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Pre hardening ex factory: after forging, quenching, tempering and pre hardening to HRC38-44, there is no need for overall quenching, direct cutting and processing, and the production cycle is shortened.
Excellent cutting performance: sulfur-containing improved formula, uniform forging structure, easy milling, drilling, and precision machining, reducing processing costs.
Dense forging structure: After multi-directional upsetting and drawing forging, the carbide distribution is uniform, the toughness is good, the internal stress is small, and it is not easy to deform and crack.
Strong heat fatigue resistance: It has excellent high-temperature strength and resistance to cold and hot alternation, suitable for aluminum and zinc alloy die-casting conditions.
Good polishing and stability: high forging purity, uniform material, good surface polishing effect, and longer mold service life.
China: 4Cr5MoSiV+S
Japan: FDAC
element | C | Si | Mn | Cr | V | Mo | S | P |
scope | 0.33~0.42 | 0.80~1.20 | 0.55~0.75 | 4.8-5.5 | 0.3~0.8 | 1.2~1.6 | 0.10-0.15 (Free-cutting) | ≤0.03 |
Performance items | unit | Longitudinal (L) | Horizontal (T) | Remark |
Rockwell hardness | HRC | 39–44 | 39–44 | Factory pre-hardened |
0.2% yield strength | MPa | 1060 | ≈1000 | |
tensile strength | MPa | 1240 | ≈1180 | |
Elongation (δ) | % | 11 | 8–10 | |
Reduction of area (ψ) | % | 20 | 15–18 | |
Charpy impact toughness (U-notch) | J/cm² | 19 | 10 | 23℃ |
Thickness: 100-350mm
Width: 160-1200mm
Smelting and billets
Route: Electric furnace+LF+VD+ESR electric slag remelting, high purity, low inclusions.
Billet: Steel ingot/square billet, first annealed (800-850 ℃ insulation for 2 hours furnace cooling), hardness ≤ 220HB.
Heating specifications (crack prevention+fine grain size)
Preheating: 750-800 ℃, insulation for 1-1.5 hours (high alloy thermal conductivity difference).
Initial forging: Steel ingot at 1140-1180 ℃; Steel billet 1120-1150 ℃.
Final forging: ≥ 850 ℃ (easy to crack if too low, coarse grain if too high).
Forging deformation (three upsetting and three pulling, homogenization)
Total forging ratio: ≥ 4 (high-quality ≥ 5), crushing carbides and improving segregation.
Forging: lightly press down (30-40mm) to prevent surface cracking.
Main forging: repeated upsetting+elongation+uniform deformation on 6 sides, with a deformation ratio of ≤ 2 each time; If necessary, intermediate reheating (850-900 ℃, 2-4 hours) should be carried out to prevent cracking.
Final forging: Steel plate shaping, final forging ≥ 850 ℃.
Cooling after forging (must be slow to prevent heart cracking)
Air cool to 600-650 ℃, immediately enter the insulation pit/sand cooling, slow cool for ≥ 48 hours, and exit the pit ≤ 150 ℃.
Pre hardening treatment: 850-900 ℃ insulation → oil cooling → 550-620 ℃ secondary tempering, hardness HRC38-44.
Metallography: Fine grained martensite+dispersed carbides, without obvious band segregation.
Hardness: annealed HB180-210 after forging; Pre hardened HRC38-44; Quenching and tempering HRC50-55.
Key performance: easy cutting (S element), heat fatigue resistance, high temperature stability, maintaining HRC42+at 500 ℃.
Die casting mold: aluminum/zinc/magnesium alloy small and medium-sized precision cavity (3C, automotive small parts), no heat treatment, short cycle.
Hot forging die: Small gears and connecting rods are hot forged with good toughness and are not easily cracked.
Extrusion die: Aluminum profile extrusion die pad and sleeve, with sufficient high-temperature strength.
Plastic mold: high hardness and wear-resistant parts (driver tube, inlay), with good polishing performance.
