A study of the microstructure and wear of high speed steels.

Doctoral thesis English OPEN
El-Rakayby, AM
  • Subject: other

The present work describes the successful extraction of\ud the secondary hardening carbides of high speed steels, which\ud allowed the identification of these carbides by crystalloqraphic,\ud and microanalysis techniques. The secondary hardening\ud carbide of high speed steels was found to be the-cubic M2C\ud carbide and not the MC carbide as previously claimed. The\ud secondary kic carbide was found to precipitate in the\ud over-tempered state well beyond peak hardness. The sequence of\ud secondary carbide precipitation has been determined. The\ud relation between wear resistance and hardness of high speed\ud steels has been found to be non-linear due to microstructural\ud changes at and beyond peak hardness. However, primary carbides\ud of the MC and M6C types of carbides were found to be stable\ud during tempering, of these steels. It has been shown that the\ud primary carbides did not contribute to the wear resistance of\ud steels tempered to peak hardness. -However, the primary\ud carbides were found to contribute to the wear rate of\ud over-tempered steels due to their abrasive role.
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