ~150 °C.
Can S21603 be formed, bent or molded?
Cold forms well but work-hardens fast — use larger bend radii, extra press tonnage and interstage solution anneals at 1065–1120 °C with rapid quench; hot work 1150–1230 °C, finish above 950 °C.
What surface finishes work on S21603?
Passivate per ASTM A967 or electropolish after fabrication; not anodizable, and pickling should use nitric-hydrofluoric baths sized for the high-Mn scale.
S21603 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 |
|---|---|---|
| Clow-carbon version of S21600 | ≤ 0.03 | 0.02 |
| Mn | 7.5 – 9 | 8.3 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.05 | — |
| S | ≤ 0.03 | — |
| Cr | 17.5 – 22 | 20 |
| Ni | 5 – 7 | 6 |
| Mo | 2 – 3 | 2.5 |
| Nprimary strengthener | 0.25 – 0.5 | 0.35 |
| Fe | balance | — |
S21603-3/4 Hard — frequently asked
What is S21603-3/4 Hard used for?
S21603-3/4 Hard is typically used for welded structural components, pressure vessels and fasteners. In short: weldable version of XM-17; low-carbon high-strength austenitic; no post-weld heat treatment.
What is the yield strength of S21603-3/4 Hard?
S21603-3/4 Hard has a typical yield strength of 930 MPa (135 ksi) and a tensile strength of 1,170 MPa (170 ksi) — stronger than 98% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is S21603-3/4 Hard easy to machine?
Not especially — machinability is rated poor (27/100, worse than 83% of stainless steel grades). Treat as a difficult austenitic: rigid setups, positive-rake sharp carbide, heavy feeds and flood coolant to cut under the work-hardened skin; expect ~30 % of 1212 speeds.
Can S21603-3/4 Hard be welded?
Yes — weldability is rated good (62/100). Readily welded by GTAW/GMAW without pre- or post-heat using over-alloyed filler (ER209, ER240 or ER316L for lower strength); ≤0.03 % C avoids sensitization, keep interpass below ~150 °C.
What surface finishes work on S21603-3/4 Hard?
Passivate per ASTM A967 or electropolish after fabrication; not anodizable, and pickling should use nitric-hydrofluoric baths sized for the high-Mn scale.
Can S21603-3/4 Hard be formed, bent or molded?
Cold forms well but work-hardens fast — use larger bend radii, extra press tonnage and interstage solution anneals at 1065–1120 °C with rapid quench; hot work 1150–1230 °C, finish above 950 °C.
What is the maximum service temperature of S21603-3/4 Hard?
S21603-3/4 Hard is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip — ASTM International (2023)
- ASTM A276/A276M — Stainless Steel Bars and Shapes — ASTM International (2023)
- SAE/ASTM DS-56 (UNS) Metals & Alloys in the Unified Numbering System — S21600/S21603 — SAE International / ASTM (2017)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
- Nitrogen-strengthened Cr-Mn austenitic stainless product data (216/21-6-9 family) — Specialty stainless producers (2022)
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.