Tungsten high-speed steel

High speed steels are highly alloyed tool steels which exhibit enhanced hardness and wear resistance at high temperatures. These steels have a high carbon content and varying amounts of chromium, molybdenum, tungsten and vanadium. 

High speed steels (HSS) consume by far the most tungsten in steelmaking, although they account for less than 0.02% of the total steel production (1997 about 700 million metric tons). In fact the tungsten story in special steel making is the story of high speed steel [8.8]. 

From an environmental standpoint, cemented carbide tools are preferable to high speed steel because any tungsten in steel is lost by dilution (see Section 11.1) in contrast to cemented carbide scrap, which is a valuable source for recycling [8.10]. 

Ductile tungsten has also been produced by electrolytic deposition.2 If WO3 is dissolved in boric acid at 1200°-1400°, the solution may be electrolyzed, the deposited tungsten being sufficiently ductile to permit drawing through dies of high speed steel lubricated with talc. 

Figure 73. Wear rates of HSS (high speed steel), WC (tungsten carbide) and pcD routers machining chipboard.

For turning CoCr alloys, tungsten carbide tools are usually applied. Ceramic coated carbide, boron nitride and high speed steels can also be used. Water soluble oils are applied as cutting fluids. Table lb.5 gives the turning parameters for CoCr-alloys. 

TC = hard metal (tungsten carbide). HSS = high speed steel. 

Tungsten-carbide cutting tools Titanium-nitride coatings on high-speed steel drill bits Silicon-carbide fibers and whiskers Boron-carbide abrasive blast nozzles... 

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