Steel 35CrMnSiA
GB 35CrMnSiA
35CrMnSiA (cross-referenced to AISI 4140) is a chromium-manganese-silicon quenched-and-tempered structural steel, a higher-carbon relative of 30CrMnSiA that reaches very high strength after quenching and low-temperature tempering.
Reference datasheet — 35CrMnSiA 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 QT230 condition
35CrMnSiA tempers and conditions
35CrMnSiA is supplied in 8 conditions, soft to hard. QT230 is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for machining, cold sawing and blank preparation before final quench-and-temper. | 450 | 720 | 18 | 215 HB | — |
Hot rolled | Mill supply condition for bar and billet to be re-heat-treated by the user; hard and stringy, not a service condition. | 620 | 900 | 13 | 30 HRC | 7.5 % IACS |
Normalized | Grain refinement and structure homogenisation of forgings before final hardening; also used for moderately loaded parts. | 700 | 950 | 14 | 31 HRC | 7.5 % IACS |
Cold drawn | Small-diameter bright bar for parts machined to size before hardening; tighter tolerance, higher as-supplied strength. | 720 | 880 | 9 | 27 HRC | 7.5 % IACS |
Q&T | Toughest quench-and-temper level, for parts that must be machined after heat treatment or see impact loading. | 950 | 1,100 | 15 | 34 HRC | — |
Q&T | Balanced condition around 40 HRC for heavily loaded shafts and connecting rods needing more toughness than the 230 °C temper. | 1,150 | 1,300 | 13 | 40 HRC | — |
Q&T | Slight strength trade for better ductility; avoid dwelling at 300–400 °C where temper embrittlement is worst. | 1,330 | 1,550 | 11 | 45 HRC | 6.5 % IACS |
QT230Default Q&T | The GB/T 3077 specification condition — maximum strength (≥1620 MPa) for landing-gear fittings, high-strength bolts and rocket structures. | 1,400 | 1,700 | 10 | 48 HRC | — |
Supply forms, finishes and certifications
Ways 35CrMnSiA is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
WIRE-HD | Patented / heat-treated wire and strip | Supply form |
ISO-Q | Isothermal (bainitic) quench | Certification |
What is 35CrMnSiA?
35CrMnSiA (cross-referenced to AISI 4140) is a chromium-manganese-silicon quenched-and-tempered structural steel, a higher-carbon relative of 30CrMnSiA that reaches very high strength after quenching and low-temperature tempering. It is specified for aircraft structural parts, high-strength fasteners and shafts, and is supplied hot-rolled, annealed, normalized and cold-drawn, plus isothermally quenched and hard-drawn wire conditions. In the default temper it gives 1400 MPa yield, 1700 MPa tensile, 10 % elongation and 460 HB (48 HRC), with service to 200 °C. Weldability (25) and formability (10) are poor; 40CrMnMo is easier to weld and machine at lower strength. 35CrMnSiA has a density of 7.82 g/cm³ (0.283 lb/in³), lighter than 82% of steel grades. It melts at 1,420°C (2,588 °F). 35CrMnSiA has a yield strength of 1,400 MPa (203 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 96% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi).
What is 35CrMnSiA used for?
- aircraft structural parts
- high-strength fasteners
- shafts
Advantages
- High strength — 1,400 MPa (203 ksi), better than 96% of steel grades
- Polishes to a fine finish — 75/100, better than 94% of steel grades
Limitations
- Limited formability — 10/100, worse than 95% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Limited ductility — 10%, worse than 91% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
- Difficult to machine — 30/100, worse than 89% of steel grades
35CrMnSiA properties
Typical room-temperature values for 35CrMnSiA-QT230; bars are the position among steel grades.
Physical3
35CrMnSiA has a density of 7.82 g/cm³ (0.283 lb/in³), lighter than 82% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
35CrMnSiA has a yield strength of 1,400 MPa (203 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 96% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
35CrMnSiA is rated for continuous service to 200°C (392 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical2
35CrMnSiA has an electrical resistivity of 2.7×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 35CrMnSiA takes about 29 MJ of energy and emits 2.3 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 25%.
Manufacturability7
35CrMnSiA's machinability is poor (30/100, worse than 89% of steel grades); weldability poor (25/100); formability not recommended (10/100).
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. 35CrMnSiA is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 35CrMnSiA
Is 35CrMnSiA easy to machine?
Machine in the annealed (≤229 HB) state with carbide tools; at 45–50 HRC only finish grinding, hard turning with CBN or EDM is practical.
Can 35CrMnSiA be welded?
Poor weldability — high carbon plus 1.2 % Si gives crack-prone HAZ; if unavoidable use 200–350 °C preheat, low-hydrogen filler, and immediate post-weld temper at the part's temper temperature.
Can 35CrMnSiA be formed, bent or molded?
Hot forge 1150–850 °C with slow cooling or immediate anneal; cold forming only in the annealed condition and with generous bend radii.
35CrMnSiA 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 |
|---|---|---|
| CGB/T 3077 | 0.32 – 0.39 | 0.35 |
| Siraises temper resistance and hardenability | 1.1 – 1.4 | 1.25 |
| Mn | 0.8 – 1.1 | 0.95 |
| Cr | 1.1 – 1.4 | 1.25 |
| PA = high-grade quality steel, low P/S | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Niresidual | ≤ 0.3 | |
| Curesidual | ≤ 0.25 | |
| Fe | balance |
What surface finishes work on 35CrMnSiA?
Grind then zinc, cadmium or Zn-Ni plate, phosphate or prime-and-paint; bake at 190–200 °C for ≥4 h after plating/pickling to relieve hydrogen embrittlement, and shot-peen fillets to restore fatigue life.
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 35CrMnSiA in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 4140
How much does 35CrMnSiA cost?
35CrMnSiA 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.
35CrMnSiA — frequently asked
What is 35CrMnSiA used for?
35CrMnSiA is typically used for aircraft structural parts, high-strength fasteners and shafts. In short: very high strength after Q&T; crack-prone HAZ; aircraft structural grade.
What is the yield strength of 35CrMnSiA?
35CrMnSiA has a typical yield strength of 1,400 MPa (203 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 96% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 35CrMnSiA easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% of steel grades). Machine in the annealed (≤229 HB) state with carbide tools; at 45–50 HRC only finish grinding, hard turning with CBN or EDM is practical.
Can 35CrMnSiA be welded?
Not readily — weldability is rated poor (25/100). Poor weldability — high carbon plus 1.2 % Si gives crack-prone HAZ; if unavoidable use 200–350 °C preheat, low-hydrogen filler, and immediate post-weld temper at the part's temper temperature.
What surface finishes work on 35CrMnSiA?
Grind then zinc, cadmium or Zn-Ni plate, phosphate or prime-and-paint; bake at 190–200 °C for ≥4 h after plating/pickling to relieve hydrogen embrittlement, and shot-peen fillets to restore fatigue life.
Can 35CrMnSiA be formed, bent or molded?
Hot forge 1150–850 °C with slow cooling or immediate anneal; cold forming only in the annealed condition and with generous bend radii.
What is the maximum service temperature of 35CrMnSiA?
35CrMnSiA is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 35CrMnSiA-QT230 and 35CrMnSiA-A?
QT230 is the default condition — the GB/T 3077 specification condition — maximum strength (≥1620 MPa) for landing-gear fittings, high-strength bolts and rocket structures. A: choose for machining, cold sawing and blank preparation before final quench-and-temper. Yield strength is 1,400 MPa in QT230 versus 450 MPa in A.
How much does 35CrMnSiA cost?
35CrMnSiA 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
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
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.