Stainless Steel 1.4415 +QT750
Heat-treated state
EN 1.4415 · UNS S41426
+QT750 = quenched and tempered, Rm 750–950 MPa class
Pick when maximum toughness, weld repairability and sour-service margin matter more than strength (hydro turbine runners, large valve bodies).
Values for the +QT750 condition
Other 1.4415 tempers and conditions
1.4415 is listed in 5 conditions; see the grade overview at 1.4415.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for rough machining of large forgings before final quench and temper; lowest hardness available for this grade. | 560 | 780 | 20 | 24 HRC | — |
+QT750This page Quenched and tempered, Rm 750–950 MPa class | Pick when maximum toughness, weld repairability and sour-service margin matter more than strength (hydro turbine runners, large valve bodies). | 620 | 820 | 18 | 25 HRC | — |
+QT850Default Quenched and tempered, Rm 850–1000 MPa class | Standard stocked forging condition — highest strength of the two EN classes while retaining good CVN toughness; use for pump/compressor shafts and highly loaded valve and turbine parts. | 720 | 900 | 17 | 29 HRC | — |
Q&T to NACE MR0175 / ISO 15156-3 sour-service limits | Pick for H2S-containing oil & gas hardware — double-tempered to a capped hardness with documented H2S partial pressure, chloride and temperature envelope. | 720 | 900 | 17 | 30 HRC | 2.7 % IACS |
Quenched and tempered, ~900–1100 MPa high-strength class | Special-order high-strength condition for shafts and OCTG-type components where hardness above 32 HRC is acceptable (not for sour service). | 800 | 980 | 15 | 33 HRC | — |
What is 1.4415 +QT750?
1.4415 +QT750 is 1.4415 heat treated to +QT750 — pick when maximum toughness, weld repairability and sour-service margin matter more than strength (hydro turbine runners, large valve bodies). 1.4415 +QT750 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 18% and the elastic modulus is 215 GPa (31.2 Msi). 1.4415 +QT750 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). +QT850 is the default condition FabDigit quotes; +QT750 is available on request or by drawing note.
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
- Low embodied carbon — 3.6 kg CO₂/kg, better than 83% of stainless steel grades
- High electrical conductivity — 2.7 % IACS, better than 78% of stainless steel grades
Limitations
- Limited ductility — 18%, worse than 83% of stainless steel grades
- Limited formability — 25/100, worse than 78% of stainless steel grades
- Needs corrosion protection — 52/100, worse than 76% of stainless steel grades
1.4415 +QT750 properties
Typical room-temperature values for 1.4415 +QT750; 18 are specific to this condition. Other listed values are 1.4415 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4415 +QT750 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
1.4415 +QT750 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 18% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
1.4415 +QT750 is rated for continuous service to 450°C (842 °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
1.4415 +QT750 conducts electricity at 2.7 % IACS, better than 78% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (52/100), worse than 76% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4415 +QT750 takes about 53 MJ of energy and emits 3.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 50%.
Manufacturability8
1.4415 +QT750's machinability is fair (40/100, better than 72% of stainless steel grades); weldability very good (75/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4415 +QT750
Is 1.4415 easy to machine?
Machine like Q&T 13Cr-4Ni: rigid setups, sharp positive-rake carbide (or coated CVD grades), moderate speed with heavy constant feed to avoid work-hardened glazing; flood coolant and avoid dwelling.
Can 1.4415 be welded?
Very good for a martensitic grade thanks to <0.03 % C — GTAW/GMAW/SMAW with matching 13/4 or 13/5 filler, preheat/interpass typically 100–160 °C, then post-weld temper (single or double) below Ac1 to restore toughness.
Can 1.4415 be formed, bent or molded?
Hot forge/roll around 1100–1150 °C with controlled finishing temperature; cold forming is limited in the Q&T condition, so bending and straightening should be done warm or in the annealed state.
What surface finishes work on 1.4415?
Passivate per ASTM A967 or electropolish after machining; takes a good mechanical polish, and can be nitrided or hard-chrome plated for wear surfaces (no anodizing — ferrous alloy).
1.4415 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 (X2) | ≤ 0.03 | 0.02 |
| Si | ≤ 0.7 | 0.4 |
| Mn | ≤ 1.5 | 0.7 |
| P | ≤ 0.03 | — |
| S≤0.005 typical for sour service (S41426) | ≤ 0.01 | — |
| Cr | 12 – 14 | 13 |
| Ni | 4.5 – 6 | 5.2 |
| Mo | 1.5 – 2.5 | 2 |
| VV addition distinguishes this grade from 1.4313 | 0.1 – 0.5 | 0.3 |
| N | ≤ 0.08 | 0.03 |
| Curesidual limit per sour-service practice | ≤ 0.3 | — |
| Fe | balance | — |
1.4415 +QT750 — frequently asked
What is 1.4415 +QT750 used for?
1.4415 +QT750 is typically used for high-head hydro turbine runners, offshore pump shafts and marine valve components. In short: stronger than 1.4313; NACE-capable soft martensitic; weldable at 29 HRC.
What is the yield strength of 1.4415 +QT750?
1.4415 +QT750 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 88% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 1.4415 +QT750 easy to machine?
Not especially — machinability is rated fair (40/100, better than 72% of stainless steel grades). Machine like Q&T 13Cr-4Ni: rigid setups, sharp positive-rake carbide (or coated CVD grades), moderate speed with heavy constant feed to avoid work-hardened glazing; flood coolant and avoid dwelling.
Can 1.4415 +QT750 be welded?
Yes — weldability is rated very good (75/100). Very good for a martensitic grade thanks to <0.03 % C — GTAW/GMAW/SMAW with matching 13/4 or 13/5 filler, preheat/interpass typically 100–160 °C, then post-weld temper (single or double) below Ac1 to restore toughness.
What surface finishes work on 1.4415 +QT750?
Passivate per ASTM A967 or electropolish after machining; takes a good mechanical polish, and can be nitrided or hard-chrome plated for wear surfaces (no anodizing — ferrous alloy).
Can 1.4415 +QT750 be formed, bent or molded?
Hot forge/roll around 1100–1150 °C with controlled finishing temperature; cold forming is limited in the Q&T condition, so bending and straightening should be done warm or in the annealed state.
What is the maximum service temperature of 1.4415 +QT750?
1.4415 +QT750 is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4415 +QT850 and 1.4415 QT-NACE?
+QT850 is the default condition — standard stocked forging condition — highest strength of the two EN classes while retaining good CVN toughness; use for pump/compressor shafts and highly loaded valve and turbine parts. QT-NACE: pick for H2S-containing oil & gas hardware — double-tempered to a capped hardness with documented H2S partial pressure, chloride and temperature envelope. Yield strength is 720 MPa in +QT850 versus 720 MPa in QT-NACE.
Sources
- EN 10088-3 Stainless steels — Technical delivery conditions for semi-finished products, bars, rods, wire, sections — CEN (2014)
- EN 10250-4 Open die steel forgings for general engineering purposes — Stainless steels — CEN (2000)
- ISO 15156-3 / NACE MR0175 — Cracking-resistant CRAs for H2S-containing environments (UNS S41426) — ISO/NACE (2020)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Soft martensitic stainless steel forging grades (13Cr-4Ni / 13Cr-5Ni-2Mo) datasheets — European forging/long-product producers (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.