Steel 1049-QT425
Heat-treated state
AISI/SAE 1049 · UNS G10490
QT425 = q&T
High-strength tempered martensite for highly loaded shafts, crankpins and bolts of moderate section.
Values for the QT425 condition
Other 1049 tempers and conditions
1049 is listed in 10 conditions; see the grade overview at 1049.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
HRDefault Hot rolled | Cheapest stock condition for forging blanks, shafts and parts that will be heat treated or machined later. | 340 | 620 | 20 | 179 HB | — |
Solution annealed | Softest condition — choose for maximum machinability, cold forming or before further heat treatment. | 365 | 636 | 24 | 187 HB | — |
Normalized | Uniform fine-pearlite structure with higher strength than hot rolled — standard condition for forged shafts and axles not requiring Q&T. | 427 | 748 | 20 | 217 HB | — |
Q&T | Maximum toughness/ductility of the Q&T range; use where impact and machining ease matter more than strength. | 434 | 653 | 24 | 187 HB | — |
Induction hardened | Select for wear surfaces on shafts, cams and sprocket teeth needing a hard skin over a tough normalized core. | 500 | 760 | 15 | 57 HRC | 10 % IACS |
Q&T | Balanced strength/toughness condition for general machinery shafts and axles; good machinability after treatment. | 538 | 717 | 20 | 18 HRC | — |
Annealed and Cold Drawn | Use when a cold-drawn bright bar is needed with better ductility and lower residual stress than straight cold drawing. | 565 | 655 | 12 | 187 HB | — |
Cold drawn | Pick for close tolerance, bright-finish bar with higher yield strength where no further heat treatment is planned. | 580 | 690 | 10 | 197 HB | — |
QT425This page Q&T | High-strength tempered martensite for highly loaded shafts, crankpins and bolts of moderate section. | 641 | 793 | 13.5 | 22 HRC | — |
Q&T | Maximum hardness and wear resistance for small sections (pins, wear plates); very low toughness, avoid impact loading. | 807 | 1,120 | 9 | 50 HRC | — |
What is 1049-QT425?
1049-QT425 is 1049 heat treated to QT425 — high-strength tempered martensite for highly loaded shafts, crankpins and bolts of moderate section. 1049-QT425 has a yield strength of 641 MPa (93 ksi) and a tensile strength of 793 MPa (115 ksi) — stronger than 79% of steel grades. Elongation at break is 13.5% and the elastic modulus is 200 GPa (29 Msi). 1049-QT425 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). HR is the default condition FabDigit quotes; QT425 is available on request or by drawing note.
Advantages
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Conducts heat well — 49.8 W/m·K (28.8 BTU/hr·ft·°F), better than 85% of steel grades
- High strength — 641 MPa (93 ksi), better than 79% of steel grades
Limitations
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 82% of steel grades
- Limited ductility — 13.5%, worse than 77% of steel grades
1049-QT425 properties
Typical room-temperature values for 1049-QT425; 11 are specific to this condition. Other listed values are 1049 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
1049-QT425 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).
Mechanical16
1049-QT425 has a yield strength of 641 MPa (93 ksi) and a tensile strength of 793 MPa (115 ksi) — stronger than 79% of steel grades. Elongation at break is 13.5% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1049-QT425 is rated for continuous service to 400°C (752 °F). It conducts heat at 49.8 W/m·K (28.8 BTU/hr·ft·°F), better than 85% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
1049-QT425 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 1049-QT425 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 28%.
Manufacturability8
1049-QT425's machinability is fair (42/100, worse than 73% of steel grades); weldability fair (35/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1049-QT425
Is 1049 easy to machine?
Machines best annealed or Q&T to 180–230 HB with carbide tooling and rigid setups; above 40 HRC switch to grinding or CBN.
Can 1049 be welded?
CE ≈ 0.6–0.7 — preheat 200–320 °C, use low-hydrogen electrodes and post-weld stress relief/temper to avoid HAZ cracking.
Can 1049 be formed, bent or molded?
Cold formability is limited; hot forge at 1100–1200 °C and normalize afterwards, or spheroidize-anneal before cold heading.
What surface finishes work on 1049?
No self-passivation — protect with paint, oil, zinc/manganese phosphate, black oxide, zinc or hard chrome plating; polishes well after hardening.
1049 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 |
|---|---|---|
| Cheat analysis, SAE J403 | 0.46 – 0.53 | 0.49 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.03 |
| Siwhen silicon-killed steel is specified | 0.15 – 0.35 | 0.25 |
| Fe | balance | — |
1049-QT425 — frequently asked
What is 1049-QT425 used for?
1049-QT425 is typically used for axles, shafts, forgings, couplings and machine parts. In short: forging-grade medium carbon; C50 / S50C equivalent; 20 % elongation as supplied.
What is the yield strength of 1049-QT425?
1049-QT425 has a typical yield strength of 641 MPa (93 ksi) and a tensile strength of 793 MPa (115 ksi) — stronger than 79% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 1049-QT425 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machines best annealed or Q&T to 180–230 HB with carbide tooling and rigid setups; above 40 HRC switch to grinding or CBN.
Can 1049-QT425 be welded?
With care — weldability is rated fair (35/100). CE ≈ 0.6–0.7 — preheat 200–320 °C, use low-hydrogen electrodes and post-weld stress relief/temper to avoid HAZ cracking.
What surface finishes work on 1049-QT425?
No self-passivation — protect with paint, oil, zinc/manganese phosphate, black oxide, zinc or hard chrome plating; polishes well after hardening.
Can 1049-QT425 be formed, bent or molded?
Cold formability is limited; hot forge at 1100–1200 °C and normalize afterwards, or spheroidize-anneal before cold heading.
What is the maximum service temperature of 1049-QT425?
1049-QT425 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 1049-HR and 1049-QT205?
HR is the default condition — cheapest stock condition for forging blanks, shafts and parts that will be heat treated or machined later. QT205: maximum hardness and wear resistance for small sections (pins, wear plates); very low toughness, avoid impact loading. Yield strength is 340 MPa in HR versus 807 MPa in QT205.
Sources
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASTM A108 — Steel Bar, Carbon and Alloy, Cold-Finished — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
- JIS G4051 — Carbon Steels for Machine Structural Use (S50C) — JISC (2016)
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.