Steel 1.2842-QT400
Heat-treated state
EN 1.2842 · AISI/SAE O2
QT400 = q&T 400 °C
Low-hardness/high-toughness setting for shanks, holders and shock-loaded parts.
Values for the QT400 condition
Other 1.2842 tempers and conditions
1.2842 is listed in 9 conditions; see the grade overview at 1.2842.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft annealed (≤229 HB), as-delivered bar/flat stock | Standard supply condition for machining tools and dies before hardening. | 420 | 700 | 16 | 17 HRC | 7 % IACS |
Stress relieved | Intermediate step for large or asymmetric tools to minimise distortion during hardening. | 420 | 700 | 16 | 17 HRC | 7 % IACS |
Cold drawn / precision ground flat & round stock (annealed) | Pick for gauge and jig blanks needing tight tolerance and clean surface before hardening. | 520 | 760 | 12 | 20 HRC | 33 W/m·K |
QT400This page Q&T 400 °C | Low-hardness/high-toughness setting for shanks, holders and shock-loaded parts. | 1,450 | 1,700 | 5 | 50 HRC | 7 % IACS |
Q&T 300 °C | Tougher setting for larger tools and forming dies where chipping is the failure mode. | 1,620 | 1,900 | 3 | 55 HRC | 6.5 % IACS |
Q&T 250 °C | Choose when slightly more toughness is needed for impact-loaded punches and shear blades. | 1,780 | 2,050 | 2 | 58 HRC | 6.5 % IACS |
Hardened, as quenched | Intermediate state only — must be tempered immediately to avoid quench cracking. | 2,000 | 2,400 | 0.5 | 64 HRC | 6 % IACS |
Q&T 200 °C | Standard working hardness for blanking and trimming dies; best wear/toughness compromise. | 2,000 | 2,250 | 1 | 61 HRC | 6 % IACS |
Q&T 180 °C | Maximum hardness for gauges, punches and woodworking blades with minimal dimensional change. | — | 2,400 | — | 63 HRC | — |
What is 1.2842-QT400?
1.2842-QT400 is 1.2842 heat treated to QT400 — low-hardness/high-toughness setting for shanks, holders and shock-loaded parts. 1.2842-QT400 has a yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Elongation at break is 5% and the elastic modulus is 208 GPa (30.2 Msi). 1.2842-QT400 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). Annealed is the default condition FabDigit quotes; QT400 is available on request or by drawing note.
Advantages
- High strength — 1,450 MPa (210 ksi), better than 97% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 8/100, worse than 99% of steel grades
- Limited ductility — 5%, worse than 98% of steel grades
- Difficult to machine — 18/100, worse than 97% of steel grades
- Limited formability — 8/100, worse than 97% of steel grades
- Low fracture toughness — 30 MPa·√m (27.3 ksi·√in), worse than 96% of steel grades
1.2842-QT400 properties
Typical room-temperature values for 1.2842-QT400; 22 are specific to this condition. Other listed values are 1.2842 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
1.2842-QT400 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical17
1.2842-QT400 has a yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Elongation at break is 5% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
1.2842-QT400 is rated for continuous service to 320°C (608 °F). It conducts heat at 32 W/m·K (18.5 BTU/hr·ft·°F), worse than 82% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
1.2842-QT400 conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 1.2842-QT400 takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 35%.
Manufacturability8
1.2842-QT400's machinability is poor (18/100, worse than 97% of steel grades); weldability not recommended (8/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.2842-QT400
Is 1.2842 easy to machine?
Machine in the annealed state with sharp carbide or HSS tooling at moderate speed; after hardening only grinding, EDM or CBN work is practical.
Can 1.2842 be welded?
Not intended for structural welding; repair-weld hardened tools only with preheat 300–350 °C, matching tool-steel electrode and immediate re-temper.
Can 1.2842 be formed, bent or molded?
Cold forming is limited to mild bending of annealed thin stock; hot forge 1050→850 °C followed by slow cooling and soft annealing at 720–750 °C.
What surface finishes work on 1.2842?
Takes a good polish and fine ground finish when hardened; protect with oil, black oxide, phosphating or PVD/nitride coating since the steel has no corrosion resistance.
1.2842 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 |
|---|---|---|
| C | 0.85 – 0.95 | 0.9 |
| Si | 0.1 – 0.4 | 0.25 |
| Mngives deep oil hardenability and low distortion | 1.9 – 2.1 | 2 |
| Cr | 0.2 – 0.5 | 0.35 |
| Vgrain refinement | 0.05 – 0.2 | 0.1 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
1.2842-QT400 — frequently asked
What is 1.2842-QT400 used for?
1.2842-QT400 is typically used for gauges, jigs and fixtures and precision dies. In short: oil-hardening gauge steel; best-machining cold-work grade; O2 equivalent.
What is the yield strength of 1.2842-QT400?
1.2842-QT400 has a typical yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 1.2842-QT400 easy to machine?
Not especially — machinability is rated poor (18/100, worse than 97% of steel grades). Machine in the annealed state with sharp carbide or HSS tooling at moderate speed; after hardening only grinding, EDM or CBN work is practical.
Can 1.2842-QT400 be welded?
Not readily — weldability is rated not recommended (8/100). Not intended for structural welding; repair-weld hardened tools only with preheat 300–350 °C, matching tool-steel electrode and immediate re-temper.
What surface finishes work on 1.2842-QT400?
Takes a good polish and fine ground finish when hardened; protect with oil, black oxide, phosphating or PVD/nitride coating since the steel has no corrosion resistance.
Can 1.2842-QT400 be formed, bent or molded?
Cold forming is limited to mild bending of annealed thin stock; hot forge 1050→850 °C followed by slow cooling and soft annealing at 720–750 °C.
What is the maximum service temperature of 1.2842-QT400?
1.2842-QT400 is rated for continuous use to about 320°C (608 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.2842 Annealed and 1.2842 H-AQ?
Annealed is the default condition — standard supply condition for machining tools and dies before hardening. H-AQ: intermediate state only — must be tempered immediately to avoid quench cracking. Yield strength is 420 MPa in Annealed versus 2,000 MPa in H-AQ.
Sources
- EN ISO 4957 — Tool steels — ISO/CEN (2018)
- DIN 17350 / Werkstoff-Nr. 1.2842 (90MnCrV8) — DIN (1980)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- Oil-hardening cold-work tool steel datasheets (O2 / 90MnCrV8 class) — Böhler / Uddeholm / Buderus (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.