4Cr5MoSiV Hot Work Tool Steel
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4Cr5MoSiV is a Chinese national standard grade, equivalent to AISI H11 in the United States. Compared with 4Cr5MoSiV1(AISI H13/DIN 1.2343), the vanadium content in the composition of 4Cr5MoSiV is lower. 4Cr5MoSiV1 generally has higher hot strength and hardness, and is more widely used, but 4Cr5MoSiV is still favored for high-speed hammer forging dies due to its excellent thermal fatigue resistance.
1. Chemical Composition(GB / T 1299—2000)
| C | Si | Minnesota | Cr | Mes | V | P | S |
| 0.33 – 0.43% | 0.80 – 1.20% | 0.20 – 0.50% | 4,75 – 5,50% | 1.10 – 1.60% | 0,30 – 0,60% | ≤0,030% | ≤0,030% |
2. Physical Properties of 4Cr5MoSiV
2.1 Critical Temperatures
| Punto crítico | C.A₁ | C.A₃ | Arkansas₁ | Arkansas₃ | EM | Mf |
| Temperature (approx.) / °C | 853 | 912 | 720 | 773 | 310 | 103 |
2.2 Coeficiente de expansión lineal
| Temperatura / °C | 20 ~ 100 | 20 ~ 200 | 20 ~ 300 | 20 ~ 400 | 20 ~ 500 | 20 ~ 600 | 20 ~ 700 |
| Coeff. of Linear Expansion α / 10⁻⁶ °C⁻¹ | 10.0 | 10.9 | 11.4 | 12.2 | 12.8 | 13.3 | 13.6 |
2.3 Conductividad térmica
| Temperatura / °C | 100 | 200 | 300 | 400 | 500 | 600 | 700 |
| Thermal Conductivity λ / [W/(m·K)] | 25.9 | 27.6 | 28.4 | 28.0 | 27.6 | 26.7 | 25.9 |
2.4 Módulo de elasticidad
| Temperatura / °C | 20 | 100 | 200 | 300 | 400 | 500 |
| Modulus of Elasticity E / MPa | 227,000 | 221,000 | 216,000 | 208,000 | 200,000 | 192,000 |
2.5 Density and Specific Heat Capacity
| Densidad / (g/cm³) | Capacidad calorífica específica cₚ (20°C) / [J/(kg·K)] |
| 7.69 | 459.8 |
3. Hot Forging Process Specification for 4Cr5MoSiV Steel
| Artículo | Temperatura de calentamiento / °C | Temperatura inicial de forjado / °C | Temperatura final de forjado / °C | Método de enfriamiento |
| Lingote de acero | 1140 ~ 1180 | 1100 ~ 1150 | ≥900 | Sand cooling or pit cooling |
| Lingote de acero | 1120 ~ 1150 | 1070 ~ 1100 | 850 ~ 900 | Sand cooling or pit cooling |
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4. Heat Treatment of 4Cr5MoSiV
4.1 Precalentamiento
| Plan preliminar de tratamiento térmico | Parámetros del proceso |
| Recocido posterior al forjado | Heating temperature 860 ~ 890°C, hold for 2 ~ 4h; furnace cool to below 500°C then air cool. Hardness after annealing ≤229HBW. |
| Recocido para aliviar el estrés | Heating temperature 730 ~ 760°C, hold for 3 ~ 4h, furnace cool or air cool. |
4.2 Enfriamiento
① Especificación del proceso de temple recomendado
| Quenching Temperature / °C | Quenching Medium | Quenching Medium Temperature / °C | Subsequent Step | Dureza HRC |
| 1000 ~ 1030 | Oil or Air | 20 ~ 60 | Cool to oil temperature | 53 ~ 55 |
② Relationship between Quenching Temperature and Hardness
| Quenching Temperature / °C | 950 | 975 | 1000 | 1025 | 1050 | 1075 | 1100 |
| Dureza HRC | 51 | 53 | 54.5 | 56 | 58 | 58.5 | 57.5 |
4.3 Templado
① Especificación del proceso de templado recomendado
| Propósito del templado | Temperatura / °C | Equipment | Enfriamiento | Número de temperamentos | Dureza HRC |
|---|---|---|---|---|---|
| Eliminate stress and reduce hardness | 530 ~ 580 | Molten salt bath furnace or air furnace | Air cool | 2 | 47 ~ 49 |
Note: The second tempering temperature is usually 20 ~ 30°C lower than the first.
② Mechanical Properties after Tempering at Different Temperatures
| Tempering Temperature / °C | 500 | 550 | 600 | 650 |
|---|---|---|---|---|
| Dureza HRC | 57 | 54.5 | 46.5 | 37 |
| aᴋ / (J/cm²) | 20 | 45 | 60 | 66 |
Note: 1000°C air cool, 580°C temper.
