"case hardening" meaning in English

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        "present participle and gerund of case harden"
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  "lang_code": "en",
  "pos": "noun",
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        "The process of imparting greater hardness to the surface of a piece of metal."
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        "(metallurgy) The process of imparting greater hardness to the surface of a piece of metal."
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  "word": "case hardening"
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      "word": "case-hardening"
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  "pos": "noun",
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        "The process of imparting greater hardness to the surface of a piece of metal."
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