Steel H43
AISI/SAE H43 · UNS T20843
H43 is a high-molybdenum hot-work tool steel (UNS T20843) with elevated vanadium for hot hardness and wear resistance, part of the AISI H series.
Reference datasheet — H43 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
H43 tempers and conditions
H43 is supplied in 5 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
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 |
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?
H43 is a high-molybdenum hot-work tool steel (UNS T20843) with elevated vanadium for hot hardness and wear resistance, part of the AISI H series. Annealed stock runs 229 HB with 760 MPa tensile, 520 MPa yield and 18 % elongation, and it is hardened to roughly 54, 58 or 62 HRC or nitrided for extrusion dies, die-casting inserts and hot forging tooling. Service is limited to about 400 °C, and with machinability 35 and formability 12 the 8 % Mo / 2 % V carbide network must be cut annealed and finished by grinding or EDM. H13 is the standard lower-alloy alternative when toughness matters more than wear. H43 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). H43 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 67% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
What is H43 used for?
- hot extrusion dies
- die-casting inserts
- hot forging dies
- high-temperature punches
Advantages
- Polishes to a fine finish — 72/100, better than 92% of steel grades
Limitations
- Limited formability — 12/100, worse than 92% of steel grades
- High embodied carbon — 3.1 kg CO₂/kg, worse than 92% of steel grades
- Poor heat conductor — 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
- Difficult to machine — 35/100, worse than 84% of steel grades
H43 properties
Typical room-temperature values for H43-ANN; bars are the position among steel grades.
Physical3
H43 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 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 67% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
H43 is rated for continuous service to 400°C (752 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
H43 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 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's machinability is fair (35/100, worse than 84% of steel grades); weldability poor (25/100); formability not recommended (12/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. H43 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with H43
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.
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel H43 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T20843
How much does H43 cost?
H43 is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
H43 — frequently asked
What is H43 used for?
H43 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?
H43 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is H43 easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% 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 be welded?
Not readily — weldability is rated poor (25/100). 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?
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 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?
H43 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 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.
How much does H43 cost?
H43 is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.