Steel 1050 · heat-treated state
Steel 1050 QT-315
Properties of the QT-315 condition, compared with the other 1050 tempers.
High-strength wear condition with slightly better ductility than the 205 °C temper.
What is 1050 QT-315?
1050 QT-315 is 1050 heat treated to QT-315 — high-strength wear condition with slightly better ductility than the 205 °C temper. 1050 QT-315 has a yield strength of 793 MPa (115 ksi) and a tensile strength of 1,090 MPa (158 ksi) — stronger than 86% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi). 1050 QT-315 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). HR is the default condition FabDigit quotes; QT-315 is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High electrical conductivity — 10.5 % IACS, better than 89% of steel grades
- High strength — 793 MPa (115 ksi), better than 86% of steel grades
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
Limitations
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 83% of steel grades
- Limited service temperature — 260°C (500 °F), worse than 81% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
1050 QT-315 properties
Typical room-temperature values for 1050 QT-315 — 10 properties are specific to this condition; the rest are grade-level values shared by every 1050 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
1050 QT-315 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical14
1050 QT-315 has a yield strength of 793 MPa (115 ksi) and a tensile strength of 1,090 MPa (158 ksi) — stronger than 86% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
1050 QT-315 is rated for continuous service to 260°C (500 °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
1050 QT-315 conducts electricity at 10.5 % IACS, better than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of 1050 QT-315 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
1050 QT-315's machinability is fair (48/100, worse than 57% of steel grades); weldability poor (30/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 1050 tempers and conditions
1050 is also supplied in 11 other conditions. The full side-by-side table is on the 1050 overview.
- HRDefaultDefault stock condition for 50#/S50C bar and plate that will be machined and then quench- or induction-hardened.340 MPa yield · 179 HB
- QT-205Maximum hardness and wear resistance for small sections (blades, wear plates); low toughness.807 MPa yield · 51 HRC
- QT-315High-strength wear condition with slightly better ductility than the 205 °C temper.793 MPa yield · 45 HRC
- QT-425Balanced strength/toughness for shafts, gears and highly loaded machine parts.717 MPa yield · 40 HRC
- QT-540Use the water-quenched, 540 °C tempered condition at 26–30 HRC for shafts and couplings needing 862 MPa tensile with good toughness while remaining machinable.655 MPa yield · 27 HRC
- IHPick for shafts, gear teeth and guide rails needing a 55–60 HRC wear skin on a tough core.620 MPa yield · 58 HRC
- CDChoose for straight, close-tolerance shafting with a better surface and higher yield than hot rolled.580 MPa yield · 197 HB
- QT-650Softest quench-and-temper option — maximum toughness and machinability with moderate strength.538 MPa yield · 20 HRC
- NUniform fine pearlitic structure — best base condition for plate, forgings and pre-machining stability.427 MPa yield · 217 HB
- AnnealedPick for maximum machinability/formability before hardening, or for stress-free blanks.365 MPa yield · 187 HB
Working with 1050 QT-315
Is 1050 easy to machine?
Machine in the annealed or ≤30 HRC tempered state with carbide tooling and rigid setups; expect ~50 % of 1212 speeds and use chip breakers as it is not free-cutting.
Can 1050 be welded?
Poor weldability at 0.5 % C — preheat 200–300 °C, low-hydrogen consumables, control interpass and post-weld temper/stress-relieve to avoid HAZ cracking.
Can 1050 be formed, bent or molded?
Cold form only in annealed or spheroidized condition with generous bend radii (≥2t); hot forge 1100–1200 °C and normalize afterwards.
What surface finishes work on 1050?
No inherent corrosion resistance — oil, phosphate, black oxide, zinc or hard chrome plate; hardened surfaces grind and polish well for die and shaft applications.
1050 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 |
|---|---|---|
| CJIS S50C: 0.47–0.53 | 0.48 – 0.55 | 0.5 |
| Mn | 0.6 – 0.9 | 0.75 |
| SiNot specified in SAE 1050 (silicon-killed practice); required by JIS S50C / DIN C50 | 0.15 – 0.35 | 0.25 |
| P0.030 max for S50C / C50 | ≤ 0.04 | — |
| S0.035 max for S50C / C50 | ≤ 0.05 | — |
| CrResidual limit (JIS/DIN) | ≤ 0.2 | — |
| NiResidual limit | ≤ 0.2 | — |
| CuResidual limit | ≤ 0.3 | — |
| Fe | balance | — |
1050 QT-315 — frequently asked
What is 1050 QT-315 used for?
1050 QT-315 is typically used for forged gears, shafts and hand tools. In short: hard; high-carbon spring steel.
What is the yield strength of 1050 QT-315?
1050 QT-315 has a typical yield strength of 793 MPa (115 ksi) and a tensile strength of 1,090 MPa (158 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 1050 QT-315 easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Machine in the annealed or ≤30 HRC tempered state with carbide tooling and rigid setups; expect ~50 % of 1212 speeds and use chip breakers as it is not free-cutting.
Can 1050 QT-315 be welded?
Not readily — weldability is rated poor (30/100). Poor weldability at 0.5 % C — preheat 200–300 °C, low-hydrogen consumables, control interpass and post-weld temper/stress-relieve to avoid HAZ cracking.
What surface finishes work on 1050 QT-315?
No inherent corrosion resistance — oil, phosphate, black oxide, zinc or hard chrome plate; hardened surfaces grind and polish well for die and shaft applications.
Can 1050 QT-315 be formed, bent or molded?
Cold form only in annealed or spheroidized condition with generous bend radii (≥2t); hot forge 1100–1200 °C and normalize afterwards.
What is the maximum service temperature of 1050 QT-315?
1050 QT-315 is rated for continuous use to about 260°C (500 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1050-HR and 1050 QT-205?
HR is the default condition — default stock condition for 50#/S50C bar and plate that will be machined and then quench- or induction-hardened. QT-205: maximum hardness and wear resistance for small sections (blades, wear plates); low toughness. Yield strength is 340 MPa in HR versus 807 MPa in QT-205.
Can FabDigit make parts in 1050 QT-315?
Yes — 1050 QT-315 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- JIS G4051 — Carbon steels for machine structural use (S50C) — JSA (2016)
- EN 10083-2 / DIN C50 (1.0540) — CEN (2006)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook (machinability ratings) — Industrial Press (2020)
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.