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 M
6C, M
23C
6 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 M
6C.
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 M
6C, Fe
4W
2C and Fe
3W
3C, the lattice constants of which lay near to each other. And by tempering at 750.., M
23C
6 was precipitated, too. The changes of the lattice constant α
0 resembled to that in high W steel.
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