Steel 15Kh Q&T (Quenched and tempered)
Heat-treated state · default condition
GOST 15Kh (15Х)
The GOST 4543 acceptance condition — use these numbers for the core of small hardened parts and for through-hardened pins.
Values for the Q&T condition
Other 15Kh tempers and conditions
15Kh is listed in 6 conditions; see the grade overview at 15Kh.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — choose for deep machining, cold heading or cold extrusion before carburizing. | 300 | 490 | 28 | 160 HB | — |
Hot rolled | Mill delivery condition for bar and billet that will be machined and then carburized. | 330 | 540 | 24 | 170 HB | — |
Normalized | Uniform fine-grain structure with better machined-surface finish than annealed; standard pre-carburizing condition. | 350 | 560 | 22 | 11 HRC | 9 % IACS |
Cold drawn | Bright, close-tolerance bar for pins, bushings and shafts machined with minimal stock removal. | 520 | 640 | 12 | 200 HB | — |
Q&TDefaultThis page Quenched and tempered | The GOST 4543 acceptance condition — use these numbers for the core of small hardened parts and for through-hardened pins. | 540 | 750 | 14 | 20 HRC | — |
Carburized + quenched + 180 °C temper | Final service condition for gears and pins: hard wear-resistant case (0.5–1.2 mm) over a tough medium-strength core. | 590 | 800 | 12 | 58 HRC | — |
What is 15Kh Q&T?
15Kh Q&T is 15Kh heat treated to Q&T — the GOST 4543 acceptance condition — use these numbers for the core of small hardened parts and for through-hardened pins. 15Kh Q&T has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 70% of steel grades. Elongation at break is 14% and the elastic modulus is 212 GPa (30.7 Msi). 15Kh Q&T has a density of 7.82 g/cm³ (0.283 lb/in³), lighter than 82% of steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
15Kh Q&T properties
Typical room-temperature values for 15Kh Q&T; 13 are specific to this condition. Other listed values are 15Kh reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
15Kh Q&T has a density of 7.82 g/cm³ (0.283 lb/in³), lighter than 82% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical15
15Kh Q&T has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 70% of steel grades. Elongation at break is 14% and the elastic modulus is 212 GPa (30.7 Msi).
Thermal6
15Kh Q&T is rated for continuous service to 200°C (392 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
15Kh Q&T conducts electricity at 8.2 % IACS, better than 61% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 15Kh Q&T takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
15Kh Q&T's machinability is fair (45/100, worse than 65% of steel grades); weldability good (55/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 15Kh Q&T
Is 15Kh easy to machine?
Machine in the annealed or normalized state (≈60–65 % of AISI 1212); leave 0.1–0.3 mm grinding stock for post-carburizing finishing.
Can 15Kh be welded?
Weldable with low-hydrogen electrodes at 150–250 °C preheat plus post-weld stress relief; do not weld carburized surfaces.
Can 15Kh be formed, bent or molded?
Good hot forgeability at 1150–850 °C and acceptable cold upsetting when spheroidize annealed; normalize after forging.
What surface finishes work on 15Kh?
No anodizing — protect with phosphating and oil, black oxide, or zinc/nickel plating; ground and honed case surfaces give best fatigue life.
15Kh 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 | 0.12 – 0.18 | 0.15 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.4 – 0.7 | 0.55 |
| Cr | 0.7 – 1 | 0.85 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| Simpurity | ≤ 0.04 | — |
| Pimpurity | ≤ 0.04 | — |
| Fe | balance | — |
15Kh Q&T — frequently asked
What is 15Kh Q&T used for?
15Kh Q&T is typically used for lightly loaded small gears, pins and pivot pins, small shafts and spindles, bushings, cams and levers and sprockets. In short: entry-level chromium case steel; low-cost carburizing grade; weldable before carburizing.
What is the yield strength of 15Kh Q&T?
15Kh Q&T has a typical yield strength of 540 MPa (78.3 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 70% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 15Kh Q&T easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed or normalized state (≈60–65 % of AISI 1212); leave 0.1–0.3 mm grinding stock for post-carburizing finishing.
Can 15Kh Q&T be welded?
Yes — weldability is rated good (55/100). Weldable with low-hydrogen electrodes at 150–250 °C preheat plus post-weld stress relief; do not weld carburized surfaces.
What surface finishes work on 15Kh Q&T?
No anodizing — protect with phosphating and oil, black oxide, or zinc/nickel plating; ground and honed case surfaces give best fatigue life.
Can 15Kh Q&T be formed, bent or molded?
Good hot forgeability at 1150–850 °C and acceptable cold upsetting when spheroidize annealed; normalize after forging.
What is the maximum service temperature of 15Kh Q&T?
15Kh Q&T is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 15Kh Q&T and 15Kh-A?
Q&T is the default condition — the GOST 4543 acceptance condition — use these numbers for the core of small hardened parts and for through-hardened pins. A: softest condition — choose for deep machining, cold heading or cold extrusion before carburizing. Yield strength is 540 MPa in Q&T versus 300 MPa in A.
Sources
- GOST 4543 — Alloyed structural steel bars — Gosstandart / Rosstandart (2016)
- GB/T 3077 (15Cr equivalent) — SAC (2015)
- Marochnik Stali i Splavov — grade 15Kh property tables — Marochnik (2020)
- ASM Handbook Vol.1 & Vol.4 — carburizing low-alloy steels — ASM International (1991)
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.