Steel H19 QT50-52
Hardness band
AISI/SAE H19 · UNS T20819
QT50-52 = hardened & tempered 50–52 HRC
The usual delivered working condition: austenitize ~1150–1200 °C, quench, double temper ~590–620 °C for best hot hardness/toughness balance.
Values for the QT50-52 condition
Other H19 tempers and conditions
H19 is listed in 5 conditions; see the grade overview at H19.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard stock condition for bar and block: soft enough for rough machining before hardening. | 520 | 800 | 18 | 20 HRC | — |
Hardened & tempered 44–48 HRC | Pick for hot forging dies and extrusion tooling where thermal-fatigue cracking, not wear, is the failure mode. | 1,300 | 1,500 | 10 | 46 HRC | — |
QT50-52This page Hardened & tempered 50–52 HRC | The usual delivered working condition: austenitize ~1150–1200 °C, quench, double temper ~590–620 °C for best hot hardness/toughness balance. | 1,520 | 1,750 | 8 | 51 HRC | 25 W/m·K |
Hardened, tempered and gas/plasma nitrided | Surface-engineered condition for die-casting and extrusion inserts needing washout/soldering resistance over a 50–52 HRC core. | 1,520 | 1,750 | 7 | 51 HRC | — |
Hardened & tempered 54–57 HRC | Choose for hot punches, shear blades and hot-work tools where abrasion and hot compressive strength dominate and impact loading is low. | 1,720 | 1,980 | 5 | 55 HRC | — |
What is H19 QT50-52?
H19 QT50-52 is H19 heat treated to QT50-52 — the usual delivered working condition: austenitize ~1150–1200 °C, quench, double temper ~590–620 °C for best hot hardness/toughness balance. H19 QT50-52 has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,750 MPa (254 ksi) — stronger than 97% of steel grades. Elongation at break is 8% and the elastic modulus is 210 GPa (30.5 Msi). H19 QT50-52 has a density of 8.19 g/cm³ (0.296 lb/in³), heavier than 98% of steel grades. It melts at 1,370°C (2,498 °F). ANN is the default condition FabDigit quotes; QT50-52 is available on request or by drawing note.
Advantages
- High service temperature — 620°C (1,148 °F), better than 99% of steel grades
- High strength — 1,520 MPa (220 ksi), better than 97% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to machine — 10/100, worse than 99% of steel grades
- Limited formability — 3/100, worse than 99% of steel grades
- Low electrical conductivity — 2.7 % IACS, worse than 96% of steel grades
- Limited ductility — 8%, worse than 95% of steel grades
- High embodied carbon — 3.2 kg CO₂/kg, worse than 92% of steel grades
H19 QT50-52 properties
Typical room-temperature values for H19 QT50-52; 21 are specific to this condition. Other listed values are H19 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
H19 QT50-52 has a density of 8.19 g/cm³ (0.296 lb/in³), heavier than 98% of steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
H19 QT50-52 has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,750 MPa (254 ksi) — stronger than 97% of steel grades. Elongation at break is 8% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
H19 QT50-52 is rated for continuous service to 620°C (1,148 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 11.2 µm/m·K (6.22 µin/in·°F).
Electrical3
H19 QT50-52 conducts electricity at 2.7 % IACS, worse than 96% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of H19 QT50-52 takes about 45 MJ of energy and emits 3.2 kg of CO₂ — more than 93% of steel grades. Typical recycled content is 40%.
Manufacturability8
H19 QT50-52's machinability is not recommended (10/100, worse than 99% of steel grades); weldability poor (18/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with H19 QT50-52
Is H19 easy to machine?
Machine only in the annealed state with rigid setups, sharp carbide or coated carbide at reduced speed — the W/V carbides are abrasive and tool life is roughly a third of 4140; finish hardened parts by grinding or EDM (re-temper after EDM).
Can H19 be welded?
Repair-weld with matching hot-work filler at 400–500 °C preheat, maintain interpass temperature, and temper immediately at ~25 °C below the last tempering temperature to avoid cracking.
Can H19 be formed, bent or molded?
Hot work at 1050–1150 °C, never below ~900 °C, then slow-cool and fully anneal at ~870–900 °C; cold forming is not practical.
What surface finishes work on H19?
Not anodizable; use nitriding, oxidizing/blackening, or PVD CrN/AlTiN on the tempered surface, and keep tempering above the coating deposition temperature to avoid softening.
H19 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 | 0.32 – 0.45 | 0.4 |
| Mn | 0.2 – 0.5 | 0.3 |
| Si | 0.2 – 0.5 | 0.3 |
| Cr | 4 – 4.75 | 4.25 |
| W | 3.75 – 4.5 | 4.25 |
| Cogives the red-hardness advantage over H10–H13 | 4 – 4.5 | 4.25 |
| V | 1.75 – 2.2 | 2 |
| Mo | 0.3 – 0.55 | 0.4 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
H19 QT50-52 — frequently asked
What is H19 QT50-52 used for?
H19 QT50-52 is typically used for hot extrusion tooling, hot shear blades, piercer points and high-temperature forging dies. In short: highest red hardness in H10–H19; cobalt-alloyed hot-work grade; tougher alternative is H13.
What is the yield strength of H19 QT50-52?
H19 QT50-52 has a typical yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,750 MPa (254 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is H19 QT50-52 easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 99% of steel grades). Machine only in the annealed state with rigid setups, sharp carbide or coated carbide at reduced speed — the W/V carbides are abrasive and tool life is roughly a third of 4140; finish hardened parts by grinding or EDM (re-temper after EDM).
Can H19 QT50-52 be welded?
Not readily — weldability is rated poor (18/100). Repair-weld with matching hot-work filler at 400–500 °C preheat, maintain interpass temperature, and temper immediately at ~25 °C below the last tempering temperature to avoid cracking.
What surface finishes work on H19 QT50-52?
Not anodizable; use nitriding, oxidizing/blackening, or PVD CrN/AlTiN on the tempered surface, and keep tempering above the coating deposition temperature to avoid softening.
Can H19 QT50-52 be formed, bent or molded?
Hot work at 1050–1150 °C, never below ~900 °C, then slow-cool and fully anneal at ~870–900 °C; cold forming is not practical.
What is the maximum service temperature of H19 QT50-52?
H19 QT50-52 is rated for continuous use to about 620°C (1,148 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between H19-ANN and H19 QT54-57?
ANN is the default condition — standard stock condition for bar and block: soft enough for rough machining before hardening. QT54-57: choose for hot punches, shear blades and hot-work tools where abrasion and hot compressive strength dominate and impact loading is low. Yield strength is 520 MPa in ANN versus 1,720 MPa in QT54-57.
Sources
- ASTM A681 — Standard Specification for Tool Steels Alloy — ASTM International (2022)
- SAE AMS 6455 / UNS T20819 designation data — SAE International (2020)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Hot-Work Tool Steels) — ASM International (1990)
- ASM Handbook Vol.16: Machining (machinability ratings of tool steels) — ASM International (1989)
- Tool Steels, 5th Edition (Roberts, Krauss, Kennedy) — ASM International (1998)
- Hot-work tool steel heat-treatment and property bulletins — Böhler / Crucible / Carpenter (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.