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Cope, S. G. (1958) A study of carbide reactions during the tempering of high speed steels. Doctoral thesis, Sir John Cass College.
The thesis describes an attempt to define by classical methods of investigation the course of precipitation of different carbides during the tempering of high speed steels. Because of considerable recent advances in parallel studies of carbides formed in the tiering of low alloy and other steels a particularly full survey of the literature extending well beyond the confines of the research coverage itself is included.
Most of the investigations were carried out on four high speed steels of representative analysis including high vanadium types. These were studied after a wide range of tempering treatments and detailed results are quoted in respect to weight, X-ray analysis and chemical compositions of extracted carbide residues, and hardness and metallographic constitution (particularly as revealed by selective carbide etchants) of the steel itself. Supplementary work is described regarding similar experiments carried out on hot die steel and on two special high vanadium steels.
The limitations of the methods used restrict the scope of positive results from the investigation particularly in respect of the stage of tempering at which new-formed particles can be detected and identified. Nevertheless it can be claimed that a consistent pattern of precipitation of alloy carbides is revealed in all the steels examined, differences between them being only in respect of quantity and phasing. In general the indicated precipitation is in the order W2C: VC: M23C6: M6C. The form and distribution of the different carbides as revealed by optical metallography is described and discussed.
Even the earliest detection of precipitation comes at a stage of tempering well beyond the peak of secondary hardness so there is no positive indication of a source of precipitation hardening but general conditions are consistent with one or both of the carbides W2C and VC contributing in this way. The relationship between present results and those in other published work is briefly discussed.
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