Steel 20#
GB 20#
20# is a low-carbon quality carbon structural steel to GB/T 699 with 0.17–0.23 % C, comparable to AISI 1020 and DIN C22.
Values for the CD condition
20# tempers and conditions
20# is supplied in 6 conditions, soft to hard. CD is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — pick for deep drawing, severe cold forming or stress relief before carburizing. | 250 | 400 | 33 | 121 HB | — |
Hot rolled | Cheapest form for welded structures, flanges and machined parts where scale and looser tolerance are acceptable. | 265 | 440 | 28 | 145 HB | — |
Normalized | Standard reference condition of GB/T 699 test bars; uniform fine grain, best toughness/strength balance for pressure parts. | 275 | 450 | 29 | 140 HB | — |
CDDefault Cold drawn | Default stock condition for small round bar, shafting and precision tube; best dimensional accuracy, surface finish and machinability. | 395 | 510 | 13 | 160 HB | — |
Quenched and tempered | Used on small pins and fasteners where a modest strength lift is wanted; hardenability is poor, so section size must stay under ~15 mm. | 430 | 600 | 20 | 14 HRC | 10.5 % IACS |
Carburized, quenched and low-temperature tempered | Choose for small gears, cams, bushings and wear pins needing a 0.3–1.2 mm hard case over a tough low-carbon core. | 450 | 640 | 12 | 59 HRC | — |
What is 20#?
20# is a low-carbon quality carbon structural steel to GB/T 699 with 0.17–0.23 % C, comparable to AISI 1020 and DIN C22. Its ductility, toughness and weldability (score 92) are excellent, it cold bends and stamps readily, and carburizing produces a hard wear-resistant surface over a tough core; typical values are 395 MPa yield, 510 MPa tensile, 13 % elongation and 160 HB (83 HRB) in hot rolled, cold drawn, normalized, annealed, Q&T and carburized conditions. Limits are low strength, poor hardenability with a shallow water-quench hardened layer, and poor corrosion resistance requiring paint or plating; it is not suited to high-stress or sustained high-temperature service. Use 45# where more strength is needed. 20# has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F). 20# has a yield strength of 395 MPa (57.3 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 63% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
What is 20# used for?
- General fabrication
- Brackets
- Welded plate
Advantages
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Easy to machine — 65/100, better than 93% of steel grades
- Readily welded — 92/100, better than 93% of steel grades
- Conducts heat well — 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades
Limitations
- Limited ductility — 13%, worse than 78% of steel grades
20# properties
Typical room-temperature values for 20#-CD; bars are the position among steel grades.
Physical3
20# has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F).
Mechanical14
20# has a yield strength of 395 MPa (57.3 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 63% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20# is rated for continuous service to 425°C (797 °F). It conducts heat at 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
20# conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 20# takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
20#'s machinability is good (65/100, better than 93% of steel grades); weldability excellent (92/100); formability good (60/100).
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. 20# is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20#
Is 20# easy to machine?
Free machining is limited by gummy low-carbon ferrite — use sharp positive-rake tools, high speeds and good coolant; cold-drawn bar cuts and finishes far better than hot-rolled or annealed stock.
Can 20# be welded?
Excellent weldability by all arc, resistance and gas processes with no preheat below ~25 mm (CE ≈ 0.3); use ER70S-6 / E4303-E5015 class consumables.
Can 20# be formed, bent or molded?
Very good cold formability — deep drawing, bending to tight radii and cold heading are routine in annealed or hot-rolled condition; hot working range ~850–1200 °C.
Manufacturability
The process limits FabDigit's quote engine applies to 20#. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better65 / 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 | Excellent60 / 100 |
|---|---|
| Weldability | Excellent92 / 100 |
20# 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 | 0.17 – 0.23 | 0.2 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.35 – 0.65 | 0.5 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Crresidual | ≤ 0.25 | 0.05 |
| Niresidual | ≤ 0.3 | 0.05 |
| Curesidual | ≤ 0.25 | 0.05 |
| Fe | balance |
What surface finishes work on 20#?
No anodizing; protect with zinc/electro-galvanizing, phosphate + oil, black oxide, hard chrome or paint — bare surfaces rust within days in humid air.
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 20# cost?
20# is a budget-cost steel ($), cheaper than about 100% 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.
20# — frequently asked
What is 20# used for?
20# is typically used for general fabrication, brackets and welded plate. In short: cold-drawn carbon plate.
What is the yield strength of 20#?
20# has a typical yield strength of 395 MPa (57.3 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 63% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 20# easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Free machining is limited by gummy low-carbon ferrite — use sharp positive-rake tools, high speeds and good coolant; cold-drawn bar cuts and finishes far better than hot-rolled or annealed stock.
Can 20# be welded?
Yes — weldability is rated excellent (92/100). Excellent weldability by all arc, resistance and gas processes with no preheat below ~25 mm (CE ≈ 0.3); use ER70S-6 / E4303-E5015 class consumables.
What surface finishes work on 20#?
No anodizing; protect with zinc/electro-galvanizing, phosphate + oil, black oxide, hard chrome or paint — bare surfaces rust within days in humid air.
Can 20# be formed, bent or molded?
Very good cold formability — deep drawing, bending to tight radii and cold heading are routine in annealed or hot-rolled condition; hot working range ~850–1200 °C.
What is the maximum service temperature of 20#?
20# is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 20#-CD and 20#-A?
CD is the default condition — default stock condition for small round bar, shafting and precision tube; best dimensional accuracy, surface finish and machinability. A: softest condition — pick for deep drawing, severe cold forming or stress relief before carburizing. Yield strength is 395 MPa in CD versus 250 MPa in A.
How much does 20# cost?
20# is a budget-cost steel ($), cheaper than about 100% 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 20#?
Yes — 20# 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
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.