Steel high-speed

High speed steels were discovered in 1868 and were developed from 1898 onwards. These derive their name from their capacity to preserve their hardness (until about 600°C) while cutting material at high speed. These are steels which can be hardened by heat treatment up to 1,000 HV (Vickers Hardness) or 65-70 HRC (Rockwell C Hardness). These steels are certainly not ceramics, but they cannot be ignored here on account of their properties, their operating techniques and the presence of reinforcing precipitates (carbides in particular). 

T able 9.1. Physical and mechanical properties of hard and superhard materials 

H microhardness (GNm i ) at ambient temperature K Knoop, V Vickers RB reaction bonded  

Kic critical stress intensity factor (MPa ) at ambient temperature  

We can classify high speed steels into two types (in this whole chapter, by content we refer to the weight content)  

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Parameter Carbon and low—medium aHoy steels High speed steels Cast cobalt alloys Carbides Cemented Coated Ceramics Polycrystalline cBN Diamond... 

HSS = high speed steel cBN = cubic boron nitride. DCL = depth of cut line. 

High Speed Steels. Toward the latter part of the nineteenth century, a new he at-treatment technique for tool steels was developed in the United States (3,17) that enabled increased metal removal rates and cutting speeds. This material was termed high speed steel (HSS) because it nearly doubled the then maximum cutting speeds of carbon—low alloy steels. Cemented carbides and ceramics have since surpassed the cutting speed capabiUties of HSS by 5—15 times. 

Table 5. Chemical Composition of High Speed Steels...

High hardness (molybdenum base) cobalt high speed steels ... 

J. T. Berry, Recent Developments in the Processing of High-Speed Steels, Climax Molybdenum Co., Greenwich, Coim., 1970. 

The greatest use of cubic boron nitride is as an abrasive under the name Bora2on, in the form of small crystals, 1—500 p.m in si2e. Usually these crystals are incorporated in abrasive wheels and used to grind hard ferrous and nickel-based alloys, ranging from high speed steel tools and chilled cast-iron to gas turbine parts. The extreme hardness of the crystals and their resistance to attack by air and hot metal make the wheels very durable, and close tolerances can be maintained on the workpieces. 

Fig. 3.23. Scanning SIMS image of the carbide structure of a high-speed steel [3.52]. In the V distribution different phases (MC and M2C) are visible. The Al distribution shows the shell struc-...

Fig. 3.25. 3D SIMS measurement ofthe V distribution in high-speed steel Dimension 150 X 150 X 10 pm top block view, bottom ...

Steel alloyed with 1% A1 is more resistant to oxidation at high temperatures. The macro- and microscopic homogeneity of the distribution of all elements is better for powder metallurgical, hot isostatically pressed steels. Combining these advantages should result in better performance of high-speed steels. 

Schnell-analyse, /. rapid analysis, -arbelts-stahl, m. high-speed steel, -aufldser, m. 

It machines in a similar manner to soft copper, and high-speed-steel tools with high cutting speeds are most satisfactory. Trichloroethane is recommended as a cutting medium and the work must be kept well flooded at all... 

Machining Tantalum is readily machined using high-speed-steel tools, provided a lubricant such as trichloroethane is employed. 

Relative Cutting Performance of Coatings for High-speed Steel Tools... 

This procedure has been utihzed to determine metal cations and anions in water sample [48,50,51], titanium in high-speed steel at a concentration level of 25 3 mg/g [22], heavy metals (20 to 400 mg/1) in electroplating waste waters [25], copper and nickel (5 mg/1) in metal electroplating baths on wedge-shaped plates [44], copper, lead, cadmium, or mercury in vegetable juices [29], and nickel (1 to 3.8 mg/1) in electroplating waste water of lock industries [42,47]. 

De Morais NLPA, Brett CMA (2002) Influence of power ultrasound on the corrosion of aluminium and high speed steel. J Appl Electrochem 32 653-660... 

Karlsson, N. Metallic Oxides with the Structure of High-speed Steel Carbide. 

Gas Atomization 50-300 Standard deviation 1.9-2.5 <10-50 at high gas pressures with close-coupled atomizer Solder materials. Precious metals, Cu, Fe, Al, Mg, Co, Ti, Zn, Al-6Cr-3Fe-2Zr alloy. Low-alloy steels. High speed steels. Stainless steels, Specialty alloys, Ni-base superalloys, Alumina, Intermetallics io3-.o5 1-70 Spherical smooth particles. Cleanliness, Rapidly-solidified structures, Acceptable production rates High cost, Low 1 volume, Low energy efficiency (EE), Gas-filled porosity in particles H... 

Oil Atomization 50-70 Broad size distribution High speed steels, Bearing steels 103-10S >125 -3 Low oxidation C pick-up. Medium EE, Shape... 

Carbon and glass fibres are very abrasive and quickly wear away high-speed steel tools. For intensive use, carbide or diamond tools are preferable. 

Uses. Alloys carbides high-speed steels paints, electroplating... 

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