In order to research the carbides reaction in high speed steel, the authors already reported some experimented results on low-W and high-W steel (Tetsu-to-Hagané, (1958), p. 1186, (1959), p. 608).
In this report, a study was made on the chemical composition, the crystalline structure, and the particle size of carbides which had been electrolytically isolated from several heat-treated high-W high-Co high speed steels (X000).
The following results were obtained:
In the as-annealed the amount of carbides were 26%. Carbides which were consisted of three structures M6C, M23C6 and MC, were granulated. Main chemical composition of carbides were W (60%), Fe (20%), and, of course, Cr, Mo, Co etc. were also included.
As for the concentration of elements into carbides, that of W was 98%, that of V was 81%, but that of Cr, though it was an easy element of making up carbides, was 60%. And a lot of Mn was dissolved in matrix.
In the quenched state, the amount of insoluble carbides were about 45%, and the most portion of carbides were of M6C.
In the tempered state, small size carbides were precipitated therein. Especially, the amount of precipitation was increased suddenly by tempering at 575...
At the higher tempering temperature, X-ray diffraction lines were divided into doublets. This indicatted that there were precipitated two kind of M6C, Fe4W2C and Fe3W3C, the lattice constants of which lay near to each other. And by tempering at 750.., M23C6 was precipitated, too. The changes of the lattice constant α0 resembled to that in high W steel.