Steel 1335-QT425
Heat-treated state
AISI/SAE 1335 · UNS G13350
QT425 = q&T 425 °C
Balanced strength/toughness level used for heavily loaded shafts, spindles and bolts.
Values for the QT425 condition
Other 1335 tempers and conditions
1335 is listed in 12 conditions; see the grade overview at 1335.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot rolled | Cheapest mill condition for parts that will be fully heat treated after rough machining. | 415 | 690 | 22 | 200 HB | — |
Solution annealed | Softest condition, chosen for deep machining, cold forming or before re-hardening. | 440 | 675 | 26 | 190 HB | — |
NDefault Normalized | Standard stock condition for medium-strength shafts and forgings needing uniform structure and good toughness without Q&T. | 540 | 810 | 23 | 21 HRC | — |
Q&T 650 °C | Softest Q&T level; maximum toughness and machinability where only moderate strength is needed. | 600 | 780 | 23 | 21 HRC | — |
Cold drawn | Pick for tight tolerance, bright finish shafting where higher yield and better chip control are wanted without heat treatment. | 650 | 760 | 12 | 223 HB | — |
Induction hardened | Use when a tough Q&T core must carry the load while journals or splines need 50+ HRC wear resistance. | 820 | 960 | 16 | 55 HRC | 7.5 % IACS |
Q&T 540 °C | Standard tough condition (~30 HRC) for drive shafts and forged levers subject to impact. | 830 | 960 | 18 | 30 HRC | — |
quenched and tempered to hardness band | Common purchase specification for machined shafts and gear blanks bought heat treated to a hardness window. | 830 | 965 | 18 | 30 HRC | — |
QT425This page Q&T 425 °C | Balanced strength/toughness level used for heavily loaded shafts, spindles and bolts. | 1,080 | 1,180 | 15 | 38 HRC | — |
quenched and tempered to hardness band | Higher-strength purchased condition for wear-loaded pins, sprockets and small shafts in thin sections. | 1,110 | 1,240 | 14 | 40 HRC | — |
Q&T 315 °C | High strength with slightly better ductility than 205 °C temper; avoid this range if temper embrittlement is a concern. | 1,340 | 1,480 | 13 | 45 HRC | — |
Q&T 205 °C | Maximum hardness and strength for wear parts; low ductility and notch sensitivity, rarely used on large sections. | 1,450 | 1,690 | 12 | 49 HRC | — |
What is 1335-QT425?
1335-QT425 is 1335 heat treated to QT425 — balanced strength/toughness level used for heavily loaded shafts, spindles and bolts. 1335-QT425 has a yield strength of 1,080 MPa (157 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 93% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi). 1335-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). N is the default condition FabDigit quotes; QT425 is available on request or by drawing note.
Advantages
- High strength — 1,080 MPa (157 ksi), better than 93% of steel grades
Limitations
- Difficult to machine — 36/100, worse than 81% of steel grades
1335-QT425 properties
Typical room-temperature values for 1335-QT425; 13 are specific to this condition. Other listed values are 1335 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
1335-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
1335-QT425 has a yield strength of 1,080 MPa (157 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 93% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
1335-QT425 is rated for continuous service to 350°C (662 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
1335-QT425 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 1335-QT425 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability8
1335-QT425's machinability is fair (36/100, worse than 81% of steel grades); weldability fair (40/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1335-QT425
Is 1335 easy to machine?
Machines best annealed or normalized (~190–235 HB) at roughly 60 % of 1212 speed; above 35 HRC use coated carbide, rigid setups and reduced feeds.
Can 1335 be welded?
Carbon equivalent ~0.65–0.70, so preheat 200–300 °C, use low-hydrogen consumables and temper after welding; avoid welding in the fully hardened state.
Can 1335 be formed, bent or molded?
Hot forge 1100–1200 °C and normalize afterwards; cold bending is limited — anneal first and allow generous bend radii.
What surface finishes work on 1335?
No inherent corrosion resistance: specify phosphate + oil, black oxide, zinc or hard-chrome plating; bake after plating to avoid hydrogen embrittlement above ~1000 MPa.
1335 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 | 0.33 – 0.38 | 0.36 |
| Mnprimary alloying addition for hardenability | 1.6 – 1.9 | 1.75 |
| Sideoxidizer; not required for some product forms | 0.15 – 0.35 | 0.25 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
1335-QT425 — frequently asked
What is 1335-QT425 used for?
1335-QT425 is typically used for shafts, forgings, medium-strength fasteners and gears. In short: mn-only alloy hardenability; cheaper than 4140; weldable with preheat.
What is the yield strength of 1335-QT425?
1335-QT425 has a typical yield strength of 1,080 MPa (157 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 1335-QT425 easy to machine?
Not especially — machinability is rated fair (36/100, worse than 81% of steel grades). Machines best annealed or normalized (~190–235 HB) at roughly 60 % of 1212 speed; above 35 HRC use coated carbide, rigid setups and reduced feeds.
Can 1335-QT425 be welded?
With care — weldability is rated fair (40/100). Carbon equivalent ~0.65–0.70, so preheat 200–300 °C, use low-hydrogen consumables and temper after welding; avoid welding in the fully hardened state.
What surface finishes work on 1335-QT425?
No inherent corrosion resistance: specify phosphate + oil, black oxide, zinc or hard-chrome plating; bake after plating to avoid hydrogen embrittlement above ~1000 MPa.
Can 1335-QT425 be formed, bent or molded?
Hot forge 1100–1200 °C and normalize afterwards; cold bending is limited — anneal first and allow generous bend radii.
What is the maximum service temperature of 1335-QT425?
1335-QT425 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1335-N and 1335-QT205?
N is the default condition — standard stock condition for medium-strength shafts and forgings needing uniform structure and good toughness without Q&T. QT205: maximum hardness and strength for wear parts; low ductility and notch sensitivity, rarely used on large sections. Yield strength is 540 MPa in N versus 1,450 MPa in QT205.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- 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)
- GB/T 3077 (35Mn2 comparable grade) — SAC (2015)
- Mysteel / SMM (2025)
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.