Pre-hardened plastic mold steels

Pre-hardened plastic mold steels (hardness -31 HRC) Hardened plastic mold steels (hardness -62 HRC) Case hardening steels (hardness -62 HRC) Surface finished steels (700-3500 HV)... 

The desired plastic forming is mostly carried out under hydraulic presses, to ensure the required material properties. After forming, the steel manufacturer carries out suitable heat treatment, which may be either preliminary heat treatment prior to machining, or final heat treatment in the case of pre-hardened plastic mold steels. 

The pre-hardened plastic mold steel 1.2312 (40CrMnMoS8-6) is not suitable for molds with high surface requirements or mechanical stresses, because of its high sulphur content. In combination with manganese, the sulphur forms long-chain sulfides that can cause the following problems ... 

Pre-hardened plastic mold steels for all standard applications (hardness range... 

FIGURE 3.6 Comparison of the through-hardenability of pre-hardened plastic mold steels... 

CrMnNiMo8-6-4). Figure 3.7 illustrates the merits of the new plastic mold steel 2738 mod. IS, which covers most applications for hardnesses up to 38 HRC, due to its chemical composition and resultant properties, helping to significantly simplify the material concept in the case of pre-hardened plastic mold steels. 

Through-hardening plastic mold steels for hardening after (pre-)machining, e.g. for molds and tools subject to high wear (hardness range 44 to 62 HRC)... 

Corrosion-resistant plastic mold steels e.g. for PVC processing, pre-hardened to approximately 30 HRC for standard applications, up to 53 HRC for high levels of wear, with hardening after (pre-)machining... 

Figure 4.90 shows an example of a plastic compression mold made of the prehardened plastic mold steel 1.2738 (40CrMnNiMo8-6-4). Cracking occurred during flame hardening of the parting lines due to the absence of pre-heating. 

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