Steel 1139
AISI/SAE 1139 · UNS G11390
1139 (UNS G11390) is a medium-carbon resulfurized free-machining steel comparable to 1137 and 1140, using manganese sulfides for chip breaking with about 0.40 % carbon for heat-treat response.
Reference datasheet — 1139 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 CD condition
1139 tempers and conditions
1139 is supplied in 9 conditions, soft to hard. CD is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot rolled | Lowest-cost form for parts that will be fully machined or later heat treated. | 345 | 620 | 16 | 11 HRC | 10 % IACS |
Annealed | Softest condition, used before severe machining or when maximum dimensional stability matters. | 345 | 570 | 22 | 8 HRC | 10.5 % IACS |
Normalized | Refines forging/rolling structure and gives uniform mid-range strength before final machining. | 380 | 655 | 20 | 11 HRC | 10 % IACS |
Cold Drawn, Stress Relieved | Choose when heavy asymmetric machining would otherwise cause the part to bow. | 530 | 640 | 14 | 10 HRC | 10 % IACS |
CDDefault Cold drawn | Standard stocked condition: best size tolerance, straightness and chip control for screw-machine work. | 565 | 655 | 12 | 192 HB | — |
Induction hardened | Pick for wear surfaces and bearing journals where the machined core toughness is retained. | 570 | 700 | 11 | 54 HRC | 9.5 % IACS |
oil quenched from ~845 °C, tempered high | Tough, readily machinable strength level for shafts and studs with moderate loading. | 660 | 830 | 17 | 24 HRC | 9.5 % IACS |
oil quenched, tempered ~540 °C | Common through-hardened level for higher-load shafts, pins and threaded fasteners. | 780 | 950 | 15 | 30 HRC | — |
oil quenched, tempered ~455 °C | Highest practical through-hardened level; accept reduced toughness and machinability. | 930 | 1,120 | 12 | 36 HRC | 9 % IACS |
What is 1139?
1139 (UNS G11390) is a medium-carbon resulfurized free-machining steel comparable to 1137 and 1140, using manganese sulfides for chip breaking with about 0.40 % carbon for heat-treat response. It is used for turned shafts, studs and bolts at roughly 565 MPa yield, 655 MPa tensile, 12 % elongation, 192 HB (92 HRB) and a machinability score of 72, and is stocked hot-rolled, cold-drawn, annealed, normalized, induction-hardened or quenched and tempered to 22–38 HRC. Weldability and cold formability are poor (formability 30) and there is no corrosion resistance. Use 1141 or 1144 for similar turned work, 1045 where welding is required. 1139 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). 1139 has a yield strength of 565 MPa (81.9 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 73% of steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi).
What is 1139 used for?
- Shafts
- Studs
- Bolts
Advantages
- Easy to machine — 72/100, better than 97% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
1139 properties
Typical room-temperature values for 1139-CD; bars are the position among steel grades.
Physical3
1139 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical13
1139 has a yield strength of 565 MPa (81.9 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 73% of steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1139 is rated for continuous service to 400°C (752 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
1139 conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 1139 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
1139's machinability is very good (72/100, better than 97% of steel grades); weldability poor (30/100); formability poor (30/100).
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 steel family
Yield strength against density for every steel grade FabDigit runs. 1139 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 1139
Is 1139 easy to machine?
Excellent chip breaking from MnS; run 20–30% higher surface speed than 1045, carbide inserts, positive rake, light sulfurized oil or coolant.
Can 1139 be welded?
Not recommended for structural welds — high S plus ~0.40 C promotes hot cracking and hard HAZ; if welded, preheat 200–300 °C, low-hydrogen consumables and post-weld stress relief.
Can 1139 be formed, bent or molded?
Poor cold formability, especially transverse; hot forge 1150–1230 °C and finish above 900 °C, then normalize.
1139 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 |
|---|---|---|
| CSAE J403 / ASTM A29 heat analysis | 0.35 – 0.43 | 0.39 |
| Mn | 1.35 – 1.65 | 1.5 |
| P | ≤ 0.04 | 0.02 |
| Sresulfurized for machinability | 0.13 – 0.2 | 0.16 |
| Sinot normally specified for resulfurized grades | ≤ 0.1 | 0.05 |
| Fe | balance |
What surface finishes work on 1139?
No anodizing; protect with zinc or zinc-nickel plating, black oxide, phosphate-and-oil, or paint. Sulfide stringers limit mirror polish and can leave micro-pits after plating.
Surface treatments FabDigit runs on 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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 1139 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G11390
How much does 1139 cost?
1139 is a budget-cost steel ($), cheaper than about 90% 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.
1139 — frequently asked
What is 1139 used for?
1139 is typically used for shafts, studs and bolts. In short: free-machining 1140 equivalent; heat-treatable to 38 HRC; poor weldability by design.
What is the yield strength of 1139?
1139 has a typical yield strength of 565 MPa (81.9 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 1139 easy to machine?
Yes — machinability is rated very good (72/100, better than 97% of steel grades). Excellent chip breaking from MnS; run 20–30% higher surface speed than 1045, carbide inserts, positive rake, light sulfurized oil or coolant.
Can 1139 be welded?
Not readily — weldability is rated poor (30/100). Not recommended for structural welds — high S plus ~0.40 C promotes hot cracking and hard HAZ; if welded, preheat 200–300 °C, low-hydrogen consumables and post-weld stress relief.
What surface finishes work on 1139?
No anodizing; protect with zinc or zinc-nickel plating, black oxide, phosphate-and-oil, or paint. Sulfide stringers limit mirror polish and can leave micro-pits after plating.
Can 1139 be formed, bent or molded?
Poor cold formability, especially transverse; hot forge 1150–1230 °C and finish above 900 °C, then normalize.
What is the maximum service temperature of 1139?
1139 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.
What is the difference between 1139-CD and 1139-HR?
CD is the default condition — standard stocked condition: best size tolerance, straightness and chip control for screw-machine work. HR: lowest-cost form for parts that will be fully machined or later heat treated. Yield strength is 565 MPa in CD versus 345 MPa in HR.
How much does 1139 cost?
1139 is a budget-cost steel ($), cheaper than about 90% 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
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
- ASTM A108 — Steel Bar, Carbon and Alloy, Cold-Finished — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- GB/T 8731 (Y40Mn comparable grade) — SAC (2008)
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.