Tool steels cobalt

Creaies a diffused hum (boron compoundsl case. Base nieials are alloy and tool steels cobalt- and nickel-base alloys Process temperature range is 400-1150 C (750-2100nFi. 

Fig. 5. Micrographs of the microstructure of fully hardened and tempered tool steels produced by the powder metallurgy technique, showing uniform distribution and fine carbide particles in the matrix, (a) M-42 (see Table 6) and (b) cobalt-free AlSl T-15 having a higher concentration of fine carbide...

COBALT AND ITS COMPOUNDS Cobalt, Co, at wt 58.95, steel-gray metal, d 8.71 at 20°, mp 1495°, bp 2880° readily sol in nitric acid and less sol in dil hydrochloric or sulfuric acids. It is obtained from ore concentrates by roasting, followed by thermal reduction by A1 or other methods. The principal use of the metal is in alloys, especially Co steels for permanent supermagnets, Co-Cr high-speed tool steels, cemented carbides and high temperature-resisting alloys for jet engins, For a description of its alloys see Refs 1, 2, 3, 4, 5, 6 8. Cobalt Bomb is briefly discussed under Bombs in Vol 2,... 

Cobalt (Co). Cobalt increases the hot hardness of tool steels. Substantial addition of cobalt, however, raises the critical quenching temperature of the steel with a tendency to increase the decarburization of the surface and reduces toughness. 

When chromium and nickel are combined with steel, steel becomes stainless, and it is used to make flatware and surgical tools. Steel combined with cobalt is used to make jet engines and gas turbines. 

The chief industrial attribute of the cobalt-base alloys is their resistance to wear. They hold a unique position in that they are also corrosion-resistant (when the carbon content is low), and maintain their strengths and wear resistance at high temperatures, by virtue of reasonable microstructural stability (relative to, say, the austenitic manganese steels, the tool steels, and the high-silicon stainless steels). 

A wide variety of metals is produced for industries such as automotive, aerospace, marine, energy, chemical processing, etc. Materials include aluminum, titanium, stainless steel, nickel- and cobalt-base alloys, tool steels, and materials for electronic, magnetic, and expansion applications. Regardless of the metal, the stime selection process can be used. 

Choose material couples that are resistant to interaction in sliding (metal-to-metal wear resistance). Hardfacing alloys such as cobalt-base and nickel-chromium-boron alloys have been used for many years for applications involving metal-to-metal wear. Other surfaceengineering options include through-hardened tool steels, diffusion (case)-hardened surfaces, selective surface-hardened alloy steels, and some platings. 

Weld hardfacing coatings, for example, high-carbon iron-chromium alloys, tool steels, nickel-chromium-boron alloys, cobalt-base alloys, and austenitic manganese steels... 

A wide range of cutting-tool materials is available. Properties, performance capabilities, and cost vary widely (2,7). Various steels (see Steel) cast cobalt alloys (see Cobalt and cobalt alloys) cemented, cast, and coated carbides (qv) ceramics (qv), sintered polycrystalline cubic boron nitride (cBN) (see Boron compounds) and sintered polycrystalline diamond tbin diamond coatings on cemented carbides and ceramics and single-crystal natural diamond (see Carbon) are all used as tool materials. Most tool materials used in the 1990s were developed during the twentieth century. The tool materials of the 1990s... 

Cobalt ores are often found in association with copper(II) sulfide. Cobalt is a silver-gray metal and is used mainly for alloying with iron. Alnico steel, an alloy of iron, nickel, cobalt, and aluminum, is used to make permanent magnets such as those in loudspeakers. Cobalt steels are hard enough to be used as surgical steels, drill bits, and lathe tools. The color of cobalt glass is due to a blue pigment that forms when cobalt(II) oxide is heated with silica and alumina. 

---