Stainless Steel 1.4029 +QT850
Heat-treated state
EN 1.4029
+QT850 = quenched and tempered, Rm 850–1000 MPa
Standard delivered Q&T class of EN 10088-3 for this grade — highest tempered strength still supplied as bar.
Values for the +QT850 condition
Other 1.4029 tempers and conditions
1.4029 is listed in 6 conditions; see the grade overview at 1.4029.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ADefault Annealed | Standard stocked bar condition: softest state for heavy automatic-lathe turning before hardening. | 450 | 740 | 15 | 215 HB | — |
Quenched and tempered, Rm 750–900 MPa | Lowest-strength Q&T class: pick when toughness and dimensional stability matter more than hardness. | 600 | 810 | 12 | 23 HRC | — |
Cold drawn | Choose for close-tolerance bright bar feeding Swiss/CNC automatics where no further hardening is planned. | 620 | 830 | 10 | 24 HRC | 3 % IACS |
Quenched and tempered, Rm 800–950 MPa | Mid Q&T class for shafts, spindles and valve stems needing balanced strength and machinability. | 640 | 870 | 11 | 26 HRC | — |
+QT850This page Quenched and tempered, Rm 850–1000 MPa | Standard delivered Q&T class of EN 10088-3 for this grade — highest tempered strength still supplied as bar. | 700 | 920 | 10 | 28 HRC | — |
Hardened & low-temperature tempered | Part-level treatment (1000–1050 °C oil/air quench + 150–250 °C temper) for wear faces, cutlery bolsters and valve seats. | 1,350 | 1,600 | 3 | 50 HRC | — |
What is 1.4029 +QT850?
1.4029 +QT850 is 1.4029 heat treated to +QT850 — standard delivered Q&T class of EN 10088-3 for this grade — highest tempered strength still supplied as bar. 1.4029 +QT850 has a yield strength of 700 MPa (102 ksi) and a tensile strength of 920 MPa (133 ksi) — stronger than 92% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 215 GPa (31.2 Msi). 1.4029 +QT850 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). +A is the default condition FabDigit quotes; +QT850 is available on request or by drawing note.
Advantages
- Conducts heat well — 30 W/m·K (17.3 BTU/hr·ft·°F), better than 99% of stainless steel grades
- High electrical conductivity — 3.1 % IACS, better than 99% of stainless steel grades
- High strength — 700 MPa (102 ksi), better than 92% of stainless steel grades
- Low embodied carbon — 3.4 kg CO₂/kg, better than 91% of stainless steel grades
- Easy to machine — 48/100, better than 88% of stainless steel grades
Limitations
- Needs corrosion protection — 28/100, worse than 100% of stainless steel grades
- Hard to polish — 35/100, worse than 100% of stainless steel grades
- Difficult to weld — 12/100, worse than 99% of stainless steel grades
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Limited ductility — 10%, worse than 98% of stainless steel grades
1.4029 +QT850 properties
Typical room-temperature values for 1.4029 +QT850; 18 are specific to this condition. Other listed values are 1.4029 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4029 +QT850 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
1.4029 +QT850 has a yield strength of 700 MPa (102 ksi) and a tensile strength of 920 MPa (133 ksi) — stronger than 92% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
1.4029 +QT850 is rated for continuous service to 400°C (752 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), better than 99% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
1.4029 +QT850 conducts electricity at 3.1 % IACS, better than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is poor (28/100), worse than 100% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4029 +QT850 takes about 40 MJ of energy and emits 3.4 kg of CO₂ — less than 97% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
1.4029 +QT850's machinability is fair (48/100, better than 88% of stainless steel grades); weldability not recommended (12/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4029 +QT850
Is 1.4029 easy to machine?
Excellent for a stainless: carbide or HSS, sharp positive geometry, 90–140 m/min in +A; sulfides give short chips and long tool life, but tool pressure rises sharply above 28 HRC.
Can 1.4029 be welded?
Not recommended — high carbon plus 0.2 % S causes hot cracking and brittle martensite; if unavoidable, preheat 250–300 °C, 309/410NiMo filler, immediate 700–750 °C temper.
Can 1.4029 be formed, bent or molded?
Essentially a machining bar grade; cold bending, heading or deep drawing will crack — hot form 1100–850 °C then slow cool and re-anneal.
What surface finishes work on 1.4029?
Passivate in nitric acid after machining (sulfide pits bleed rust otherwise), hard chrome or nitriding for wear; high-gloss polishing is poor because MnS stringers pull out.
1.4029 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 |
|---|---|---|
| CEN 10088-3 | 0.25 – 0.32 | 0.29 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1.5 | 0.8 |
| P | ≤ 0.04 | 0.03 |
| Sdeliberate sulfur addition for free machining | 0.15 – 0.25 | 0.2 |
| Cr | 12 – 13.5 | 12.8 |
| Mooptional residual/addition | ≤ 0.6 | 0.1 |
| Niresidual, mill practice | ≤ 0.5 | 0.2 |
| Fe | balance | — |
1.4029 +QT850 — frequently asked
What is 1.4029 +QT850 used for?
1.4029 +QT850 is typically used for valve stems, screws and turned stainless components. In short: best-machining martensitic stainless; free-machining version of 1.4028; lowest corrosion rating in family.
What is the yield strength of 1.4029 +QT850?
1.4029 +QT850 has a typical yield strength of 700 MPa (102 ksi) and a tensile strength of 920 MPa (133 ksi) — stronger than 92% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is 1.4029 +QT850 easy to machine?
Reasonably — machinability is rated fair (48/100, better than 88% of stainless steel grades). Excellent for a stainless: carbide or HSS, sharp positive geometry, 90–140 m/min in +A; sulfides give short chips and long tool life, but tool pressure rises sharply above 28 HRC.
Can 1.4029 +QT850 be welded?
Not readily — weldability is rated not recommended (12/100). Not recommended — high carbon plus 0.2 % S causes hot cracking and brittle martensite; if unavoidable, preheat 250–300 °C, 309/410NiMo filler, immediate 700–750 °C temper.
What surface finishes work on 1.4029 +QT850?
Passivate in nitric acid after machining (sulfide pits bleed rust otherwise), hard chrome or nitriding for wear; high-gloss polishing is poor because MnS stringers pull out.
Can 1.4029 +QT850 be formed, bent or molded?
Essentially a machining bar grade; cold bending, heading or deep drawing will crack — hot form 1100–850 °C then slow cool and re-anneal.
What is the maximum service temperature of 1.4029 +QT850?
1.4029 +QT850 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 10088-3: Stainless steels — Technical delivery conditions for semi-finished products, bars, rods, sections — CEN (2014)
- EN 10088-1: Stainless steels — List of stainless steels (physical properties) — CEN (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- GB/T 1220 (Y3Cr13 free-machining martensitic bar) — SAC (2007)
- Free-machining martensitic bar (X29CrS13 / 420F) datasheets — Sandvik / Böhler / Outokumpu (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.