Steel C30-QT315
Heat-treated state
EN C30 · AISI/SAE 1030 · JIS S30C · GB 30
QT315 = q&T 315 °C
High strength with modest ductility for small hardened pins and levers.
Values for the QT315 condition
Other C30 tempers and conditions
C30 is listed in 11 conditions; see the grade overview at C30.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot rolled | Cheapest stock condition for weldments, brackets and parts to be machined and later heat treated. | 260 | 470 | 20 | 137 HB | — |
Spheroidize annealed | Choose for cold heading, thread rolling or severe cold forming of fasteners and forged blanks. | 290 | 440 | 35 | 120 HB | 10.5 % IACS |
Solution annealed | Softest, most stable condition for deep machining, cold bending or stress-free blanks before hardening. | 340 | 465 | 31 | 126 HB | — |
NDefault Normalized | Pick the normalized 870–900 °C air-cooled delivery and test condition for uniform fine pearlite balancing 345 MPa yield, 30% elongation and machinability before any further hardening. | 345 | 520 | 30 | 149 HB | — |
Induction hardened | Pick when journals or teeth need a hard wear surface (≈50 HRC) on a tough, ductile core. | 360 | 560 | 22 | 52 HRC | 10 % IACS |
Cold drawn | Bright, close-tolerance bar with higher yield and better surface finish; use where no further heat treatment is planned. | 440 | 525 | 12 | 149 HB | — |
Q&T 650 °C | High-temper condition when maximum toughness and machinability are wanted after hardening. | 441 | 586 | 32 | 17 HRC | — |
Q&T 540 °C | Most common quenched-and-tempered condition for general machine shafts and forgings. | 517 | 669 | 28 | 25 HRC | — |
Q&T 425 °C | Use quenching with 425 °C tempering (≈32 HRC) for loaded shafts requiring about 731 MPa tensile; hardness rises to 302 HB while elongation falls to 23%. | 579 | 731 | 23 | 32 HRC | — |
QT315This page Q&T 315 °C | High strength with modest ductility for small hardened pins and levers. | 621 | 800 | 19 | 42 HRC | — |
Q&T 205 °C | Maximum hardness/wear on thin sections; low toughness, use only for small wear parts. | 648 | 848 | 17 | 50 HRC | — |
What is C30-QT315?
C30-QT315 is C30 heat treated to QT315 — high strength with modest ductility for small hardened pins and levers. C30-QT315 has a yield strength of 621 MPa (90.1 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 79% of steel grades. Elongation at break is 19% and the elastic modulus is 205 GPa (29.7 Msi). C30-QT315 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). N is the default condition FabDigit quotes; QT315 is available on request or by drawing note.
Advantages
- Conducts heat well — 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
- High strength — 621 MPa (90.1 ksi), better than 79% of steel grades
Limitations
- Limited service temperature — 280°C (536 °F), worse than 82% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
C30-QT315 properties
Typical room-temperature values for C30-QT315; 10 are specific to this condition. Other listed values are C30 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
C30-QT315 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).
Mechanical16
C30-QT315 has a yield strength of 621 MPa (90.1 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 79% of steel grades. Elongation at break is 19% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
C30-QT315 is rated for continuous service to 280°C (536 °F). It conducts heat at 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
C30-QT315 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 C30-QT315 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
C30-QT315's machinability is good (60/100, better than 83% of steel grades); weldability good (65/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C30-QT315
Is C30 easy to machine?
Machines readily at ~70 % of 1212 in the normalized or cold-drawn state; annealed material can smear, so use sharp carbide, 120–200 m/min and good coolant.
Can C30 be welded?
Weldable by SMAW/GMAW with low-hydrogen consumables; at 0.30 % C preheat 100–150 °C and post-weld stress relief on thick or restrained joints to avoid HAZ cracking.
Can C30 be formed, bent or molded?
Good hot forgeability at 1100–1200 °C; cold bending needs generous radii (≥2t) and is best done annealed or spheroidized.
What surface finishes work on C30?
No anodizing — protect with zinc/nickel plating, phosphate + oil, black oxide or paint; takes a fine polish but will flash-rust unless coated.
C30 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 699 steel 30; AISI 1030 = 0.28-0.34 | 0.27 – 0.34 | 0.3 |
| Si | 0.17 – 0.37 | 0.25 |
| MnAISI 1030 = 0.60–0.90 | 0.5 – 0.8 | 0.65 |
| PC30E/1.1178 ≤0.025 | ≤ 0.04 | 0.02 |
| SC30E ≤0.035, C30R sulfur-treated | ≤ 0.04 | 0.02 |
| Crresidual | ≤ 0.25 | 0.05 |
| Niresidual | ≤ 0.3 | 0.05 |
| Curesidual | ≤ 0.25 | 0.05 |
| Fe | balance | — |
C30-QT315 — frequently asked
What is C30-QT315 used for?
C30-QT315 is typically used for shafts, bolts, small forgings, machine parts and gears (light duty). In short: most weldable medium carbon; good machinability and formability; lower-strength C35 alternative.
What is the yield strength of C30-QT315?
C30-QT315 has a typical yield strength of 621 MPa (90.1 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 79% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is C30-QT315 easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machines readily at ~70 % of 1212 in the normalized or cold-drawn state; annealed material can smear, so use sharp carbide, 120–200 m/min and good coolant.
Can C30-QT315 be welded?
Yes — weldability is rated good (65/100). Weldable by SMAW/GMAW with low-hydrogen consumables; at 0.30 % C preheat 100–150 °C and post-weld stress relief on thick or restrained joints to avoid HAZ cracking.
What surface finishes work on C30-QT315?
No anodizing — protect with zinc/nickel plating, phosphate + oil, black oxide or paint; takes a fine polish but will flash-rust unless coated.
Can C30-QT315 be formed, bent or molded?
Good hot forgeability at 1100–1200 °C; cold bending needs generous radii (≥2t) and is best done annealed or spheroidized.
What is the maximum service temperature of C30-QT315?
C30-QT315 is rated for continuous use to about 280°C (536 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C30-N and C30-QT205?
N is the default condition — pick the normalized 870–900 °C air-cooled delivery and test condition for uniform fine pearlite balancing 345 MPa yield, 30% elongation and machinability before any further hardening. QT205: maximum hardness/wear on thin sections; low toughness, use only for small wear parts. Yield strength is 345 MPa in N versus 648 MPa in QT205.
Sources
- EN 10083-2 / EN 10277 (C30, C30E, 1.0528/1.1178) — CEN (2006)
- ASTM A29/A29M and SAE J403 (1030) — ASTM / SAE (2020)
- JIS G 4051 (S30C) — JSA (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating; Vol.16 — Machining — 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.