Stainless Steel 1.4024 +QT550
Heat-treated state
EN 1.4024
+QT550 = quenched and tempered to 550 MPa minimum tensile class
High-temperature tempered condition for shafts and fittings needing maximum toughness and ductility with moderate strength.
Values for the +QT550 condition
Other 1.4024 tempers and conditions
1.4024 is listed in 4 conditions; see the grade overview at 1.4024.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ADefault Annealed | Standard stocked bar condition for machining, forming and subsequent hardening by the fabricator. | 300 | 530 | 25 | 175 HB | — |
+QT550This page Quenched and tempered to 550 MPa minimum tensile class | High-temperature tempered condition for shafts and fittings needing maximum toughness and ductility with moderate strength. | 400 | 620 | 20 | 190 HB | — |
Quenched and tempered to 650 MPa minimum tensile class | Standard engineering condition for pump shafts, valve stems and fasteners needing higher strength with still-acceptable impact values. | 500 | 720 | 17 | 21 HRC | — |
Hardened and low-temperature tempered | Choose for wear parts, cutlery blanks and small tooling where hardness and edge retention outweigh toughness. | 1,050 | 1,350 | 10 | 43 HRC | — |
What is 1.4024 +QT550?
1.4024 +QT550 is 1.4024 heat treated to +QT550 — high-temperature tempered condition for shafts and fittings needing maximum toughness and ductility with moderate strength. 1.4024 +QT550 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 215 GPa (31.2 Msi). 1.4024 +QT550 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F). +A is the default condition FabDigit quotes; +QT550 is available on request or by drawing note.
Advantages
- Conducts heat well — 30 W/m·K (17.3 BTU/hr·ft·°F), better than 99% of stainless steel grades
- Low embodied carbon — 3 kg CO₂/kg, better than 97% of stainless steel grades
- Easy to machine — 52/100, better than 91% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
Limitations
- Needs corrosion protection — 38/100, worse than 95% of stainless steel grades
- Difficult to weld — 35/100, worse than 86% of stainless steel grades
- Low fracture toughness — 70 MPa·√m (63.7 ksi·√in), worse than 83% of stainless steel grades
- Limited ductility — 20%, worse than 79% of stainless steel grades
1.4024 +QT550 properties
Typical room-temperature values for 1.4024 +QT550; 19 are specific to this condition. Other listed values are 1.4024 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4024 +QT550 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
1.4024 +QT550 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
1.4024 +QT550 is rated for continuous service to 500°C (932 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), better than 99% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
1.4024 +QT550 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 95% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4024 +QT550 takes about 42 MJ of energy and emits 3 kg of CO₂ — less than 95% of stainless steel grades. Typical recycled content is 65%.
Manufacturability6
1.4024 +QT550's machinability is fair (52/100, better than 91% of stainless 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 1.4024 +QT550
Is 1.4024 easy to machine?
Machine in the annealed or ≤250 HB tempered condition with sharp, rigid tooling, positive rake and generous coolant; the alloy work-hardens moderately and forms stringy chips, so free-machining sulphurised grades are preferred for screw-machine work.
Can 1.4024 be welded?
Weldable with matched 13Cr or austenitic 309/308L filler, but preheat to 200–300 °C and post-weld temper at 700–750 °C are needed to avoid hard, crack-prone martensite in the HAZ.
Can 1.4024 be formed, bent or molded?
Cold bending and light forming only in the annealed state with generous radii; hot working at 1100–850 °C followed by slow cooling and full anneal gives the best results.
What surface finishes work on 1.4024?
Takes a fine mechanical polish and is best passivated in nitric acid after hardening; hard chrome, nitriding or PVD coatings are used where wear or chloride exposure exceeds the base alloy's capability.
1.4024 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 |
|---|---|---|
| CEN 10088-3 X15Cr13 | 0.12 – 0.17 | 0.15 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1 | 0.5 |
| P | ≤ 0.04 | 0.03 |
| Sfree-machining variants use higher S | ≤ 0.03 | 0.02 |
| Cr | 12 – 14 | 13 |
| Niresidual, some standards limit to 0.75 | ≤ 0.75 | 0.3 |
| Fe | balance | — |
1.4024 +QT550 — frequently asked
What is 1.4024 +QT550 used for?
1.4024 +QT550 is typically used for turbine blades, valve components and shafts. In short: toughness-biased 13% Cr grade; better machining than 1.4021; lowest corrosion rating of trio.
What is the yield strength of 1.4024 +QT550?
1.4024 +QT550 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 57% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 1.4024 +QT550 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 91% of stainless steel grades). Machine in the annealed or ≤250 HB tempered condition with sharp, rigid tooling, positive rake and generous coolant; the alloy work-hardens moderately and forms stringy chips, so free-machining sulphurised grades are preferred for screw-machine work.
Can 1.4024 +QT550 be welded?
With care — weldability is rated fair (35/100). Weldable with matched 13Cr or austenitic 309/308L filler, but preheat to 200–300 °C and post-weld temper at 700–750 °C are needed to avoid hard, crack-prone martensite in the HAZ.
What surface finishes work on 1.4024 +QT550?
Takes a fine mechanical polish and is best passivated in nitric acid after hardening; hard chrome, nitriding or PVD coatings are used where wear or chloride exposure exceeds the base alloy's capability.
Can 1.4024 +QT550 be formed, bent or molded?
Cold bending and light forming only in the annealed state with generous radii; hot working at 1100–850 °C followed by slow cooling and full anneal gives the best results.
What is the maximum service temperature of 1.4024 +QT550?
1.4024 +QT550 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10088-3 Stainless steels — Semi-finished products, bars, rods, wire and sections — CEN (2014)
- EN 10088-1 Stainless steels — List of stainless steels (physical properties) — CEN (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- GB/T 1220 (2Cr13/1Cr13 comparison grades) — SAC (2007)
- Martensitic stainless bar datasheets (Outokumpu / Sandvik / Böhler 13Cr grades) — various producers (2023)
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.