Steel Y40Mn QT-25-30HRC
Hardness band
General-purpose quench-and-temper level for medium-duty shafts, studs and levers that still machine easily.
Values for the QT-25-30HRC condition
Other Y40Mn tempers and conditions
Y40Mn is listed in 7 conditions; see the grade overview at Y40Mn.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Choose when maximum dimensional stability and lowest residual stress before finish machining are needed. | 330 | 570 | 20 | 170 HB | 9.5 % IACS |
Hot rolled | Cheapest stock form for large-diameter bar that will be fully machined or subsequently heat treated. | 380 | 620 | 16 | 185 HB | 9.5 % IACS |
Normalized | Uniform fine pearlitic structure for better strength/toughness balance in as-machined shafts. | 410 | 700 | 17 | 207 HB | 9 % IACS |
CDDefault Cold drawn | Standard stocked condition: tight tolerance bright bar with the best chip control for high-volume CNC turning. | 540 | 660 | 10 | 195 HB | — |
QT-25-30HRCThis page oil quenched and high tempered | General-purpose quench-and-temper level for medium-duty shafts, studs and levers that still machine easily. | 700 | 880 | 14 | 28 HRC | — |
Induction hardened | Use when a wear-resistant 50+ HRC bearing/journal surface is needed on a tough machined core. | 720 | 900 | 12 | 54 HRC | 8.5 % IACS |
oil quenched and medium tempered | Higher-strength condition for loaded pins, spindles and Grade-5-class fasteners; toughness starts to drop. | 850 | 1,030 | 12 | 33 HRC | — |
What is Y40Mn QT-25-30HRC?
Y40Mn QT-25-30HRC is Y40Mn heat treated to QT-25-30HRC — general-purpose quench-and-temper level for medium-duty shafts, studs and levers that still machine easily. Y40Mn QT-25-30HRC has a yield strength of 700 MPa (102 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 81% of steel grades. Elongation at break is 14% and the elastic modulus is 207 GPa (30 Msi). Y40Mn QT-25-30HRC 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). CD is the default condition FabDigit quotes; QT-25-30HRC is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Easy to machine — 62/100, better than 89% of steel grades
- High strength — 700 MPa (102 ksi), better than 81% of steel grades
Limitations
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 86% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
Y40Mn QT-25-30HRC properties
Typical room-temperature values for Y40Mn QT-25-30HRC; 10 are specific to this condition. Other listed values are Y40Mn reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Y40Mn QT-25-30HRC 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
Y40Mn QT-25-30HRC has a yield strength of 700 MPa (102 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 81% of steel grades. Elongation at break is 14% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
Y40Mn QT-25-30HRC is rated for continuous service to 400°C (752 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
Y40Mn QT-25-30HRC conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of Y40Mn QT-25-30HRC takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 35%.
Manufacturability6
Y40Mn QT-25-30HRC's machinability is good (62/100, better than 89% of steel grades); weldability poor (28/100); formability poor (28/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Y40Mn QT-25-30HRC
Is Y40Mn easy to machine?
Excellent turning/drilling with short chips; run 15–25 % higher speed than 1045, keep feeds high so MnS lubrication works, and avoid very light finishing passes that smear the surface.
Can Y40Mn be welded?
Poor — high sulfur plus ~0.4 % C promotes hot cracking and porosity; if unavoidable, preheat 200–250 °C, use low-hydrogen filler and post-weld stress relief, and never use it in fatigue-loaded welded joints.
Can Y40Mn be formed, bent or molded?
Hot forge at 1100–1200 °C (never below ~850 °C); cold heading and bending are limited by sulfide anisotropy — bend transverse to the rolling direction with generous radii.
What surface finishes work on Y40Mn?
Takes zinc, black oxide, phosphate and hard chrome well, but sulfide stringers can pit during acid pickling and leave streaks after polishing; degrease thoroughly and prefer alkaline cleaning.
Y40Mn 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 | 0.37 – 0.45 | 0.41 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 1.2 – 1.55 | 1.38 |
| Sresulfurized for chip breaking (MnS inclusions) | 0.18 – 0.3 | 0.24 |
| P | ≤ 0.06 | 0.03 |
| Crresidual | ≤ 0.25 | — |
| Niresidual | ≤ 0.25 | — |
| Curesidual | ≤ 0.25 | — |
| Fe | balance | — |
Y40Mn QT-25-30HRC — frequently asked
What is Y40Mn QT-25-30HRC used for?
Y40Mn QT-25-30HRC is typically used for shafts, axles and high-strength bolts. In short: highest-strength Mn free-cutting bar; quench-and-temper to 35 HRC; 1140 equivalent stock.
What is the yield strength of Y40Mn QT-25-30HRC?
Y40Mn QT-25-30HRC has a typical yield strength of 700 MPa (102 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 81% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is Y40Mn QT-25-30HRC easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Excellent turning/drilling with short chips; run 15–25 % higher speed than 1045, keep feeds high so MnS lubrication works, and avoid very light finishing passes that smear the surface.
Can Y40Mn QT-25-30HRC be welded?
Not readily — weldability is rated poor (28/100). Poor — high sulfur plus ~0.4 % C promotes hot cracking and porosity; if unavoidable, preheat 200–250 °C, use low-hydrogen filler and post-weld stress relief, and never use it in fatigue-loaded welded joints.
What surface finishes work on Y40Mn QT-25-30HRC?
Takes zinc, black oxide, phosphate and hard chrome well, but sulfide stringers can pit during acid pickling and leave streaks after polishing; degrease thoroughly and prefer alkaline cleaning.
Can Y40Mn QT-25-30HRC be formed, bent or molded?
Hot forge at 1100–1200 °C (never below ~850 °C); cold heading and bending are limited by sulfide anisotropy — bend transverse to the rolling direction with generous radii.
What is the maximum service temperature of Y40Mn QT-25-30HRC?
Y40Mn QT-25-30HRC 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 Y40Mn-CD and Y40Mn-ANN?
CD is the default condition — standard stocked condition: tight tolerance bright bar with the best chip control for high-volume CNC turning. ANN: choose when maximum dimensional stability and lowest residual stress before finish machining are needed. Yield strength is 540 MPa in CD versus 330 MPa in ANN.
Sources
- GB/T 8731 (Free-cutting structural steel) — SAC / (2008)
- GB/T 699 (reference for heat treatment/mechanicals) — SAC (2015)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels — ASM International (1990)
- ASM Handbook Vol. 16: Machining — ASM International (1989)
- SAE J403 / ASTM A29 (grade 1140 analog composition) — SAE / ASTM (2019)
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.