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718 steel vs. Inconel 718: Differences and choices between the two materials
Analysis of Differences Between 718 Mold Steel and Inconel 718
718 mold steel is a non-standard grade name, also commonly referred to as "718 mold steel". It is a commercial designation for modified P20-type steel in the mold manufacturing industry. It is mainly used in medium-temperature, conventional wear and corrosion-resistant applications such as plastic injection molds.
Inconel 718, on the other hand, is a precipitation-hardening nickel-based superalloy (UNS N07718) specified in the official documentation of Special Metals Corporation (SMC). Developed by INCO in the late 1950s, "718" is merely one of its commercial serial numbers. It is widely used in aerospace and extreme high-temperature environments.
718 Mold Steel vs Inconel 718
| Comparison Item | 718 Mold Steel (Die Steel/Tool Steel) | Inconel 718 (Nickel-Based Superalloy) |
|---|---|---|
| Main Standards | Modified AISI P20China GB 3Cr2NiMo | AMS / SAE / ASTMAerospace Material System |
| Main Composition System | Iron-based alloyFe-Cr-Mn-Ni-Mo | High-nickel alloy (Ni 50~55%)Ni-Cr-Fe-Nb-Ti |
| Typical Hardness | 30~36 HRC (pre-hardened condition) | 44~50 HRC (after aging treatment) |
| Operating Temperature | ≤ 300℃ | Up to 700~800℃ |
| Core Properties | High cleanliness, good texturing performance, uniform hardnessEasy to machine and polish at room temperature | Excellent high-temperature strength and creep resistanceOxidation and corrosion resistance, maintains properties at high temperatures |
| Strengthening Mechanism | Phase transformation strengtheningNi element improves hardenabilityObtains uniform martensite/bainite structure | Precipitation strengthening (γ″ / γ′)Strengthened by precipitation of γ″-Ni₃Nb and γ′-Ni₃(Al,Ti) phases |
| Heat Treatment State | Ready-to-use pre-hardened steelDelivered in pre-hardened condition, can be directly processed into moldsNo quenching required, low deformation risk | Requires complex heat treatmentSolution treatment + two-stage aging(720℃/8h → 620℃/8h) |
| Typical Applications | Plastic injection moldsAutomotive parts, home appliance casings, electronic product housings, etc. | Load-bearing components in extreme environmentsAero-engines, rocket engines, nuclear power, high-performance racing exhaust systems |
Approximate Equivalent Standard Comparison
| Standard System | 718 Mold Steel | Inconel 718 |
|---|---|---|
| ASTM / AISI | P20 + Ni | N07718 / AMS 5596 |
| GB (China) | 3Cr2MnNiMo | GH4169 |
| YB | SM3Cr2MnNiMo | NiCr19NbMo |
| DIN / EN | 1.2738 | 2.4668 |
| ISO | 40CrMnNiMo 8-6-4 | — |
| JIS | PX5 / NAK55 | — |
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