Stainless Steel 1.4125-QT500
Heat-treated state
EN 1.4125
QT500 = hardened, tempered 450–550 °C
Used only when elevated-temperature stability is needed; corrosion resistance and toughness drop markedly.
Values for the QT500 condition
Other 1.4125 tempers and conditions
1.4125 is listed in 8 conditions; see the grade overview at 1.4125.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ADefault Annealed | Standard stock condition for machining before hardening; softest and most workable state. | 450 | 760 | 14 | 250 HB | — |
Annealed and cold drawn bar | Cold-drawn annealed bar for tight tolerance and better surface before hardening; slightly higher strength, lower ductility. | 650 | 880 | 10 | 29 HRC | — |
QT500This page Hardened, tempered 450–550 °C | Used only when elevated-temperature stability is needed; corrosion resistance and toughness drop markedly. | 1,650 | 1,800 | 3 | 54 HRC | 2.7 % IACS |
Hardened, tempered 250–350 °C | Slightly lower hardness with better stress relief for larger tooling and valve components. | 1,790 | 1,900 | 3 | 56 HRC | — |
Quenched and tempered | Generic delivered hardened condition per EN 10088-3 for wear parts; specify tempering temperature for the exact hardness. | 1,900 | 1,970 | 2 | 58 HRC | — |
As-quenched | Intermediate state only — extremely brittle and stressed; always temper before service. | 1,900 | 2,000 | 0.5 | 63 HRC | — |
Hardened, tempered 150–200 °C | Maximum hardness with best corrosion resistance — standard for bearing races/balls and premium knife blades. | 1,930 | 2,030 | 2 | 59 HRC | — |
Hardened, deep-frozen (−80 °C) and tempered | Sub-zero treatment converts retained austenite for maximum hardness and dimensional stability in bearings and gauges. | — | 2,100 | 1 | 61 HRC | — |
What is 1.4125-QT500?
1.4125-QT500 is 1.4125 heat treated to QT500 — used only when elevated-temperature stability is needed; corrosion resistance and toughness drop markedly. 1.4125-QT500 has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi). 1.4125-QT500 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,370°C (2,498 °F). +A is the default condition FabDigit quotes; QT500 is available on request or by drawing note.
Advantages
- High strength — 1,650 MPa (239 ksi), better than 100% of stainless steel grades
- Conducts heat well — 23 W/m·K (13.3 BTU/hr·ft·°F), better than 78% of stainless steel grades
- High electrical conductivity — 2.7 % IACS, better than 78% of stainless steel grades
Limitations
- Limited ductility — 3%, worse than 100% of stainless steel grades
- Needs corrosion protection — 28/100, worse than 100% of stainless steel grades
- Difficult to machine — 10/100, worse than 100% of stainless steel grades
- Difficult to weld — 5/100, worse than 100% of stainless steel grades
- Limited formability — 5/100, worse than 99% of stainless steel grades
1.4125-QT500 properties
Typical room-temperature values for 1.4125-QT500; 22 are specific to this condition. Other listed values are 1.4125 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4125-QT500 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical14
1.4125-QT500 has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1.4125-QT500 is rated for continuous service to 420°C (788 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), better than 78% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
1.4125-QT500 conducts electricity at 2.7 % IACS, better than 78% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is poor (28/100), worse than 100% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4125-QT500 takes about 55 MJ of energy and emits 5.2 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
1.4125-QT500's machinability is not recommended (10/100, worse than 100% of stainless steel grades); weldability not recommended (5/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4125-QT500
Is 1.4125 easy to machine?
Machine only in the annealed condition with sharp carbide tooling, low speed and rigid setups; hardened parts require grinding or EDM.
Can 1.4125 be welded?
Essentially not recommended — high carbon causes cracking; if unavoidable preheat 250–350 °C, use matching or austenitic filler and immediately anneal/temper.
Can 1.4125 be formed, bent or molded?
Cold forming is very limited (annealed sheet only, generous radii); hot work 1100→850 °C followed by slow cool and spheroidize anneal.
What surface finishes work on 1.4125?
Takes a high mirror polish when fully hardened; passivate in nitric or citric acid after grinding, and avoid tempering above ~400 °C which degrades corrosion resistance.
1.4125 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 X105CrMo17; GB 9Cr18Mo 0.95–1.10 | 0.95 – 1.2 | 1.05 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1 | 0.5 |
| P | ≤ 0.04 | — |
| SEN often ≤0.015 for bearing/knife quality | ≤ 0.03 | — |
| Cr | 16 – 18 | 17 |
| MoAISI 440C: Mo ≤ 0.75 | 0.4 – 0.8 | 0.55 |
| Niresidual | ≤ 0.5 | — |
| Fe | balance | — |
1.4125-QT500 — frequently asked
What is 1.4125-QT500 used for?
1.4125-QT500 is typically used for knife blades, surgical scalpels, ball bearings, wear-resistant valve parts and precision gauges. In short: hardest common stainless; 440C wear-resistance benchmark; not weldable, wear-first grade.
What is the yield strength of 1.4125-QT500?
1.4125-QT500 has a typical yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 1.4125-QT500 easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 100% of stainless steel grades). Machine only in the annealed condition with sharp carbide tooling, low speed and rigid setups; hardened parts require grinding or EDM.
Can 1.4125-QT500 be welded?
Not readily — weldability is rated not recommended (5/100). Essentially not recommended — high carbon causes cracking; if unavoidable preheat 250–350 °C, use matching or austenitic filler and immediately anneal/temper.
What surface finishes work on 1.4125-QT500?
Takes a high mirror polish when fully hardened; passivate in nitric or citric acid after grinding, and avoid tempering above ~400 °C which degrades corrosion resistance.
Can 1.4125-QT500 be formed, bent or molded?
Cold forming is very limited (annealed sheet only, generous radii); hot work 1100→850 °C followed by slow cool and spheroidize anneal.
What is the maximum service temperature of 1.4125-QT500?
1.4125-QT500 is rated for continuous use to about 420°C (788 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4125 +A and 1.4125-QT150?
+A is the default condition — standard stock condition for machining before hardening; softest and most workable state. QT150: maximum hardness with best corrosion resistance — standard for bearing races/balls and premium knife blades. Yield strength is 450 MPa in +A versus 1,930 MPa in QT150.
Sources
- EN 10088-3 Stainless steels – semi-finished products, bars, rods (X105CrMo17 / 1.4125) — CEN (2014)
- ASTM A276 / A484 Stainless Steel Bars and Shapes (Type 440C) — ASTM (2017)
- GB/T 1220 (9Cr18Mo) — SAC (2007)
- ASM Handbook Vol.1 Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Martensitic stainless bar/strip datasheets (Sandvik, Böhler N685, Aubert & Duval) — various producers (2023)
- 9Cr18Mo/440C — 1688 / Mysteel (2026)
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.