Stainless Steel 1.4423 +QT900
Heat-treated state · default condition
EN 1.4423
+QT900 = quenched and tempered to Rm 900–1050 MPa
Standard stocked condition for pump shafts and impellers needing high strength with good corrosion resistance.
Values for the +QT900 condition
Other 1.4423 tempers and conditions
1.4423 is listed in 7 conditions; see the grade overview at 1.4423.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Quenched and tempered to Rm 700–850 MPa | High-tempering condition for maximum toughness and sour-service hardness limits (<22 HRC targets where required). | 560 | 760 | 20 | 21 HRC | — |
Annealed | Pick for heavy machining, deep drilling or cold straightening before a final quench-and-temper cycle. | 600 | 800 | 20 | 25 HRC | 2.3 % IACS |
Quenched and tempered to Rm 800–950 MPa | Balanced strength/toughness condition for valve stems and medium-duty pump shafts. | 680 | 870 | 18 | 27 HRC | 2.3 % IACS |
As-welded deposit | Reference condition for fabrication checks; a post-weld temper is normally required to restore toughness and sour-service hardness. | 700 | 900 | 13 | 35 HRC | 2.3 % IACS |
+QT900DefaultThis page Quenched and tempered to Rm 900–1050 MPa | Standard stocked condition for pump shafts and impellers needing high strength with good corrosion resistance. | 780 | 950 | 16 | 31 HRC | — |
Cold drawn | Choose for close-tolerance shaft blanks where h9/h7 dimensional accuracy and surface finish are needed without further turning. | 820 | 980 | 14 | 32 HRC | 2.3 % IACS |
Quenched and low-temperature tempered / Cu-aged, Rm ≥ 1000 MPa | Highest-strength condition, using copper precipitation on low tempering; choose for highly loaded shafts in non-sour service. | 900 | 1,080 | 14 | 36 HRC | — |
What is 1.4423 +QT900?
1.4423 +QT900 is 1.4423 heat treated to +QT900 — standard stocked condition for pump shafts and impellers needing high strength with good corrosion resistance. 1.4423 +QT900 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 95% of stainless steel grades. Elongation at break is 16% and the elastic modulus is 200 GPa (29 Msi). 1.4423 +QT900 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Advantages
- High strength — 780 MPa (113 ksi), better than 95% of stainless steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
- Limited ductility — 16%, worse than 88% of stainless steel grades
1.4423 +QT900 properties
Typical room-temperature values for 1.4423 +QT900; 10 are specific to this condition. Other listed values are 1.4423 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4423 +QT900 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
1.4423 +QT900 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 95% of stainless steel grades. Elongation at break is 16% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1.4423 +QT900 is rated for continuous service to 300°C (572 °F). It conducts heat at 16 W/m·K (9.24 BTU/hr·ft·°F), better than 58% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
1.4423 +QT900 conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), worse than 62% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4423 +QT900 takes about 55 MJ of energy and emits 4.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
1.4423 +QT900's machinability is fair (38/100, better than 63% of stainless steel grades); weldability very good (72/100); formability poor (32/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4423 +QT900
Is 1.4423 easy to machine?
Machines like a 30 HRC low-carbon martensitic stainless: gummy and work-hardening, so use rigid setups, sharp coated carbide, positive rake, 60–110 m/min turning speeds and generous high-pressure coolant.
Can 1.4423 be welded?
Very good for a martensitic grade thanks to <0.02 % C — TIG/MIG with matching or 22-9-3/625-type filler, low heat input, preheat 100–150 °C on heavy sections and a post-weld temper below the base-metal tempering temperature.
Can 1.4423 be formed, bent or molded?
Hot forge 1150–900 °C then air-cool and re-austenitize/temper; cold forming is limited to mild straightening and thread rolling in the softened condition.
What surface finishes work on 1.4423?
Polishes to a fine finish and passivates well in nitric or citric acid; avoid chloride-bearing pickles at high temperature, and keep final hardness ≤ 32 HRC where sour-service or plating-related hydrogen embrittlement is a concern.
1.4423 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 |
|---|---|---|
| Cultra-low carbon, ensures soft/tough martensite | ≤ 0.02 | 0.01 |
| Si | ≤ 0.7 | 0.35 |
| Mn | ≤ 2 | 0.7 |
| P | ≤ 0.03 | — |
| Slow S for toughness and pitting resistance | ≤ 0.01 | — |
| Cr | 11 – 12.5 | 12 |
| Ni | 6 – 7.5 | 7 |
| Mo | 2.5 – 3.5 | 3 |
| Cuapproximate; provides age-hardening response | 1 – 2 | 1.5 |
| N | ≤ 0.02 | — |
| Fe | balance | — |
1.4423 +QT900 — frequently asked
What is 1.4423 +QT900 used for?
1.4423 +QT900 is typically used for chemical process pumps, valve trim and marine pump impellers. In short: most corrosion-resistant soft martensitic; upgrade from 1.4422; carbon below 0.02 %.
What is the yield strength of 1.4423 +QT900?
1.4423 +QT900 has a typical yield strength of 780 MPa (113 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 95% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 1.4423 +QT900 easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Machines like a 30 HRC low-carbon martensitic stainless: gummy and work-hardening, so use rigid setups, sharp coated carbide, positive rake, 60–110 m/min turning speeds and generous high-pressure coolant.
Can 1.4423 +QT900 be welded?
Yes — weldability is rated very good (72/100). Very good for a martensitic grade thanks to <0.02 % C — TIG/MIG with matching or 22-9-3/625-type filler, low heat input, preheat 100–150 °C on heavy sections and a post-weld temper below the base-metal tempering temperature.
What surface finishes work on 1.4423 +QT900?
Polishes to a fine finish and passivates well in nitric or citric acid; avoid chloride-bearing pickles at high temperature, and keep final hardness ≤ 32 HRC where sour-service or plating-related hydrogen embrittlement is a concern.
Can 1.4423 +QT900 be formed, bent or molded?
Hot forge 1150–900 °C then air-cool and re-austenitize/temper; cold forming is limited to mild straightening and thread rolling in the softened condition.
What is the maximum service temperature of 1.4423 +QT900?
1.4423 +QT900 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4423 +QT900 and 1.4423-AW?
+QT900 is the default condition — standard stocked condition for pump shafts and impellers needing high strength with good corrosion resistance. AW: reference condition for fabrication checks; a post-weld temper is normally required to restore toughness and sour-service hardness. Yield strength is 780 MPa in +QT900 versus 700 MPa in AW.
Sources
- EN 10088-3 Stainless steels — Technical delivery conditions for semi-finished products, bars, rods, wire — CEN (2014)
- EN 10088-1 Stainless steels — List of stainless steels (physical property data) — CEN (2014)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- ANSI/NACE MR0175 / ISO 15156-3 — Materials for use in H2S-containing environments — NACE/ISO (2015)
- Supermartensitic stainless pump-shaft bar datasheets (12Cr-Ni-Mo-Cu class) — European long-product mills (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.