Steel 35SiMn QT-SPRING
Heat-treated state
GB 35SiMn
Choose for flat springs, spring washers and elastic clamps exploiting the high silicon elastic limit.
Values for the QT-SPRING condition
Other 35SiMn tempers and conditions
35SiMn is listed in 10 conditions; see the grade overview at 35SiMn.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest supply condition (≤229 HBW per GB/T 3077) for deep machining, cold shearing or straightening before final Q&T. | 370 | 640 | 22 | 200 HB | — |
Hot rolled | Cheapest mill condition for stock that will be re-heat-treated after machining or forging. | 470 | 780 | 16 | 235 HB | — |
Normalized | Grain-refining treatment for forgings and for uniform machinability before quench and temper. | 500 | 800 | 17 | 22 HRC | 6 % IACS |
Cold drawn | Bright, size-accurate bar for parts machined to near stock size where no further heat treatment is planned. | 650 | 800 | 10 | 22 HRC | 6 % IACS |
QTDefault Quenched and tempered | Use the standard quenched (900 °C, water) and 570 °C tempered condition for shafts, gears, rods and fasteners; it delivers the 780 MPa yield and 950 MPa tensile values quoted in GB/T 3077. | 780 | 950 | 17 | 30 HRC | — |
tempered ~570–600 °C | Tough general-purpose hardness band for large shafts and machined components needing good impact resistance. | 780 | 950 | 17 | 30 HRC | 6 % IACS |
Induction hardened | Use where a tough Q&T core plus a hard, wear- and fatigue-resistant journal or tooth flank is required. | 780 | 950 | 16 | 52 HRC | 6 % IACS |
tempered ~500–540 °C | Higher-strength temper for heavily loaded rods, spindles and high-strength bolts where some toughness is traded for strength. | 980 | 1,150 | 13 | 36 HRC | — |
tempered ~400–450 °C | High-strength/wear condition for pins, wedges and tooling details; watch temper-embrittlement range and notch sensitivity. | 1,150 | 1,350 | 10 | 42 HRC | — |
QT-SPRINGThis page quenched + tempered 380–430 °C (spring / high-elastic-limit condition) | Choose for flat springs, spring washers and elastic clamps exploiting the high silicon elastic limit. | 1,330 | 1,500 | 8 | 46 HRC | — |
What is 35SiMn QT-SPRING?
35SiMn QT-SPRING is 35SiMn heat treated to QT-SPRING — choose for flat springs, spring washers and elastic clamps exploiting the high silicon elastic limit. 35SiMn QT-SPRING has a yield strength of 1,330 MPa (193 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Elongation at break is 8% and the elastic modulus is 210 GPa (30.5 Msi). 35SiMn QT-SPRING 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). QT is the default condition FabDigit quotes; QT-SPRING is available on request or by drawing note.
Advantages
- High strength — 1,330 MPa (193 ksi), better than 95% of steel grades
Limitations
- Difficult to machine — 20/100, worse than 97% of steel grades
- Limited ductility — 8%, worse than 95% of steel grades
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
- Low electrical conductivity — 6 % IACS, worse than 78% of steel grades
35SiMn QT-SPRING properties
Typical room-temperature values for 35SiMn QT-SPRING; 11 are specific to this condition. Other listed values are 35SiMn reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
35SiMn QT-SPRING 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).
Mechanical16
35SiMn QT-SPRING has a yield strength of 1,330 MPa (193 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Elongation at break is 8% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
35SiMn QT-SPRING is rated for continuous service to 250°C (482 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
35SiMn QT-SPRING conducts electricity at 6 % IACS, worse than 78% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 35SiMn QT-SPRING takes about 26 MJ of energy and emits 2.1 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability8
35SiMn QT-SPRING's machinability is poor (20/100, worse than 97% of steel grades); weldability poor (30/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 35SiMn QT-SPRING
Is 35SiMn easy to machine?
Machine in the annealed (≤229 HBW) or normalised state with carbide tooling; at 30+ HRC use rigid setups, reduced feeds and coolant — silicon makes chips abrasive on tool flanks.
Can 35SiMn be welded?
Poor weldability (CE ≈ 0.8–0.9): preheat 250–350 °C, use low-hydrogen consumables, keep interpass temperature and temper immediately after welding to avoid cold cracking.
Can 35SiMn be formed, bent or molded?
Hot forge/roll 1150 → 850 °C with slow cooling or immediate annealing; cold bending only in the annealed state with generous radii — Q&T material cracks.
What surface finishes work on 35SiMn?
No corrosion resistance: protect with phosphate + oil, black oxide, zinc or Dacromet coating; hard chrome or induction hardening plus grinding for wear surfaces (bake after plating to avoid hydrogen embrittlement).
35SiMn 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 | 0.32 – 0.4 | 0.36 |
| Siprimary strengthening/elastic-limit element | 1.1 – 1.4 | 1.25 |
| Mn | 1.1 – 1.4 | 1.25 |
| Crresidual | ≤ 0.3 | 0.1 |
| Niresidual | ≤ 0.3 | 0.1 |
| Curesidual | ≤ 0.25 | 0.1 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Fe | balance | — |
35SiMn QT-SPRING — frequently asked
What is 35SiMn QT-SPRING used for?
35SiMn QT-SPRING is typically used for shafts, springs and gears. In short: silicon-manganese spring steel; chromium-free hardenable bar; 9260 cross-reference.
What is the yield strength of 35SiMn QT-SPRING?
35SiMn QT-SPRING has a typical yield strength of 1,330 MPa (193 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 35SiMn QT-SPRING easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of steel grades). Machine in the annealed (≤229 HBW) or normalised state with carbide tooling; at 30+ HRC use rigid setups, reduced feeds and coolant — silicon makes chips abrasive on tool flanks.
Can 35SiMn QT-SPRING be welded?
Not readily — weldability is rated poor (30/100). Poor weldability (CE ≈ 0.8–0.9): preheat 250–350 °C, use low-hydrogen consumables, keep interpass temperature and temper immediately after welding to avoid cold cracking.
What surface finishes work on 35SiMn QT-SPRING?
No corrosion resistance: protect with phosphate + oil, black oxide, zinc or Dacromet coating; hard chrome or induction hardening plus grinding for wear surfaces (bake after plating to avoid hydrogen embrittlement).
Can 35SiMn QT-SPRING be formed, bent or molded?
Hot forge/roll 1150 → 850 °C with slow cooling or immediate annealing; cold bending only in the annealed state with generous radii — Q&T material cracks.
What is the maximum service temperature of 35SiMn QT-SPRING?
35SiMn QT-SPRING is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 35SiMn-QT and 35SiMn-A?
QT is the default condition — use the standard quenched (900 °C, water) and 570 °C tempered condition for shafts, gears, rods and fasteners; it delivers the 780 MPa yield and 950 MPa tensile values quoted in GB/T 3077. A: softest supply condition (≤229 HBW per GB/T 3077) for deep machining, cold shearing or straightening before final Q&T. Yield strength is 780 MPa in QT versus 370 MPa in A.
Sources
- GB/T 699 / GB/T 702 bar dimensional and delivery requirements — SAC (2015)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 4 — Heat Treating — ASM International (1991)
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.