Stainless Steel 40Kh13-QT400
Heat-treated state
EN 40Kh13 · AISI/SAE 420
QT400 = q&T 400–500 °C
Spring, blade-back and valve-plate condition; accept the reduced impact toughness of the 475 °C embrittlement window.
Values for the QT400 condition
Other 40Kh13 tempers and conditions
40Kh13 is listed in 8 conditions; see the grade overview at 40Kh13.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard stock condition for bar, strip and forging blanks — machine and form here, then harden. | 420 | 700 | 20 | 200 HB | — |
Hot rolled | Mill condition of hot bar and billet — hard and partly martensitic, normally annealed before machining. | 600 | 880 | 12 | 26 HRC | — |
Cold drawn | Choose for tight-tolerance ground/drawn bar and spring wire that will be hardened after machining. | 720 | 900 | 10 | 27 HRC | — |
Q&T 600–680 °C | Structural condition for shafts, valve stems and fasteners where toughness and machinability matter more than hardness. | 780 | 980 | 14 | 30 HRC | — |
Cold Rolled Hard strip | Precision strip supplied work-hardened for stamped blades and shims that are hardened after blanking. | 1,050 | 1,250 | 4 | 41 HRC | 2.8 % IACS |
QT400This page Q&T 400–500 °C | Spring, blade-back and valve-plate condition; accept the reduced impact toughness of the 475 °C embrittlement window. | 1,250 | 1,500 | 8 | 46 HRC | — |
Q&T 150–300 °C | The cutlery / surgical-instrument condition: maximum hardness, edge retention and corrosion resistance after polishing. | 1,450 | 1,750 | 5 | 51 HRC | — |
As-Quenched | Intermediate condition only — must be tempered or stress-relieved immediately to avoid quench cracking. | 1,550 | 1,950 | 2 | 55 HRC | — |
What is 40Kh13-QT400?
40Kh13-QT400 is 40Kh13 heat treated to QT400 — spring, blade-back and valve-plate condition; accept the reduced impact toughness of the 475 °C embrittlement window. 40Kh13-QT400 has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 215 GPa (31.2 Msi). 40Kh13-QT400 has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,425°C (2,597 °F). A is the default condition FabDigit quotes; QT400 is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 88/100, better than 100% of stainless steel grades
- High strength — 1,250 MPa (181 ksi), better than 99% of stainless steel grades
- Conducts heat well — 28.5 W/m·K (16.5 BTU/hr·ft·°F), better than 97% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
Limitations
- Limited ductility — 8%, worse than 99% of stainless steel grades
- Low fracture toughness — 28 MPa·√m (25.5 ksi·√in), worse than 99% of stainless steel grades
- Difficult to machine — 18/100, worse than 99% of stainless steel grades
- Difficult to weld — 25/100, worse than 92% of stainless steel grades
- Needs corrosion protection — 48/100, worse than 80% of stainless steel grades
40Kh13-QT400 properties
Typical room-temperature values for 40Kh13-QT400; 15 are specific to this condition. Other listed values are 40Kh13 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
40Kh13-QT400 has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
40Kh13-QT400 has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
40Kh13-QT400 is rated for continuous service to 400°C (752 °F). It conducts heat at 28.5 W/m·K (16.5 BTU/hr·ft·°F), better than 97% of stainless steel grades. Thermal expansion is 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
40Kh13-QT400 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of 40Kh13-QT400 takes about 53 MJ of energy and emits 4.5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
40Kh13-QT400's machinability is poor (18/100, worse than 99% of stainless steel grades); weldability poor (25/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 40Kh13-QT400
Is 40Kh13 easy to machine?
Machine in the annealed state with sharp, positive-rake carbide, rigid setups and generous coolant; above ~40 HRC switch to grinding, CBN or EDM.
Can 40Kh13 be welded?
Poor weldability — preheat 200–300 °C, use 410NiMo or austenitic filler, and temper/anneal immediately after welding to avoid cracks in the hard HAZ.
Can 40Kh13 be formed, bent or molded?
Cold form only in the annealed condition with generous bend radii (≥2t); hot work at 1100–850 °C followed by slow cooling and full anneal.
What surface finishes work on 40Kh13?
Harden and temper before final polishing, then passivate in nitric or citric acid; hard chrome, PVD or black oxide are common on cutlery and instruments.
40Kh13 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 | 0.36 – 0.45 | 0.4 |
| Si | ≤ 0.8 | 0.4 |
| Mn | ≤ 0.8 | 0.4 |
| Cr | 12 – 14 | 13 |
| Niresidual | ≤ 0.6 | — |
| Tiresidual | ≤ 0.2 | — |
| Curesidual | ≤ 0.3 | — |
| S | ≤ 0.03 | — |
| P | ≤ 0.03 | — |
| Fe | balance | — |
40Kh13-QT400 — frequently asked
What is 40Kh13-QT400 used for?
40Kh13-QT400 is typically used for surgical instruments, cutlery, springs and measuring tools. In short: hardenable 420-type stainless; edge-holding instrument grade; poor weldability.
What is the yield strength of 40Kh13-QT400?
40Kh13-QT400 has a typical yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 99% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 40Kh13-QT400 easy to machine?
Not especially — machinability is rated poor (18/100, worse than 99% of stainless steel grades). Machine in the annealed state with sharp, positive-rake carbide, rigid setups and generous coolant; above ~40 HRC switch to grinding, CBN or EDM.
Can 40Kh13-QT400 be welded?
Not readily — weldability is rated poor (25/100). Poor weldability — preheat 200–300 °C, use 410NiMo or austenitic filler, and temper/anneal immediately after welding to avoid cracks in the hard HAZ.
What surface finishes work on 40Kh13-QT400?
Harden and temper before final polishing, then passivate in nitric or citric acid; hard chrome, PVD or black oxide are common on cutlery and instruments.
Can 40Kh13-QT400 be formed, bent or molded?
Cold form only in the annealed condition with generous bend radii (≥2t); hot work at 1100–850 °C followed by slow cooling and full anneal.
What is the maximum service temperature of 40Kh13-QT400?
40Kh13-QT400 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 40Kh13-A and 40Kh13-Q?
A is the default condition — standard stock condition for bar, strip and forging blanks — machine and form here, then harden. Q: intermediate condition only — must be tempered or stress-relieved immediately to avoid quench cracking. Yield strength is 420 MPa in A versus 1,550 MPa in Q.
Sources
- GOST 5632-2014 Stainless steels and corrosion-resistant alloys — grades — Rosstandart (2014)
- GOST 5949-2018 Corrosion-resistant, heat-resistant steel bars and sections — Rosstandart (2018)
- GB/T 1220 (40Cr13) — SAC (2007)
- ASTM A276/A276M Stainless Steel Bars and Shapes (UNS S42000) — ASTM (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Marochnik stali i splavov — 40Х13 physical and mechanical data — Marochnik (2020)
- 1.4034 / X46Cr13 martensitic stainless datasheet — Böhler / Outokumpu (2021)
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.