4.4 Recommended Surface Strengthening Treatment Process Specification
| Proceso | Temperatura / °C | Time / h | Medio | Layer Thickness / mm | Surface Hardness HV |
|---|---|---|---|---|---|
| Nitruración | 560 | 2 | KNO₃ 50% + NaNO₃ 50% (Mass Fraction) | 0.04 | 640 ~ 690 |
| Nitruración | 580 | 8 | Natural Gas + Ammonia | 0.25 ~ 0.30 | 830 ~ 860 |
| Nitruración | 540 | 12 ~ 20 | Ammonia decomposition rate 30% ~ 60% | 0.15 ~ 0.20 | 550 ~ 750 |
5. Propiedades mecánicas
4Cr5MoSiV (H11) steel is an air-cooling hardening type hot-work tool steel. It has good toughness, and after heat treatment strengthening, its strength can reach over 2070 MPa. Because it can be hardened in air, quenching deformation and residual stress are small, and the tendency for surface oxidation is also small. It can produce a secondary hardening phenomenon and can achieve optimal performance when tempered above 510°C. After high-temperature tempering, most of the internal stress can be eliminated. It has good thermal stability and can resist the erosion of molten aluminum alloy. Below 650°C, it has high ductility, impact toughness, oxidation resistance, thermal fatigue resistance, as well as high creep strength and tensile strength.
5.1 High-Temperature Mechanical Properties
| Test Temperature / °C | Rₘ / MPa | Rₑₗ / MPa | A (%) | Z (%) |
| 300 | 1504 | 1311 | 12.0 | 39.1 |
| 600 | 895 | 794 | 21.9 | 72.9 |
| 650 | 471 | 402 | 33.1 | 85.5 |
| 700 | 226 | 179 | 55.0 | 94.5 |
5.2 High-Temperature Hardness
| Test Temperature / °C | 300 | 450 | 600 | 650 | 700 | 750 |
|---|---|---|---|---|---|---|
| Hardness HV | 491.5 | 448.5 | 384.0 | 302.5 | 227.5 | 178.5 |
Note: Original hardness of the specimen 49~50HRC.
5.3 High-Temperature Impact Toughness
| Test Temperature / °C | 300 | 600 | 650 | 700 |
|---|---|---|---|---|
| Impact Absorption Energy K / J | 28.8 | 31.0 | 36.5 | 70.0 |
5.4 Thermal Fatigue Performance
| Calificación | |
|---|---|
| 20 ~ 650°C repeated 1000 times | 8.2 |
| 20 ~ 750°C repeated 1000 times | 14.6 |
5.5 Thermal Wear Resistance
4Cr5MoSiV Steel Thermal Wear Resistance (I)
| Rotations/times | 300 | 600 | 900 | 1200 | 1500 | 2500 |
|---|---|---|---|---|---|---|
| Pérdida de peso / mg | 0.67 | 0.80 | 1.4 | 1.63 | 1.97 | 2.62 |
Note: Test temperature 800 ~ 850°C, pressure 784 ~ 882N, specimen hardness 49 ~ 50HRC.
Table 5-89 4Cr5MoSiV Steel Thermal Wear Resistance (II)
| Rotations/times | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 1000 |
|---|---|---|---|---|---|---|---|---|
| Pérdida de peso / mg | 0.77 | 1.67 | 2.50 | 3.47 | 4.33 | 4.90 | 5.60 | 7.40 |
Note: Test temperature 910 ~ 950°C, pressure 1784 ~ 1813N, specimen hardness 49 ~ 50HRC.
5.6 Tempering Resistance
| Temperatura / °C | 500 (Secondary Hardening Peak Temperature) | 560 | 615 | 600 | 653 |
|---|---|---|---|---|---|
| Dureza HRC | 55.0 (Highest Secondary Hardening Hardness) | 49.0 | 42.0 | 36.0 | 35.0 |
Note: Specimen quenched in oil at 1020°C, hardness 59~60HRC.
5.7 Thermal Corrosion Resistance
| Test Temperature and Time | 620°C × 4h | 680°C × 4h |
|---|---|---|
| Weight Loss / (g/dm²) | 4.4188 | 16.4 |
5.8) Fatigue Limit
| Test Temperature / °C | Temperatura ambiente | 300 | 400 | 450 | 500 |
|---|---|---|---|---|---|
| σ-1 / MPa | 880 | 680 | 640 | 630 | 610 |
| σ-1k / MPa | 570 | 440 | 430 | — | 420 |
5.9 Thermal Stability of 4Cr5MoSiV Steel at 620°C
| Holding Time / h | 2 | 4 | 6 | 8 | 11.5 | 14.5 | 17.5 | 21 |
|---|---|---|---|---|---|---|---|---|
| Dureza HRC | 39.4 | 38.4 | 36.9 | 35.1 | 34.4 | 33.2 | 32.6 | 32.3 |
Note: Original hardness of the specimen was 49.9 HRC.
6. Aplicaciones
4Cr5MoSiV (H11) steel is commonly used for manufacturing die-casting molds for aluminum castings, hot extrusion dies, tools and core rods for piercing, press forging dies, plastic molds, etc. Additionally, due to its good medium-temperature strength, it is also used for manufacturing structural components for aircraft, rockets, and parts for steam turbines and gas turbines.