The Development of High Hard and 
Tough Matrix Type High Speed Tool Steels 
By SHUN-SUKE NAKAHAMA*1, YUKINORI MATSUDA*2, KUNIO NAMIKI*3, KOZO OZAKI*4

4. Special features of DRM steels

4.1 Features of DRM steels 

Special features of DRM steels are shown in Table 3 (below). DRM1 is applied mainly to hot and warm forging dies because of its high hot hardness. DRM2 is suitable for warm and cold forging dies. Due to its high fatigue strength cold forging dies is the most appropriate applicable field. DRM3 is cold forging die steel which can be applied where AISI D2 and M2 have problems in strength and toughness.9~ As shown in Fig. 14 with the axes: toughness and strength, DRM steels show higher toughness than conventional type MHS steels and are positioned between hot, cold and high speed tool steels.

Table 3 Special Features of DRM steels

Grade	Hardware(HRC)	Applications
DRM1	56~58	Hot and warm working tools: High hard hot forging tools.
DRM2	58~62	Warm and cold working tools: High tough cold forging tools.
DRM3	62~66	Cold working tools: When AISA D2 and M2 have problems with strength and toughness.

The primary feature of DRM steels is fine microstructure as shown in Fig. 15. DRM1 and 2 scarcely show the coarse carbides compared to conventional MHS steel, MH85. DRM3 realizes uniformly dispersed carbides and contains less coarse carbides than AISI M2.

Sample: Taken from the center of 100mm dia. bar, 
Etchant: 1%Cr2O3 electrolytic etching

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