Steel H43-QT58
Heat-treated state
AISI/SAE H43 · UNS T20843
QT58 = hardened & tempered to 58–60 HRC
The usual service condition: high hot hardness and wear resistance for hot extrusion and shear tooling.
Values for the QT58 condition
Other H43 tempers and conditions
H43 is listed in 5 conditions; see the grade overview at H43.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard mill-supplied bar condition for machining tool blanks before hardening. | 520 | 760 | 18 | 229 HB | — |
Hardened & tempered to 54–56 HRC | Choose when impact loading (hot forging dies, punches) matters more than peak wear resistance. | 1,620 | 1,900 | 3 | 55 HRC | 24 W/m·K |
Hardened, tempered and nitrided surface | Add when die surfaces suffer abrasive wear or soldering; core stays at the tempered hardness. | 1,650 | 1,960 | 3 | 59 HRC | 2.9 % IACS |
QT58This page Hardened & tempered to 58–60 HRC | The usual service condition: high hot hardness and wear resistance for hot extrusion and shear tooling. | 1,850 | 2,150 | 2 | 59 HRC | 23 W/m·K |
Hardened & tempered to 61–63 HRC | Peak secondary-hardening condition for abrasive, low-shock hot-work and cutting-type applications. | 2,000 | 2,300 | 1 | 62 HRC | 23 W/m·K |
What is H43-QT58?
H43-QT58 is H43 heat treated to QT58 — the usual service condition: high hot hardness and wear resistance for hot extrusion and shear tooling. H43-QT58 has a yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 99% of steel grades. Elongation at break is 2% and the elastic modulus is 210 GPa (30.5 Msi). H43-QT58 has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 94% of steel grades. It melts at 1,400°C (2,552 °F). ANN is the default condition FabDigit quotes; QT58 is available on request or by drawing note.
Advantages
- High strength — 1,850 MPa (268 ksi), better than 99% of steel grades
- High service temperature — 590°C (1,094 °F), better than 97% of steel grades
- Polishes to a fine finish — 75/100, better than 94% of steel grades
Limitations
- Difficult to machine — 5/100, worse than 100% of steel grades
- Limited formability — 1/100, worse than 100% of steel grades
- Limited ductility — 2%, worse than 99% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Poor heat conductor — 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 92% of steel grades
H43-QT58 properties
Typical room-temperature values for H43-QT58; 20 are specific to this condition. Other listed values are H43 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
H43-QT58 has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 94% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
H43-QT58 has a yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 99% of steel grades. Elongation at break is 2% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
H43-QT58 is rated for continuous service to 590°C (1,094 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 92% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
H43-QT58 conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of H43-QT58 takes about 42 MJ of energy and emits 3.1 kg of CO₂ — more than 92% of steel grades. Typical recycled content is 45%.
Manufacturability8
H43-QT58's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (10/100); formability not recommended (1/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with H43-QT58
Is H43 easy to machine?
Machine only in the annealed condition with rigid setups, sharp carbide or cobalt HSS tooling and reduced speeds — the 8% Mo / 2% V carbide network makes it markedly harder to cut than H13; hardened parts require grinding or EDM.
Can H43 be welded?
Repair welding only: preheat 400–500 °C, use matched or high-alloy Mo-hot-work filler, keep interpass hot and temper immediately below the last tempering temperature.
Can H43 be formed, bent or molded?
No practical cold forming; hot work between about 1050 and 900 °C with slow furnace cooling, then a full spheroidize anneal at 860–880 °C before machining.
What surface finishes work on H43?
Harden from 1100–1180 °C in vacuum or neutral salt (protect against decarburization), temper 2–3 times at 540–600 °C for secondary hardness; finish with nitriding, oxide blackening or PVD coating — no anodizing.
H43 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 |
|---|---|---|
| CASTM A681 H43 | 0.5 – 0.65 | 0.58 |
| Mn | 0.15 – 0.4 | 0.3 |
| Si | 0.15 – 0.5 | 0.35 |
| Cr | 3.75 – 4.5 | 4.1 |
| Momain secondary-hardening element | 7.75 – 8.5 | 8.1 |
| VMC carbides for wear resistance | 1.8 – 2.2 | 2 |
| Wresidual, not intentionally added | ≤ 0.5 | 0.1 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.02 |
| Fe | balance | — |
H43-QT58 — frequently asked
What is H43-QT58 used for?
H43-QT58 is typically used for hot extrusion dies, die-casting inserts, hot forging dies and high-temperature punches. In short: high-Mo, high-V hot-work grade; wear-focused H-series steel; harder to machine than H13.
What is the yield strength of H43-QT58?
H43-QT58 has a typical yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is H43-QT58 easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine only in the annealed condition with rigid setups, sharp carbide or cobalt HSS tooling and reduced speeds — the 8% Mo / 2% V carbide network makes it markedly harder to cut than H13; hardened parts require grinding or EDM.
Can H43-QT58 be welded?
Not readily — weldability is rated not recommended (10/100). Repair welding only: preheat 400–500 °C, use matched or high-alloy Mo-hot-work filler, keep interpass hot and temper immediately below the last tempering temperature.
What surface finishes work on H43-QT58?
Harden from 1100–1180 °C in vacuum or neutral salt (protect against decarburization), temper 2–3 times at 540–600 °C for secondary hardness; finish with nitriding, oxide blackening or PVD coating — no anodizing.
Can H43-QT58 be formed, bent or molded?
No practical cold forming; hot work between about 1050 and 900 °C with slow furnace cooling, then a full spheroidize anneal at 860–880 °C before machining.
What is the maximum service temperature of H43-QT58?
H43-QT58 is rated for continuous use to about 590°C (1,094 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between H43-ANN and H43-QT62?
ANN is the default condition — standard mill-supplied bar condition for machining tool blanks before hardening. QT62: peak secondary-hardening condition for abrasive, low-shock hot-work and cutting-type applications. Yield strength is 520 MPa in ANN versus 2,000 MPa in QT62.
Sources
- ASTM A681 — Standard Specification for Tool Steels Alloy — ASTM International (2022)
- SAE J437/J438 — Tool and Die Steels — SAE International (2015)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- ASM Specialty Handbook: Tool Materials — ASM International (1995)
- ASM Handbook Vol. 16 — Machining — ASM International (1989)
- UNS T20843 alloy record — SAE/ASTM Unified Numbering System (2017)
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.