Stainless Steel 1.4935 +QT900
Heat-treated state
EN 1.4935
+QT900 = quenched and tempered, Rm 900–1050 MPa class
Lower-tempered, highest-strength condition used mainly for pressure-vessel and turbine bolting per EN 10269; toughness and relaxation margins are tighter.
Values for the +QT900 condition
Other 1.4935 tempers and conditions
1.4935 is listed in 4 conditions; see the grade overview at 1.4935.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for rough machining, cold straightening or further hot work before final quench-and-temper. | 480 | 720 | 20 | 20 HRC | — |
Quenched and tempered, Rm 700–850 MPa class | Higher-tempered condition: pick when toughness and long-term creep ductility at 550–600 °C matter more than room-temperature strength. | 560 | 770 | 18 | 22 HRC | — |
+QT800Default Quenched and tempered, Rm 800–950 MPa class | Standard supply condition for turbine blades, rotors and high-temperature bolting: best balance of creep strength, yield strength and 27 J minimum toughness. | 660 | 865 | 16 | 26 HRC | — |
+QT900This page Quenched and tempered, Rm 900–1050 MPa class | Lower-tempered, highest-strength condition used mainly for pressure-vessel and turbine bolting per EN 10269; toughness and relaxation margins are tighter. | 760 | 960 | 14 | 31 HRC | — |
What is 1.4935 +QT900?
1.4935 +QT900 is 1.4935 heat treated to +QT900 — lower-tempered, highest-strength condition used mainly for pressure-vessel and turbine bolting per EN 10269; toughness and relaxation margins are tighter. 1.4935 +QT900 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 960 MPa (139 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 216 GPa (31.3 Msi). 1.4935 +QT900 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F). +QT800 is the default condition FabDigit quotes; +QT900 is available on request or by drawing note.
Advantages
- Low embodied carbon — 3.2 kg CO₂/kg, better than 95% of stainless steel grades
- High strength — 760 MPa (110 ksi), better than 94% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- Conducts heat well — 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades
Limitations
- Difficult to weld — 24/100, worse than 93% of stainless steel grades
- Limited formability — 12/100, worse than 93% of stainless steel grades
- Limited ductility — 14%, worse than 91% of stainless steel grades
- Needs corrosion protection — 45/100, worse than 85% of stainless steel grades
- Low fracture toughness — 80 MPa·√m (72.8 ksi·√in), worse than 79% of stainless steel grades
1.4935 +QT900 properties
Typical room-temperature values for 1.4935 +QT900; 15 are specific to this condition. Other listed values are 1.4935 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4935 +QT900 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
1.4935 +QT900 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 960 MPa (139 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 216 GPa (31.3 Msi).
Thermal6
1.4935 +QT900 is rated for continuous service to 560°C (1,040 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
1.4935 +QT900 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 85% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4935 +QT900 takes about 48 MJ of energy and emits 3.2 kg of CO₂ — less than 85% of stainless steel grades. Typical recycled content is 40%.
Manufacturability8
1.4935 +QT900's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability poor (24/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4935 +QT900
Is 1.4935 easy to machine?
Machine in the +A or freshly tempered condition with rigid setups, positive-rake carbide and generous coolant; work-hardening and poor chip breaking make feeds low and tool wear high.
Can 1.4935 be welded?
Weldable with matching 12CrMoWV filler using 300–400 °C preheat, controlled interpass and a mandatory 730–760 °C post-weld temper; avoid cooling below Ms before PWHT to prevent cracking.
Can 1.4935 be formed, bent or molded?
Hot form/forge at 1050–1150 °C with slow controlled cooling; essentially no useful cold formability in the quenched-and-tempered state.
What surface finishes work on 1.4935?
Passivate or fine-polish after grinding; for higher oxidation resistance above 600 °C use aluminizing or diffusion coatings — anodizing does not apply.
1.4935 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 | 0.17 – 0.23 | 0.2 |
| Si | ≤ 0.5 | 0.3 |
| Mn | 0.3 – 0.8 | 0.55 |
| P | ≤ 0.03 | — |
| S | ≤ 0.02 | — |
| Cr | 11 – 12.5 | 11.8 |
| Mo | 0.8 – 1.2 | 1 |
| Ni | 0.3 – 0.8 | 0.55 |
| V | 0.25 – 0.35 | 0.3 |
| Wtungsten addition distinguishes 1.4935 from 1.4922/1.4923 | 0.4 – 0.6 | 0.5 |
| Fe | balance | — |
1.4935 +QT900 — frequently asked
What is 1.4935 +QT900 used for?
1.4935 +QT900 is typically used for steam turbine blades, high-pressure turbine rotors, high-temperature bolting and power generation forgings. In short: tungsten-boosted 12Cr creep steel; 600 °C turbine service; forging and bolting grade.
What is the yield strength of 1.4935 +QT900?
1.4935 +QT900 has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 960 MPa (139 ksi) — stronger than 94% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 1.4935 +QT900 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Machine in the +A or freshly tempered condition with rigid setups, positive-rake carbide and generous coolant; work-hardening and poor chip breaking make feeds low and tool wear high.
Can 1.4935 +QT900 be welded?
Not readily — weldability is rated poor (24/100). Weldable with matching 12CrMoWV filler using 300–400 °C preheat, controlled interpass and a mandatory 730–760 °C post-weld temper; avoid cooling below Ms before PWHT to prevent cracking.
What surface finishes work on 1.4935 +QT900?
Passivate or fine-polish after grinding; for higher oxidation resistance above 600 °C use aluminizing or diffusion coatings — anodizing does not apply.
Can 1.4935 +QT900 be formed, bent or molded?
Hot form/forge at 1050–1150 °C with slow controlled cooling; essentially no useful cold formability in the quenched-and-tempered state.
What is the maximum service temperature of 1.4935 +QT900?
1.4935 +QT900 is rated for continuous use to about 560°C (1,040 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- DIN 17240 — Heat-resisting and creep-resisting steels for bolts and nuts — DIN (1976)
- EN 10302 — Creep resisting steels, nickel and cobalt alloys — CEN (2008)
- EN 10269 — Steels and nickel alloys for fasteners with specified elevated and/or low temperature properties — CEN (2013)
- EN 10088-1 — Stainless steels: list of stainless steels — CEN (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- 12% Cr creep-resisting turbine steel datasheets (X20/X22 CrMoV family) — European special steel producers (2020)
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.