Steel 50#
GB 50#
50# is a Chinese GB/T 699 medium-carbon quality structural steel (~0.50 % C) supplied mostly as hot-rolled or normalized bar, plate and forging stock.
Values for the HR condition
50# tempers and conditions
50# is supplied in 8 conditions, soft to hard. HR 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 | Softest condition, used before heavy machining or cold forming of 50# stock. | 365 | 640 | 24 | 190 HB | — |
HRDefault Hot rolled | Default stock condition for 50# round bar and plate; machined then heat treated by the user. | 400 | 700 | 16 | 210 HB | — |
Normalized | Standard GB/T 699 reference condition — uniform fine pearlite, better strength and consistency than as-rolled. | 430 | 750 | 18 | 217 HB | — |
Cold drawn | Choose for straight, close-tolerance bright bar with raised yield strength; low ductility and residual stress. | 600 | 720 | 10 | 210 HB | — |
Quenched and tempered | General-purpose toughened condition for shafts, gear blanks and rolls needing strength with usable ductility. | 620 | 850 | 16 | 25 HRC | — |
Induction hardened | Pick for gear teeth, spline and journal surfaces needing 50–58 HRC wear resistance with a tough tempered core. | 620 | 850 | 14 | 55 HRC | 8.5 % IACS |
Quenched and tempered ~480–520 °C | Specify when a defined medium hardness is required for wear-loaded shafts and gears that still need machining. | 780 | 980 | 13 | 30 HRC | — |
Quenched and tempered ~380–420 °C | High-strength condition for spring washers, wear plates and highly loaded pins; toughness and machinability drop sharply. | 1,080 | 1,280 | 10 | 40 HRC | — |
What is 50#?
50# is a Chinese GB/T 699 medium-carbon quality structural steel (~0.50 % C) supplied mostly as hot-rolled or normalized bar, plate and forging stock. It is chosen when 45# does not give enough strength or wear resistance: after quench-and-temper or induction hardening it reaches 750–1300 MPa with good surface hardness, making it standard for gears, crankshafts, rolls, shafts, springs-washers and machine parts. Limits are poor weldability (preheat/post-weld temper needed above ~0.45 % C), low hardenability in thick sections (water/oil quench, ≤ ~30 mm effective depth), notch sensitivity at low temperature and essentially no corrosion resistance. 50# 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). 50# has a yield strength of 400 MPa (58 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 60% of steel grades. Elongation at break is 16% and the elastic modulus is 207 GPa (30 Msi).
What is 50# used for?
- Shafts
- Cold work blanks
- Springs
Advantages
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
50# properties
Typical room-temperature values for 50#-HR; bars are the position among steel grades.
Physical3
50# 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).
Mechanical15
50# has a yield strength of 400 MPa (58 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 60% of steel grades. Elongation at break is 16% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
50# is rated for continuous service to 400°C (752 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
50# conducts electricity at 9.5 % IACS, better than 75% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 50# takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
50#'s machinability is fair (50/100, worse than 53% of steel grades); weldability fair (35/100); formability fair (35/100).
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. 50# is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 50#
Is 50# easy to machine?
Machine in annealed/normalized state at ~50 % of 1212 speeds; carbide tooling, positive rake, generous coolant — above 30 HRC use CBN/coated carbide and lower feeds.
Can 50# be welded?
Poor weldability at 0.50 % C: use low-hydrogen electrodes, 150–260 °C preheat, controlled interpass and 600 °C stress relief to avoid martensitic cracking in the HAZ.
Can 50# be formed, bent or molded?
Hot forge/roll at 1150–850 °C then normalize; cold bending only in annealed condition with generous radii (≥3 t).
Manufacturability
The process limits FabDigit applies to 50#. Every 50# part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better50 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better35 / 100 |
|---|---|
| Weldability | Better35 / 100 |
50# 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 | 0.47 – 0.55 | 0.5 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Crresidual max | ≤ 0.25 | |
| Niresidual max | ≤ 0.3 | |
| Curesidual max | ≤ 0.25 | |
| Fe | balance |
What surface finishes work on 50#?
No anodizing — protect with phosphating + oil, blackening, zinc/chrome plating or paint; hardened surfaces grind and polish well but rust quickly unprotected.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
How much does 50# cost?
50# 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.
50# — frequently asked
What is 50# used for?
50# is typically used for shafts, cold work blanks and springs. In short: medium-carbon plate stock.
What is the yield strength of 50#?
50# has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 50# easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in annealed/normalized state at ~50 % of 1212 speeds; carbide tooling, positive rake, generous coolant — above 30 HRC use CBN/coated carbide and lower feeds.
Can 50# be welded?
With care — weldability is rated fair (35/100). Poor weldability at 0.50 % C: use low-hydrogen electrodes, 150–260 °C preheat, controlled interpass and 600 °C stress relief to avoid martensitic cracking in the HAZ.
What surface finishes work on 50#?
No anodizing — protect with phosphating + oil, blackening, zinc/chrome plating or paint; hardened surfaces grind and polish well but rust quickly unprotected.
Can 50# be formed, bent or molded?
Hot forge/roll at 1150–850 °C then normalize; cold bending only in annealed condition with generous radii (≥3 t).
What is the maximum service temperature of 50#?
50# 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.
What is the difference between 50#-HR and 50#-QT?
HR is the default condition — default stock condition for 50# round bar and plate; machined then heat treated by the user. QT: general-purpose toughened condition for shafts, gear blanks and rolls needing strength with usable ductility. Yield strength is 400 MPa in HR versus 620 MPa in QT.
How much does 50# cost?
50# 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.
Can FabDigit make parts in 50#?
Yes — 50# 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 Quality carbon structural steels (grade 50) — SAC (2015)
- GB/T 702 Hot-rolled steel bars — dimensions and tolerances — SAC (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels (SAE 1050 data) — 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.