Steel A4 HT54-56
Hardness band
AISI/SAE A4 · UNS T30104
HT54-56 = hardened & tempered 54–56 HRC
Higher-toughness setting for shock-loaded punches, shear blades and heavier forming tools.
Values for the HT54-56 condition
Other A4 tempers and conditions
A4 is listed in 5 conditions; see the grade overview at A4.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard mill supply condition for machining tool blanks before hardening. | 415 | 745 | 20 | 225 HB | — |
HT54-56This page Hardened & tempered 54–56 HRC | Higher-toughness setting for shock-loaded punches, shear blades and heavier forming tools. | 1,560 | 1,800 | 4 | 55 HRC | — |
Hardened & tempered 57–59 HRC | Balanced hardness/toughness setting for general blanking, forming and gauging tools. | 1,700 | 1,950 | 2.5 | 58 HRC | — |
Hardened + deep cryogenic treatment + double temper | Choose for gauges and precision dies where retained austenite must be eliminated for long-term size stability. | 1,800 | 2,050 | 1.5 | 60 HRC | — |
Hardened & tempered 60–62 HRC | Maximum hardness and wear resistance for blanking and forming dies where impact loads are low. | 1,850 | 2,100 | 1.5 | 61 HRC | 24 W/m·K |
What is A4 HT54-56?
A4 HT54-56 is A4 heat treated to HT54-56 — higher-toughness setting for shock-loaded punches, shear blades and heavier forming tools. A4 HT54-56 has a yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 98% of steel grades. Elongation at break is 4% and the elastic modulus is 205 GPa (29.7 Msi). A4 HT54-56 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). ANN is the default condition FabDigit quotes; HT54-56 is available on request or by drawing note.
Advantages
- High strength — 1,560 MPa (226 ksi), better than 98% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Limited formability — 4/100, worse than 99% of steel grades
- Limited ductility — 4%, worse than 98% of steel grades
- Low electrical conductivity — 2.7 % IACS, worse than 96% of steel grades
- Difficult to weld — 12/100, worse than 96% of steel grades
A4 HT54-56 properties
Typical room-temperature values for A4 HT54-56; 18 are specific to this condition. Other listed values are A4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A4 HT54-56 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).
Mechanical15
A4 HT54-56 has a yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 98% of steel grades. Elongation at break is 4% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A4 HT54-56 is rated for continuous service to 350°C (662 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
A4 HT54-56 conducts electricity at 2.7 % IACS, worse than 96% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A4 HT54-56 takes about 36 MJ of energy and emits 2.8 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 45%.
Manufacturability8
A4 HT54-56's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (12/100); formability not recommended (4/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A4 HT54-56
Is A4 easy to machine?
Machine fully in the annealed condition (≈60 % of AISI 1212) with rigid setups and sharp carbide or cobalt HSS; after hardening only grinding, EDM or hard-turning with CBN is practical.
Can A4 be welded?
Weld only for repair: preheat/maintain 200–300 °C, use matched tool-steel or Fe-Cr-Mo filler, minimal stringer beads, then temper immediately at 15–25 °C below the prior tempering temperature.
Can A4 be formed, bent or molded?
Hot work at 900–1050 °C with slow cooling and full anneal at 740–760 °C (furnace cool 15 °C/h to 540 °C); cold forming is limited to light bending of annealed thin stock.
What surface finishes work on A4?
Takes a fine ground and lapped finish at 58–62 HRC; protect with black oxide, phosphate, nitriding or TiN/CrN PVD (below the tempering temperature) since bare surfaces rust quickly.
A4 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 | 0.95 – 1.05 | 1 |
| Mnhigh Mn gives deep air-hardening at low austenitizing temperature | 1.8 – 2.2 | 2 |
| Si | ≤ 0.5 | 0.3 |
| Cr | 0.9 – 2.2 | 1.1 |
| Mo | 0.9 – 1.4 | 1.1 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
A4 HT54-56 — frequently asked
What is A4 HT54-56 used for?
A4 HT54-56 is typically used for thick-section blanking dies, forming dies, gauges and cold work punches. In short: deeper hardening than A2; air hardening, low distortion; for heavy die sections.
What is the yield strength of A4 HT54-56?
A4 HT54-56 has a typical yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 98% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A4 HT54-56 easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine fully in the annealed condition (≈60 % of AISI 1212) with rigid setups and sharp carbide or cobalt HSS; after hardening only grinding, EDM or hard-turning with CBN is practical.
Can A4 HT54-56 be welded?
Not readily — weldability is rated not recommended (12/100). Weld only for repair: preheat/maintain 200–300 °C, use matched tool-steel or Fe-Cr-Mo filler, minimal stringer beads, then temper immediately at 15–25 °C below the prior tempering temperature.
What surface finishes work on A4 HT54-56?
Takes a fine ground and lapped finish at 58–62 HRC; protect with black oxide, phosphate, nitriding or TiN/CrN PVD (below the tempering temperature) since bare surfaces rust quickly.
Can A4 HT54-56 be formed, bent or molded?
Hot work at 900–1050 °C with slow cooling and full anneal at 740–760 °C (furnace cool 15 °C/h to 540 °C); cold forming is limited to light bending of annealed thin stock.
What is the maximum service temperature of A4 HT54-56?
A4 HT54-56 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A4-ANN and A4 HT60-62?
ANN is the default condition — standard mill supply condition for machining tool blanks before hardening. HT60-62: maximum hardness and wear resistance for blanking and forming dies where impact loads are low. Yield strength is 415 MPa in ANN versus 1,850 MPa in HT60-62.
Sources
- ASTM A681 — Standard Specification for Tool Steels Alloy — ASTM International (2022)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- ASM Handbook Vol. 16: Machining — ASM International (1989)
- UNS T30104 alloy record — SAE/ASTM Unified Numbering System (2019)
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.