Steel 35CrMo-SA (Spheroidize annealed)
Heat-treated state
GB 35CrMo · AISI/SAE 4137
Choose for cold heading/upsetting of high-strength bolts and for deep boring where the softest possible structure is wanted.
Values for the SA condition
Other 35CrMo tempers and conditions
35CrMo is listed in 11 conditions; see the grade overview at 35CrMo.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SAThis page Spheroidize annealed | Choose for cold heading/upsetting of high-strength bolts and for deep boring where the softest possible structure is wanted. | 380 | 620 | 27 | 170 HB | 8.1 % IACS |
full anneal (~840–860 °C, slow cool) | Pick for maximum machinability and dimensional stability before final heat treatment or for cold forming of blanks. | 420 | 680 | 24 | 197 HB | — |
HRDefault Hot rolled | Most stocked form: as-rolled round bar or plate destined for machining and subsequent quench-and-temper by the part maker. | 490 | 800 | 17 | 200 HB | — |
Normalized and tempered | Compromise condition for large forgings and pressure parts where oil quenching is impractical. | 600 | 850 | 19 | 24 HRC | 7.8 % IACS |
~870 °C, air cooled | Use for uniform fine-grain structure and moderate strength in large sections that will not be quenched. | 650 | 1,000 | 18 | 30 HRC | — |
Cold rolled | Thin strip/sheet condition for stamped and formed parts that will be hardened after blanking. | 660 | 830 | 11 | 23 HRC | 7.8 % IACS |
Cold drawn | Choose for close-tolerance, bright-surface bar used as-supplied in shafting and studs without further heat treatment. | 680 | 850 | 12 | 250 HB | — |
Tempered to ~950–1050 MPa | Tough general-purpose hardness band for machined shafts and NACE MR0175-conscious sour-service parts (≤22 HRC bands aside). | 860 | 1,000 | 16 | 30 HRC | — |
Quenched and tempered | Standard delivered/certified strength condition for shafts, connecting rods and grade 10.9/12.9 fasteners. | 880 | 1,030 | 14 | 33 HRC | — |
Tempered to ~1100–1250 MPa | Higher-strength band for gears, high-strength bolting and drill-string components where wear matters more than toughness. | 1,050 | 1,170 | 13 | 36 HRC | — |
Low-temperature temper, ~1300–1450 MPa | Maximum practical strength band for 35CrMo; use only where impact loading and hydrogen exposure are low. | 1,230 | 1,370 | 11 | 42 HRC | — |
What is 35CrMo-SA?
35CrMo-SA is 35CrMo heat treated to SA — choose for cold heading/upsetting of high-strength bolts and for deep boring where the softest possible structure is wanted. 35CrMo-SA has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi). 35CrMo-SA 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). HR is the default condition FabDigit quotes; SA is available on request or by drawing note.
Advantages
- Easy to machine — 65/100, better than 93% of steel grades
- Ductile — tolerates forming and impact — 27%, better than 86% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- Forms and bends easily — 65/100, better than 81% of steel grades
35CrMo-SA properties
Typical room-temperature values for 35CrMo-SA; 22 are specific to this condition. Other listed values are 35CrMo reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
35CrMo-SA 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).
Mechanical14
35CrMo-SA has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
35CrMo-SA is rated for continuous service to 450°C (842 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
35CrMo-SA conducts electricity at 8.1 % IACS, better than 61% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 35CrMo-SA takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
35CrMo-SA's machinability is good (65/100, better than 93% of steel grades); weldability fair (45/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 35CrMo-SA
Is 35CrMo easy to machine?
Machine in the annealed or ≤32 HRC condition with coated carbide, rigid setups and generous coolant; above 38 HRC expect ceramic/CBN finishing or grinding.
Can 35CrMo be welded?
Weldable with low-hydrogen electrodes but requires 200–300 °C preheat, matching Cr-Mo filler and 600–680 °C PWHT to avoid HAZ cold cracking.
Can 35CrMo be formed, bent or molded?
Hot forge at 1150–850 °C then normalize; cold forming only from spheroidize-annealed stock, with generous bend radii.
What surface finishes work on 35CrMo?
No natural corrosion protection — specify oiling, phosphate, zinc or Zn-Ni plating (bake to relieve hydrogen), QPQ/nitriding for wear, or paint.
35CrMo 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 | 0.35 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.4 – 0.7 | 0.55 |
| Cr | 0.8 – 1.1 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| P≤ 0.025 for high-grade quality | ≤ 0.03 | 0.02 |
| S≤0.025 for high-grade quality | ≤ 0.03 | 0.02 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.2 | — |
| Fe | balance | — |
35CrMo-SA — frequently asked
What is 35CrMo-SA used for?
35CrMo-SA is typically used for bolts, industrial drive shafts and crankshafts. In short: premium Cr-Mo bar.
What is the yield strength of 35CrMo-SA?
35CrMo-SA has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 35CrMo-SA easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Machine in the annealed or ≤32 HRC condition with coated carbide, rigid setups and generous coolant; above 38 HRC expect ceramic/CBN finishing or grinding.
Can 35CrMo-SA be welded?
With care — weldability is rated fair (45/100). Weldable with low-hydrogen electrodes but requires 200–300 °C preheat, matching Cr-Mo filler and 600–680 °C PWHT to avoid HAZ cold cracking.
What surface finishes work on 35CrMo-SA?
No natural corrosion protection — specify oiling, phosphate, zinc or Zn-Ni plating (bake to relieve hydrogen), QPQ/nitriding for wear, or paint.
Can 35CrMo-SA be formed, bent or molded?
Hot forge at 1150–850 °C then normalize; cold forming only from spheroidize-annealed stock, with generous bend radii.
What is the maximum service temperature of 35CrMo-SA?
35CrMo-SA is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 35CrMo-HR and 35CrMo-CD?
HR is the default condition — most stocked form: as-rolled round bar or plate destined for machining and subsequent quench-and-temper by the part maker. CD: choose for close-tolerance, bright-surface bar used as-supplied in shafting and studs without further heat treatment. Yield strength is 490 MPa in HR versus 680 MPa in CD.
Can FabDigit make parts in 35CrMo-SA?
Yes — 35CrMo-SA is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 699 / GB/T 702 (bar dimensions & delivery condition) — SAC (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (4130/4135/4140 data) — ASM International (1990)
- ASM Handbook Vol.16 — Machining (machinability ratings) — ASM International (1989)
- Cr-Mo structural steel 1.7220 / 34CrMo4 datasheet — Böhler / Deutsche Edelstahlwerke (2021)
- MMPDS-Handbook typical values for 4130/4140 low-alloy steel — Battelle / FAA (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.