Wear-resistant steels

A steel qualilies as an alloy steel when the manganese specified is within the limits of 1.65-2.10 7. Manganese is of major importance in increasing hardenabilily—the depth of hardness penetration after quenching. Thirteen percent manganese steel is widely used us a wear-resistant steel. 

Punches manufactured from high carbon/high chromium steel may exhibit improved wear resistance characteristics, however under extreme compression force, the cup may crack due to the brittle nature of the steel. Steels with lower carbon and chromium levels will act conversely. While these steels may be useful in some applications, the majority will require a more moderate balance of toughness and wear resistance. Steel selection for dies is not as critical. In most cases, high wear resistance steel is preferred. 

Tool steels are a diverse family with high carbon and high alloy contents. They are the strongest, hardest and most wear resistant steels, but lack toughness and weldability. Tool steels are designed for specific uses and are identified by a letter indicating the group followed by one or two numbers. 

Wear Resistance (steel wheel passes necessary for 1cm wear) 7700 2400... 

A major application for surface modification is making materials more corrosion and wear resistant. Steel is used in everything from skyscrapers to motorcycles, so increasing the stability of this crucial material is a priority not only for many people in the steel industry but also for industries that use the steel to fabricate other products. 

Embedded in the refractory brickwork are lifters made of heat-resisting and wear-resisting cast steel. Purely chrome-alloy steel grades with about 30% chromium content have been found suitable for the purpose, the more so as they are relatively inexpensive. Ceramic internal fittings are not suitable for rotary coolers. Nor have special lifter bricks proved satisfactory, as their heads spall or wear down too rapidly. Scoops (or flights) made of wear-resisting steel and designed to scatter... 

Cyclone tube construction. In addition to high efficiency and capacity, an ideal cyclone must be constructed to withstand many years of abrasive wear and be rugged enough to withstand the potuiding inherent in compressor station operation. The critical wearing parts of the cyclone tubes are made of a special wear-resistant steel alloyed with nickel and chromimn. This material combines abrasive resistance with toughness or shock-resistant qualities. 

Heightened wear resistance of the pickup working surface thanks to the use of a protective plate of stainless steel. 

Beryllium is added to copper to produce an alloy with greatly increased wear resistance it is used for current-carrying springs and non-sparking safety tools. It is also used as a neutron moderator and reflector in nuclear reactors. Much magnesium is used to prepare light nieial allo>s. other uses include the extraction of titanium (p. 370) and in the removal of oxygen and sulphur from steels calcium finds a similar use. 

Nitriding can impart significant wear resistance to steel surfaces, as illustrated in Eigure 8. The resistance to abrasion of an uncase hardened steel compared to that of the same steel nitrided, and the steel having a carburized case, is shown (3,17). Improvement in weight loss is related direcdy to the hardness of the case. 

Eig. 8. Illustration of the effect of nitriding on the wear resistance of a steel blasted with steel grit A, 300 HV steel B, 750 HV steel case hardened by carburizing and C, 1100 HV steel nitrided at 500°C for 60 h (17). HV = Vickers hardness. 

Ferrophosphoms is produced as a by-product in the electrothermal manufacture of elemental phosphoms, in which iron is present as an impurity in the phosphate rock raw material. The commercial product contains ca 23—29% P and is composed primarily of Fe2P [1310-43-6] and Fe P [12023-53-9] along with impurities such as Cr and V. Ferrophosphoms is used in metallurgical processes for the addition of phosphoms content. Low concentrations (up to - 0.1%) of phosphoms in wrought and cast iron and steel not only increases the strength, hardness, and wear resistance but also improves the flow properties. In large stmctural members and plates, it is desirable to use a type of steel that does not need to be quenched or tempered, and thus does not exhibit weld-hardening. This property is afforded by the incorporation of a small quantity of phosphoms in steel. Ferrophosphoms from western U.S. phosphoms production is used as a raw material for the recovery of vanadium (see Vanadiumand vanadiumalloys). 

The materials used in a total joint replacement ate designed to enable the joint to function normally. The artificial components ate generally composed of a metal piece that fits closely into bone tissue. The metals ate varied and include stainless steel or alloys of cobalt, chrome, and titanium. The plastic material used in implants is a polyethylene that is extremely durable and wear-resistant. Also, a bone cement, a methacrylate, is often used to anchor the artificial joint materials into the bone. Cementiess joint replacements have mote tecentiy been developed. In these replacements, the prosthesis and the bone ate made to fit together without the need for bone cement. The implants ate press-fit into the bone. 

The durabihty and versatility of steel are shown by its wide range of mechanical and physical properties. By the proper choice of carbon content and alloying elements, and by suitable heat treatment, steel can be made so soft and ductile that it can be cold-drawn into complex shapes such as automobile bodies. Conversely, steel can be made extremely hard for wear resistance, or tough enough to withstand enormous loads and shock without deforming or breaking. In addition, some steels are made to resist heat and corrosion by the atmosphere and by a wide variety of chemicals. 

Low—medium alloy steels contain elements such as Mo and Cr for hardenabiHty, and W and Mo for wear resistance (Table 4) (7,16,17) (see Steel). These alloy steels, however, lose their hardness rapidly when heated above 150—340°C (see Fig. 3). Furthermore, because of the low volume fraction of hard, refractory carbide phase present in these alloys, their abrasion resistance is limited. Hence, low—medium alloy steels are used in relatively inexpensive tools for certain low speed cutting appHcations where the heat generated is not high enough to reduce their hardness significantly. 

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