Steel Y20-QT (Quenched and tempered)
Heat-treated state
GB Y20
Use for small-section shafts and fasteners that need higher strength with reasonable toughness.
Values for the QT condition
Other Y20 tempers and conditions
Y20 is listed in 7 conditions; see the grade overview at Y20.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest state; choose when maximum ductility or minimum residual stress before deep machining is needed. | 260 | 450 | 28 | 135 HB | — |
Hot rolled | Cheapest form for large-diameter bar that will be fully machined or later heat treated. | 285 | 500 | 24 | 150 HB | — |
Normalized | Uniform fine pearlitic structure; used to refine grain after forging and improve machined surface finish. | 300 | 490 | 25 | 148 HB | 10.5 % IACS |
Cold Drawn + Stress Relieved | Pick when long slender parts must stay straight after heavy asymmetric machining. | 410 | 540 | 16 | 170 HB | 10 % IACS |
QTThis page Quenched and tempered | Use for small-section shafts and fasteners that need higher strength with reasonable toughness. | 440 | 620 | 20 | 190 HB | 9.8 % IACS |
CDDefault Cold drawn | Standard stocked condition: tight tolerance bright bar with the best chip control and surface finish on automatic lathes. | 450 | 570 | 12 | 180 HB | — |
Carburized and hardened | Choose when the machined part needs a hard wear surface (pins, bushings, small gears) over a tough low-carbon core. | 480 | 700 | 12 | 59 HRC | 9.5 % IACS |
What is Y20-QT?
Y20-QT is Y20 heat treated to QT — use for small-section shafts and fasteners that need higher strength with reasonable toughness. Y20-QT has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 50% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi). Y20-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). CD is the default condition FabDigit quotes; QT is available on request or by drawing note.
Advantages
- Easy to machine — 70/100, better than 96% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 9.8 % IACS, better than 78% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
Y20-QT properties
Typical room-temperature values for Y20-QT; 21 are specific to this condition. Other listed values are Y20 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Y20-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).
Mechanical15
Y20-QT has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 50% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
Y20-QT is rated for continuous service to 450°C (842 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
Y20-QT conducts electricity at 9.8 % IACS, better than 78% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (9/100), worse than 98% of steel grades.
Sustainability4
Producing a kilogram of Y20-QT takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
Y20-QT's machinability is very good (70/100, better than 96% of steel grades); weldability poor (30/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Y20-QT
Is Y20 easy to machine?
Excellent chip breaking on screw machines — run 20–30% higher speed than 1045; carbide at 150–250 m/min, HSS 30–45 m/min, light cuts risk built-up edge so keep feed ≥0.05 mm/rev.
Can Y20 be welded?
Not recommended for structural welds; high sulfur causes hot cracking and porosity — if unavoidable use low-hydrogen basic electrodes, preheat 100–150 °C and low heat input.
Can Y20 be formed, bent or molded?
Suitable for light bending and machining of hot/cold worked bar; avoid severe cold heading or transverse bending because MnS stringers split the material along the rolling direction.
What surface finishes work on Y20?
Bare surface rusts quickly — protect with oil, black oxide, phosphating, zinc or nickel plating; sulfide inclusions cause pinholes in bright plating and pullout in mirror polishing.
Y20 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 8731-2008 | 0.17 – 0.25 | 0.21 |
| Si | 0.15 – 0.35 | 0.25 |
| Mnbinds S as MnS | 0.7 – 1 | 0.85 |
| Sfree-machining addition | 0.08 – 0.15 | 0.11 |
| P | ≤ 0.06 | 0.03 |
| Crresidual | ≤ 0.15 | — |
| Niresidual | ≤ 0.25 | — |
| Curesidual | ≤ 0.25 | — |
| Fe | balance | — |
Y20-QT — frequently asked
What is Y20-QT used for?
Y20-QT is typically used for shafts, gears and carburized parts. In short: most formable Y-series grade; case-hardenable free-cutting bar; machinability score 78.
What is the yield strength of Y20-QT?
Y20-QT has a typical yield strength of 440 MPa (63.8 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 50% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is Y20-QT easy to machine?
Yes — machinability is rated very good (70/100, better than 96% of steel grades). Excellent chip breaking on screw machines — run 20–30% higher speed than 1045; carbide at 150–250 m/min, HSS 30–45 m/min, light cuts risk built-up edge so keep feed ≥0.05 mm/rev.
Can Y20-QT be welded?
Not readily — weldability is rated poor (30/100). Not recommended for structural welds; high sulfur causes hot cracking and porosity — if unavoidable use low-hydrogen basic electrodes, preheat 100–150 °C and low heat input.
What surface finishes work on Y20-QT?
Bare surface rusts quickly — protect with oil, black oxide, phosphating, zinc or nickel plating; sulfide inclusions cause pinholes in bright plating and pullout in mirror polishing.
Can Y20-QT be formed, bent or molded?
Suitable for light bending and machining of hot/cold worked bar; avoid severe cold heading or transverse bending because MnS stringers split the material along the rolling direction.
What is the maximum service temperature of Y20-QT?
Y20-QT is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Y20-CD and Y20-A?
CD is the default condition — standard stocked condition: tight tolerance bright bar with the best chip control and surface finish on automatic lathes. A: softest state; choose when maximum ductility or minimum residual stress before deep machining is needed. Yield strength is 450 MPa in CD versus 260 MPa in A.
Sources
- SAE J403 / ASTM A29 — Resulfurized carbon steels (1117, 1118) — SAE / ASTM (2019)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels — ASM International (1990)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- Mysteel / 1688 (2026)
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.