Stainless Steel 1.4418 +QT900
Heat-treated state · default condition
EN 1.4418
+QT900 = quenched and tempered, Rm 900–1100 MPa
Most commonly stocked bar condition: highest strength level of the grade while keeping useful impact toughness.
Values for the +QT900 condition
Other 1.4418 tempers and conditions
1.4418 is listed in 5 conditions; see the grade overview at 1.4418.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Delivery condition for further machining, forming or subsequent hardening; lowest hardness available for this grade. | 600 | 800 | 20 | 25 HRC | — |
+QT | Double-tempered low-hardness condition specified for H2S-containing (sour) oil & gas and offshore pump components. | 600 | 800 | 21 | 22 HRC | — |
Quenched and tempered, Rm 760–960 MPa | Highest-toughness Q&T level; choose for heavy sections, welded fabrications and low-temperature impact requirements. | 620 | 850 | 20 | 24 HRC | — |
Quenched and tempered, Rm 840–980 MPa | Balanced strength/toughness condition widely used for pump and valve shafts in seawater service. | 700 | 900 | 18 | 28 HRC | — |
+QT900DefaultThis page Quenched and tempered, Rm 900–1100 MPa | Most commonly stocked bar condition: highest strength level of the grade while keeping useful impact toughness. | 780 | 980 | 17 | 31 HRC | — |
What is 1.4418 +QT900?
1.4418 +QT900 is 1.4418 heat treated to +QT900 — most commonly stocked bar condition: highest strength level of the grade while keeping useful impact toughness. 1.4418 +QT900 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 95% of stainless steel grades. Elongation at break is 17% and the elastic modulus is 200 GPa (29 Msi). 1.4418 +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 — 17%, worse than 86% of stainless steel grades
- Limited formability — 22/100, worse than 82% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
1.4418 +QT900 properties
Typical room-temperature values for 1.4418 +QT900; 18 are specific to this condition. Other listed values are 1.4418 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4418 +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
1.4418 +QT900 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 95% of stainless steel grades. Elongation at break is 17% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1.4418 +QT900 is rated for continuous service to 300°C (572 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
1.4418 +QT900 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4418 +QT900 takes about 55 MJ of energy and emits 5.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
1.4418 +QT900's machinability is fair (35/100, better than 51% of stainless steel grades); weldability good (68/100); formability poor (22/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4418 +QT900
Is 1.4418 easy to machine?
Machines like a 30 HRC alloy steel: rigid setups, sharp coated carbide, moderate speed with heavy positive feed to cut under the work-hardened skin, ample coolant.
Can 1.4418 be welded?
Readily weldable by GTAW/GMAW/SMAW without preheat in thin sections (preheat 100–150 °C for heavy sections); use matching 16-5-1 or austenitic 309L/316L filler and post-weld temper at ~580–620 °C to restore HAZ toughness.
Can 1.4418 be formed, bent or molded?
Hot forge/roll at 1100–1200 °C and air cool; cold forming is limited by the hard martensitic matrix — bend only in the annealed condition with generous radii.
What surface finishes work on 1.4418?
Passivate (ASTM A967 nitric/citric) or electropolish after machining; not anodizable, takes hard chrome, nitriding or PVD for wear surfaces and polishes to a good mirror finish.
1.4418 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 |
|---|---|---|
| Clow carbon soft martensite | ≤ 0.06 | 0.04 |
| Si | ≤ 0.7 | 0.4 |
| Mn | ≤ 1.5 | 0.8 |
| P | ≤ 0.04 | — |
| S | ≤ 0.02 | — |
| Cr | 15 – 17 | 16 |
| Ni | 4 – 6 | 5 |
| Mo | 0.8 – 1.5 | 1 |
| NEN 10088-3 requires N ≥ 0.020 | 0.02 – 0.07 | 0.04 |
| Fe | balance | — |
1.4418 +QT900 — frequently asked
What is 1.4418 +QT900 used for?
1.4418 +QT900 is typically used for seawater pump shafts, valve stems and hydraulic components. In short: most corrosion-resistant soft martensitic; higher strength than 1.4313; weldable 31 HRC stainless.
What is the yield strength of 1.4418 +QT900?
1.4418 +QT900 has a typical yield strength of 780 MPa (113 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 95% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 1.4418 +QT900 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of stainless steel grades). Machines like a 30 HRC alloy steel: rigid setups, sharp coated carbide, moderate speed with heavy positive feed to cut under the work-hardened skin, ample coolant.
Can 1.4418 +QT900 be welded?
Yes — weldability is rated good (68/100). Readily weldable by GTAW/GMAW/SMAW without preheat in thin sections (preheat 100–150 °C for heavy sections); use matching 16-5-1 or austenitic 309L/316L filler and post-weld temper at ~580–620 °C to restore HAZ toughness.
What surface finishes work on 1.4418 +QT900?
Passivate (ASTM A967 nitric/citric) or electropolish after machining; not anodizable, takes hard chrome, nitriding or PVD for wear surfaces and polishes to a good mirror finish.
Can 1.4418 +QT900 be formed, bent or molded?
Hot forge/roll at 1100–1200 °C and air cool; cold forming is limited by the hard martensitic matrix — bend only in the annealed condition with generous radii.
What is the maximum service temperature of 1.4418 +QT900?
1.4418 +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.
Sources
- EN 10088-3 Stainless steels – Semi-finished products, bars, rods, sections — CEN (2014)
- EN 10088-1 Stainless steels – List of stainless steels — CEN (2014)
- ASTM A182 / UNS S41500 (comparable soft martensitic grade) — ASTM (2022)
- 1.4418 / X4CrNiMo16-5-1 bar datasheet — Deutsche Edelstahlwerke / Zapp (2020)
- ASM Handbook Vol.1: Properties and Selection – Irons, Steels — ASM International (1990)
- NACE MR0175 / ISO 15156-3 (hardness limits for martensitic stainless steels) — NACE/ISO (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.