Stainless Steel 317LN-3/4 Hard
Supply condition
AISI/SAE 317LN · UNS S31753
3/4 Hard = three-quarter hard
Flat parts and clips requiring very high yield with essentially no forming.
Values for the 3/4 Hard condition
Other 317LN tempers and conditions
317LN is listed in 7 conditions; see the grade overview at 317LN.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault solution annealed and quenched (1040–1120 °C, rapid cool) | Standard stocked condition for plate, sheet, pipe and bar; maximum corrosion resistance and ductility. | 320 | 620 | 48 | 170 HB | — |
autogenous/filler weld metal and HAZ, no post-weld anneal | Represents fabricated weldments; low carbon and N keep sensitisation risk low but weld metal ferrite/δ affects toughness. | 330 | 600 | 35 | 185 HB | 2.2 % IACS |
annealed then cold drawn bar/wire (light draft) | Choose for straight, close-tolerance bar with a strength bump over annealed; slightly reduced ductility. | 500 | 720 | 30 | 18 HRC | 2.2 % IACS |
Quarter hard | Light cold-rolled strip/sheet where extra yield strength is needed but some bending is still required. | 620 | 900 | 20 | 25 HRC | 2.2 % IACS |
Half hard | Structural strip/sheet needing high yield with only mild forming; springback and magnetic permeability rise. | 790 | 1,035 | 12 | 32 HRC | 2.2 % IACS |
3/4 HardThis page Three-quarter hard | Flat parts and clips requiring very high yield with essentially no forming. | 930 | 1,170 | 8 | 36 HRC | 2.2 % IACS |
heavily cold rolled strip | Maximum strength thin strip for shims and flat springs; not formable, most magnetic condition. | 1,000 | 1,280 | 6 | 40 HRC | 2.2 % IACS |
What is 317LN-3/4 Hard?
317LN-3/4 Hard is 317LN supplied in the 3/4 Hard condition — flat parts and clips requiring very high yield with essentially no forming. 317LN-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 8% and the elastic modulus is 200 GPa (29 Msi). 317LN-3/4 Hard has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,375°C (2,507 °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
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
- Good corrosion resistance — 74/100, better than 78% of stainless steel grades
Limitations
- Limited ductility — 8%, worse than 99% of stainless steel grades
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
- Limited formability — 20/100, worse than 86% of stainless steel grades
317LN-3/4 Hard properties
Typical room-temperature values for 317LN-3/4 Hard; 23 are specific to this condition. Other listed values are 317LN reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
317LN-3/4 Hard has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,375°C (2,507 °F).
Mechanical16
317LN-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 8% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
317LN-3/4 Hard is rated for continuous service to 300°C (572 °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
317LN-3/4 Hard conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (74/100), better than 78% of stainless steel grades.
Sustainability4
Producing a kilogram of 317LN-3/4 Hard takes about 60 MJ of energy and emits 4.5 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 65%.
Manufacturability8
317LN-3/4 Hard's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability good (65/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 317LN-3/4 Hard
Is 317LN easy to machine?
Gummy and strongly work-hardening — use rigid setups, positive-rake carbide, heavy positive feed, 20–35 % lower speeds than 304 and flood coolant.
Can 317LN be welded?
Excellent with GTAW/GMAW/SMAW using 317L/317LMn or overalloyed 625-type filler; keep heat input low, interpass <150 °C, no post-weld anneal needed for corrosion service.
Can 317LN be formed, bent or molded?
Cold forms well but nitrogen raises yield and springback versus 317L — allow higher press tonnage and generous bend radii; hot work 1150–1200 °C then solution anneal and water quench.
What surface finishes work on 317LN?
Pickle and passivate (ASTM A967) or electropolish after fabrication to restore the passive film; not anodizable, polishes to No.4/mirror finishes.
317LN 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 for intergranular corrosion resistance | ≤ 0.03 | 0.02 |
| Mn | ≤ 2 | 1.5 |
| Si | ≤ 0.75 | 0.5 |
| P | ≤ 0.05 | 0.03 |
| S | ≤ 0.03 | 0 |
| Cr | 18 – 20 | 18.7 |
| Ni | 11 – 15 | 13 |
| Mo | 3 – 4 | 3.3 |
| Nsolid-solution strengthening + pitting resistance | 0.1 – 0.22 | 0.15 |
| Fe | balance | — |
317LN-3/4 Hard — frequently asked
What is 317LN-3/4 Hard used for?
317LN-3/4 Hard is typically used for chemical processing, pressure vessels and pulp and paper equipment. In short: higher-strength 317L; no post-weld anneal needed; nitrogen-boosted pitting resistance.
What is the yield strength of 317LN-3/4 Hard?
317LN-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 317LN-3/4 Hard easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Gummy and strongly work-hardening — use rigid setups, positive-rake carbide, heavy positive feed, 20–35 % lower speeds than 304 and flood coolant.
Can 317LN-3/4 Hard be welded?
Yes — weldability is rated good (65/100). Excellent with GTAW/GMAW/SMAW using 317L/317LMn or overalloyed 625-type filler; keep heat input low, interpass <150 °C, no post-weld anneal needed for corrosion service.
What surface finishes work on 317LN-3/4 Hard?
Pickle and passivate (ASTM A967) or electropolish after fabrication to restore the passive film; not anodizable, polishes to No.4/mirror finishes.
Can 317LN-3/4 Hard be formed, bent or molded?
Cold forms well but nitrogen raises yield and springback versus 317L — allow higher press tonnage and generous bend radii; hot work 1150–1200 °C then solution anneal and water quench.
What is the maximum service temperature of 317LN-3/4 Hard?
317LN-3/4 Hard 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.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip — ASTM International (2023)
- ASTM A312/A312M — Seamless and Welded Austenitic Stainless Steel Pipes (TP317LN) — ASTM International (2022)
- ASTM A666 — Annealed or Cold-Worked Austenitic Stainless Steel Sheet, Strip, Plate and Flat Bar — ASTM International (2015)
- GB/T 24511 / GB/T 4237 — SAC (2017)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Austenitic stainless 317L/317LN data sheets — Outokumpu / Sandvik (2021)
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.