Stainless Steel 1.4421 +QT1
Heat-treated state · default condition
EN 1.4421
+QT1 = austenitized, air/oil quenched and high-temperature tempered
Standard supply condition for hydro turbine, pump and valve castings where toughness, weld repairability and impact energy matter more than peak strength.
Values for the +QT1 condition
Other 1.4421 tempers and conditions
1.4421 is listed in 2 conditions; see the grade overview at 1.4421.
- +QT1
- +QT2
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+QT1DefaultThis page Austenitized, air/oil quenched and high-temperature tempered | Standard supply condition for hydro turbine, pump and valve castings where toughness, weld repairability and impact energy matter more than peak strength. | 620 | 850 | 18 | 26 HRC | 25 W/m·K |
Austenitized, quenched and tempered at lower temperature | Choose when higher proof strength is required for highly loaded runners, impellers or hydraulic bodies and the lower impact energy / reduced sour-service margin is acceptable. | 880 | 1,050 | 13 | 34 HRC | 25 W/m·K |
What is 1.4421 +QT1?
1.4421 +QT1 is 1.4421 heat treated to +QT1 — standard supply condition for hydro turbine, pump and valve castings where toughness, weld repairability and impact energy matter more than peak strength. 1.4421 +QT1 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 18% and the elastic modulus is 200 GPa (29 Msi). 1.4421 +QT1 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
- Conducts heat well — 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades
- High strength — 620 MPa (89.9 ksi), better than 88% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
Limitations
- Limited formability — 10/100, worse than 95% of stainless steel grades
- Limited ductility — 18%, worse than 83% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
1.4421 +QT1 properties
Typical room-temperature values for 1.4421 +QT1; 21 are specific to this condition. Other listed values are 1.4421 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4421 +QT1 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
1.4421 +QT1 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 18% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1.4421 +QT1 is rated for continuous service to 400°C (752 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
1.4421 +QT1 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (57/100), worse than 66% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4421 +QT1 takes about 50 MJ of energy and emits 4.5 kg of CO₂ — less than 80% of stainless steel grades. Typical recycled content is 70%.
Manufacturability7
1.4421 +QT1's machinability is fair (42/100, better than 79% of stainless steel grades); weldability very good (72/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4421 +QT1
Is 1.4421 easy to machine?
Machine after tempering with rigid setups, sharp carbide tooling, moderate speed and heavy positive feed to avoid work hardening; the tough martensite makes chips stringy and drives insert notch wear.
Can 1.4421 be welded?
Very good for a martensitic grade: use matching 16-5 or 13-4 low-carbon consumables, preheat/interpass 100–160 °C, avoid excessive heat input, then post-weld temper below the original tempering temperature.
Can 1.4421 be formed, bent or molded?
Supplied as a casting — no cold forming; ensure directional solidification with adequate risering and hot isostatic pressing or weld repair for critical pressure/cavitation surfaces.
What surface finishes work on 1.4421?
Passivate after machining and grinding to restore the chromium oxide film; takes a fine ground/polished finish, and can be hard-chrome or thermal-spray coated on wear/cavitation zones.
1.4421 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 for soft martensite and weldability | ≤ 0.06 | 0.04 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 1 | 0.7 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Cr | 15 – 17 | 16 |
| Ni | 3.5 – 5 | 4.3 |
| Moresidual only — grade is nominally Mo-free | ≤ 0.7 | 0.2 |
| N | ≤ 0.05 | 0.03 |
| Fe | balance | — |
1.4421 +QT1 — frequently asked
What is 1.4421 +QT1 used for?
1.4421 +QT1 is typically used for hydraulic turbine components, pump casings and impellers and general corrosion-resistant castings. In short: weldable martensitic casting; molybdenum-free 16Cr-4Ni; better corrosion than 13Cr-4Ni.
What is the yield strength of 1.4421 +QT1?
1.4421 +QT1 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 88% of stainless steel grades. Strength varies by condition: see the 2 listed tempers.
Is 1.4421 +QT1 easy to machine?
Not especially — machinability is rated fair (42/100, better than 79% of stainless steel grades). Machine after tempering with rigid setups, sharp carbide tooling, moderate speed and heavy positive feed to avoid work hardening; the tough martensite makes chips stringy and drives insert notch wear.
Can 1.4421 +QT1 be welded?
Yes — weldability is rated very good (72/100). Very good for a martensitic grade: use matching 16-5 or 13-4 low-carbon consumables, preheat/interpass 100–160 °C, avoid excessive heat input, then post-weld temper below the original tempering temperature.
What surface finishes work on 1.4421 +QT1?
Passivate after machining and grinding to restore the chromium oxide film; takes a fine ground/polished finish, and can be hard-chrome or thermal-spray coated on wear/cavitation zones.
Can 1.4421 +QT1 be formed, bent or molded?
Supplied as a casting — no cold forming; ensure directional solidification with adequate risering and hot isostatic pressing or weld repair for critical pressure/cavitation surfaces.
What is the maximum service temperature of 1.4421 +QT1?
1.4421 +QT1 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.
Sources
- EN 10283 — Corrosion resistant steel castings — CEN (2010)
- EN 10213 — Steel castings for pressure purposes — CEN (2016)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Steel Castings Handbook (soft martensitic CA6NM-type alloys) — Steel Founders' Society of America (1995)
- Stainless steel foundry datasheets for GX4CrNi13-4 / GX4CrNi16-4 castings — various European foundries (2022)
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.