Steel 5150 · heat-treated state
Steel 5150 Q&T 650C
Properties of the Q&T 650C condition, compared with the other 5150 tempers.
Tough, lower-strength condition for shafts and fasteners needing impact resistance and easier machining.
What is 5150 Q&T 650C?
5150 Q&T 650C is 5150 heat treated to Q&T 650C — tough, lower-strength condition for shafts and fasteners needing impact resistance and easier machining. 5150 Q&T 650C has a yield strength of 800 MPa (116 ksi) and a tensile strength of 870 MPa (126 ksi) — stronger than 86% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi). 5150 Q&T 650C 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; Q&T 650C is available on request or by drawing note.
Advantages
- High strength — 800 MPa (116 ksi), better than 86% of steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 77% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
5150 Q&T 650C properties
Typical room-temperature values for 5150 Q&T 650C — 9 properties are specific to this condition; the rest are grade-level values shared by every 5150 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
5150 Q&T 650C 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
5150 Q&T 650C has a yield strength of 800 MPa (116 ksi) and a tensile strength of 870 MPa (126 ksi) — stronger than 86% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
5150 Q&T 650C is rated for continuous service to 300°C (572 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.4 µm/m·K (6.89 µin/in·°F).
Electrical3
5150 Q&T 650C conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 5150 Q&T 650C takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
5150 Q&T 650C's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (25/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 5150 tempers and conditions
5150 is also supplied in 10 other conditions. The full side-by-side table is on the 5150 overview.
- HRDefaultAs-rolled bar/plate stock for parts that will be machined and then heat treated.460 MPa yield · 229 HB
- Q&T 205CMaximum-hardness condition for wear surfaces and small springs; very low ductility and notch sensitivity.1,730 MPa yield · 52 HRC
- Q&T 315CHigh-hardness spring condition; avoid this range if impact toughness matters (tempered-martensite embrittlement).1,570 MPa yield · 49 HRC
- Q&T 425CBalanced high-strength spring/gear condition, typical for leaf and coil springs.1,360 MPa yield · 44 HRC
- Q&TGeneric oil-quenched and tempered condition (~540 °C temper) — the usual structural condition for shafts, gears and heavy springs.1,080 MPa yield · 37 HRC
- Q&T 540CGeneral-purpose machine-part condition with good strength/toughness balance.1,080 MPa yield · 36 HRC
- Q&T 650CTough, lower-strength condition for shafts and fasteners needing impact resistance and easier machining.800 MPa yield · 27 HRC
- NormalizedAir cooled from ~870 °C for uniform fine grain and improved machined-part consistency before final hardening.530 MPa yield · 25 HRC
- AnnealedSoftest condition (spheroidize/full anneal) for heavy machining or cold forming before hardening.360 MPa yield · 197 HB
Working with 5150 Q&T 650C
Is 5150 easy to machine?
Machine in the annealed or ≤32 HRC condition with carbide tooling and rigid setups; above 40 HRC use CBN/ceramic or grinding.
Can 5150 be welded?
Poor weldability (CE ≈ 0.75) — preheat 250–350 °C, low-hydrogen consumables and immediate post-weld temper are mandatory.
Can 5150 be formed, bent or molded?
Hot forge 1150–1200 °C, finish above 900 °C, then anneal or normalize; cold forming only for light bends in annealed strip.
What surface finishes work on 5150?
No natural corrosion resistance — phosphate + oil, black oxide, zinc plating, paint or hard chrome; shot peen springs to boost fatigue life.
5150 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 | 0.48 – 0.53 | 0.5 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.7 – 0.9 | 0.8 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
5150 Q&T 650C — frequently asked
What is 5150 Q&T 650C used for?
5150 Q&T 650C is typically used for coil springs, leaf springs, axle and drive shafts, gears and gear blanks, structural forgings and torsion bars. In short: workhorse chrome spring bar.
What is the yield strength of 5150 Q&T 650C?
5150 Q&T 650C has a typical yield strength of 800 MPa (116 ksi) and a tensile strength of 870 MPa (126 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 5150 Q&T 650C easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed or ≤32 HRC condition with carbide tooling and rigid setups; above 40 HRC use CBN/ceramic or grinding.
Can 5150 Q&T 650C be welded?
Not readily — weldability is rated poor (25/100). Poor weldability (CE ≈ 0.75) — preheat 250–350 °C, low-hydrogen consumables and immediate post-weld temper are mandatory.
What surface finishes work on 5150 Q&T 650C?
No natural corrosion resistance — phosphate + oil, black oxide, zinc plating, paint or hard chrome; shot peen springs to boost fatigue life.
Can 5150 Q&T 650C be formed, bent or molded?
Hot forge 1150–1200 °C, finish above 900 °C, then anneal or normalize; cold forming only for light bends in annealed strip.
What is the maximum service temperature of 5150 Q&T 650C?
5150 Q&T 650C is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 5150-HR and 5150-CD?
HR is the default condition — as-rolled bar/plate stock for parts that will be machined and then heat treated. CD: cold-drawn bar giving tight size tolerance, better surface finish and higher as-supplied strength than hot rolled. Yield strength is 460 MPa in HR versus 760 MPa in CD.
Can FabDigit make parts in 5150 Q&T 650C?
Yes — 5150 Q&T 650C is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- GB/T 3077 (50Cr) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
- Mysteel / SMM (2025)
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.