Steel C35E +QT (Quenched and tempered)
Heat-treated state · default condition
EN C35E
Default condition for loaded shafts, bolts and machine parts needing the best strength/toughness balance in sections up to ~40 mm.
Values for the +QT condition
Other C35E tempers and conditions
C35E is listed in 7 conditions; see the grade overview at C35E.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for maximum cold formability and easiest machining before final heat treatment. | 300 | 540 | 24 | 160 HB | — |
Hot rolled | Cheapest supply condition for parts that will be heat treated by the customer or for lightly loaded structural use. | 310 | 550 | 20 | 160 HB | — |
Normalized | Standard low-cost condition for uniform fine-grained bar and forgings of moderate strength. | 330 | 570 | 21 | 170 HB | — |
Normalized and tempered | Choose when normalizing stresses must be relieved and slightly higher toughness/dimensional stability is needed at near-normalized strength. | 340 | 580 | 22 | 172 HB | — |
+QTDefaultThis page Quenched and tempered | Default condition for loaded shafts, bolts and machine parts needing the best strength/toughness balance in sections up to ~40 mm. | 430 | 660 | 20 | 15 HRC | — |
+QT then induction surface hardened | Use where a tough Q&T core must carry load while journals, cams or gear teeth need a hard, wear- and fatigue-resistant surface. | 430 | 660 | 16 | 54 HRC | — |
Cold drawn | Pick for close-tolerance bright bar with higher yield strength when parts are made mostly by turning without further heat treatment. | 500 | 640 | 11 | 195 HB | — |
What is C35E +QT?
C35E +QT is C35E heat treated to +QT — default condition for loaded shafts, bolts and machine parts needing the best strength/toughness balance in sections up to ~40 mm. C35E +QT has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 51% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi). C35E +QT 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).
Advantages
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
Limitations
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
C35E +QT properties
Typical room-temperature values for C35E +QT; 17 are specific to this condition. Other listed values are C35E reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
C35E +QT 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).
Mechanical17
C35E +QT has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 51% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
C35E +QT is rated for continuous service to 400°C (752 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
C35E +QT 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 C35E +QT takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
C35E +QT's machinability is good (55/100, better than 62% of steel grades); weldability fair (50/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C35E +QT
Is C35E easy to machine?
Machines well at ~180–220 HB with carbide at 150–250 m/min; annealed material can smear, so prefer +N or +QT for good chip control and surface finish.
Can C35E be welded?
Weldable with low-hydrogen SMAW/GMAW but CE≈0.45 means preheat 150–250 °C, control interpass, and PWHT or re-temper at 550–650 °C to avoid hard HAZ cracking.
Can C35E be formed, bent or molded?
Hot forge 850–1150 °C then normalize; cold bending/heading only in +A or +N condition with generous radii — cold formability is limited by the 0.35 % C level.
What surface finishes work on C35E?
No corrosion resistance of its own: use phosphate + oil, black oxide, zinc or hard-chrome plating, or paint; polishes well after Q&T but will rust unless protected.
C35E 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 |
|---|---|---|
| CEN 10083-2 heat analysis | 0.32 – 0.39 | 0.35 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.5 – 0.8 | 0.65 |
| P | ≤ 0.03 | 0.02 |
| S'E' quality = controlled low sulfur; C35R has 0.020–0.040 S | ≤ 0.04 | 0.02 |
| Crresidual | ≤ 0.4 | 0.1 |
| Moresidual | ≤ 0.1 | 0.02 |
| Niresidual; Cr+Mo+Ni ≤ 0.63 | ≤ 0.4 | 0.1 |
| Fe | balance | — |
C35E +QT — frequently asked
What is C35E +QT used for?
C35E +QT is typically used for shafts, bolts, connecting rods and machine parts. In short: workhorse Q&T shaft steel; cheaper than 42CrMo4; mid-range carbon strength.
What is the yield strength of C35E +QT?
C35E +QT has a typical yield strength of 430 MPa (62.4 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 51% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is C35E +QT easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines well at ~180–220 HB with carbide at 150–250 m/min; annealed material can smear, so prefer +N or +QT for good chip control and surface finish.
Can C35E +QT be welded?
With care — weldability is rated fair (50/100). Weldable with low-hydrogen SMAW/GMAW but CE≈0.45 means preheat 150–250 °C, control interpass, and PWHT or re-temper at 550–650 °C to avoid hard HAZ cracking.
What surface finishes work on C35E +QT?
No corrosion resistance of its own: use phosphate + oil, black oxide, zinc or hard-chrome plating, or paint; polishes well after Q&T but will rust unless protected.
Can C35E +QT be formed, bent or molded?
Hot forge 850–1150 °C then normalize; cold bending/heading only in +A or +N condition with generous radii — cold formability is limited by the 0.35 % C level.
What is the maximum service temperature of C35E +QT?
C35E +QT 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.
Sources
- EN 10083-2 Steels for quenching and tempering — Non-alloy steels — CEN (2006)
- EN 10277 Bright steel products — technical delivery conditions — CEN (2018)
- 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)
- Stahlschlüssel / Key to Steel — 1.1181 (Ck35) — Verlag Stahlschlüssel Wegst (2023)
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.