Stainless Steel 415-QT900
Heat-treated state
AISI/SAE 415 · UNS S41500 · ASTM A487 Gr CA6NM
QT900 = quenched and tempered, Rm 900–1100 MPa
Highest-strength standard condition for shafts and highly loaded parts where toughness and NACE hardness limits are less critical.
Values for the QT900 condition
Other 415 tempers and conditions
415 is listed in 7 conditions; see the grade overview at 415.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Quenched and tempered, Rm 650–850 MPa | Maximum-toughness condition for thick turbine castings/forgings and sour or low-temperature service. | 520 | 730 | 22 | 19 HRC | — |
Solution annealed | Softest supply condition for heavy machining or cold work before final quench-and-temper. | 550 | 720 | 22 | 17 HRC | — |
ASTM A487 Gr. CA6NM Class A, normalized and tempered casting | Cast counterpart used for hydro turbine runners and pump casings; same metallurgy, slightly lower minimum strength and ductility than wrought. | 690 | 830 | 18 | 24 HRC | — |
QT780Default Quenched and double tempered, Rm 780–980 MPa | Standard commercial condition: best balance of 620 MPa yield, high CVN and weldability — pick this unless a spec says otherwise. | 700 | 850 | 18 | 25 HRC | — |
Cold drawn | Small-diameter bar with tight tolerance and bright finish; slightly higher yield, lower ductility than QT780. | 780 | 900 | 14 | 29 HRC | 2.9 % IACS |
As-welded deposit | Untempered fresh martensite in weld/HAZ — hard and low toughness; post-weld temper at 580–620 °C is normally required. | 800 | 1,000 | 12 | 38 HRC | 2.9 % IACS |
QT900This page Quenched and tempered, Rm 900–1100 MPa | Highest-strength standard condition for shafts and highly loaded parts where toughness and NACE hardness limits are less critical. | 870 | 980 | 15 | 31 HRC | — |
What is 415-QT900?
415-QT900 is 415 heat treated to QT900 — highest-strength standard condition for shafts and highly loaded parts where toughness and NACE hardness limits are less critical. 415-QT900 has a yield strength of 870 MPa (126 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi). 415-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). QT780 is the default condition FabDigit quotes; QT900 is available on request or by drawing note.
Advantages
- High strength — 870 MPa (126 ksi), better than 98% of stainless steel grades
- Conducts heat well — 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
Limitations
- Limited ductility — 15%, worse than 89% of stainless steel grades
- Limited formability — 20/100, worse than 86% of stainless steel grades
- Needs corrosion protection — 48/100, worse than 80% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
415-QT900 properties
Typical room-temperature values for 415-QT900; 14 are specific to this condition. Other listed values are 415 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
415-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
415-QT900 has a yield strength of 870 MPa (126 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
415-QT900 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
415-QT900 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of 415-QT900 takes about 53 MJ of energy and emits 4.5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 50%.
Manufacturability8
415-QT900's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability very good (72/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 415-QT900
Is 415 easy to machine?
Machines like a 28 HRC alloy steel — rigid setups, sharp positive-rake carbide, moderate speed and heavy feed to avoid work-hardened glaze; rough in the annealed condition when possible.
Can 415 be welded?
Best-welding martensitic stainless: use matching 410NiMo filler, preheat 100–150 °C on heavy sections, keep interpass <150 °C and post-weld temper 580–620 °C (never 450–550 °C).
Can 415 be formed, bent or molded?
Hot work at 1150–950 °C then air cool and temper; cold forming is limited to gentle bending with generous radii — final quench 950–1050 °C + double temper is preferred.
What surface finishes work on 415?
Passivate per ASTM A967 or electropolish after machining; takes a good mirror polish, and hard-chrome or thermal-spray overlays are common on turbine and shaft wear surfaces.
415 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 gives soft, tough lath martensite | ≤ 0.05 | 0.03 |
| Si | ≤ 0.6 | 0.3 |
| Mn | 0.5 – 1 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Cr | 11.5 – 14 | 12.75 |
| Ni | 3.5 – 5.5 | 4.5 |
| Mo | 0.5 – 1 | 0.7 |
| Nlimited in some product specs / EN 1.4313 | ≤ 0.03 | 0.02 |
| Fe | balance | — |
415-QT900 — frequently asked
What is 415-QT900 used for?
415-QT900 is typically used for hydro turbine runners, pump shafts, valve bodies and compressor parts. In short: best-welding martensitic stainless; wrought CA6NM equivalent; tough at 700 MPa yield.
What is the yield strength of 415-QT900?
415-QT900 has a typical yield strength of 870 MPa (126 ksi) and a tensile strength of 980 MPa (142 ksi) — stronger than 98% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 415-QT900 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Machines like a 28 HRC alloy steel — rigid setups, sharp positive-rake carbide, moderate speed and heavy feed to avoid work-hardened glaze; rough in the annealed condition when possible.
Can 415-QT900 be welded?
Yes — weldability is rated very good (72/100). Best-welding martensitic stainless: use matching 410NiMo filler, preheat 100–150 °C on heavy sections, keep interpass <150 °C and post-weld temper 580–620 °C (never 450–550 °C).
What surface finishes work on 415-QT900?
Passivate per ASTM A967 or electropolish after machining; takes a good mirror polish, and hard-chrome or thermal-spray overlays are common on turbine and shaft wear surfaces.
Can 415-QT900 be formed, bent or molded?
Hot work at 1150–950 °C then air cool and temper; cold forming is limited to gentle bending with generous radii — final quench 950–1050 °C + double temper is preferred.
What is the maximum service temperature of 415-QT900?
415-QT900 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.
What is the difference between 415-QT780 and 415-QT650?
QT780 is the default condition — standard commercial condition: best balance of 620 MPa yield, high CVN and weldability — pick this unless a spec says otherwise. QT650: maximum-toughness condition for thick turbine castings/forgings and sour or low-temperature service. Yield strength is 700 MPa in QT780 versus 520 MPa in QT650.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip (UNS S41500) — ASTM International (2023)
- ASTM A182/A182M — Forged or Rolled Alloy and Stainless Steel Pipe Flanges and Fittings (Grade F6NM) — ASTM International (2022)
- ASTM A487/A487M — Steel Castings Suitable for Pressure Service (Grade CA6NM) — ASTM International (2020)
- EN 10088-3 — Stainless steels, Part 3: Semi-finished products, bars, rods (X3CrNiMo13-4, 1.4313) — CEN (2014)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
- Soft martensitic stainless 1.4313 / S41500 datasheet — Böhler / Sandvik / Outokumpu (2022)
- GB/T 1220 ZG06Cr13Ni4Mo (2007)
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.