The advantages of vacuum hardening, illustrated by the specimen parts shown in Figure 1, are highly prized in the field of toolmaking. This is because the contamination of the workpiece surface that is unavoidable in normal hardening is extremely costly and labour-intensive to remove. This problem is eliminated with vacuum hardening, with the further advantage of correct reproducible process control. Unfortunately, the process was hitherto only applicable to full-hardening steels, e.g. 1.2767 or 1.2343. The carburising of the workpiece surface before hardening that was necessary with the case hardening steels, e.g. 1.2764, was not possible with the previously available vacuum hardening systems.
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