Alloy steels, 290 table

Soft magnetic materials are characterized by high permeabiUty and low coercivity. There are sis principal groups of commercially important soft magnetic materials iron and low carbon steels, iron—siUcon alloys, iron—aluminum and iron—aluminum—silicon alloys, nickel—iron alloys, iron-cobalt alloys, and ferrites. In addition, iron-boron-based amorphous soft magnetic alloys are commercially available. Some have properties similar to the best grades of the permalloys whereas others exhibit core losses substantially below those of the oriented siUcon steels. Table 1 summarizes the properties of some of these materials. 

Table 3. Standard Numerical AISI-SAE Designations of Plain Carbon and Constructional Alloy Steels...

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. 

Table 4. Compositions of Carbon and Low-Medium Alloy Steels, Wt...

Table 18. Basic Numbering System for Chromium-Bearing Low Alloy Steels...

Subsection C This subsection contains requirements pertaining to classes of materials. Carbon and low-alloy steels are governed by Part UCS, nonferrous materials by Part UNF, high-alloy steels by Part UHA, and steels with tensile properties enhanced by heat treatment by Part UHT. Each of these parts includes tables of maximum allowable stress values for all code materials for a range of metal temperatures. These stress values include appropriate safety fac tors. Rules governing the apphcation, fabrication, and heat treatment of the vessels are included in each part. 

Vessels for high-temperature serviee may be beyond the temperature hmits of the stress tables in the ASME Codes. Sec tion TII, Division 1, makes provision for construction of pressure vessels up to 650°C (1200°F) for carbon and low-alloy steel and up to 815°C (1500°F) for stainless steels (300 series). If a vessel is required for temperatures above these values and above 103 kPa (15 Ibf/in"), it would be necessaiy, in a code state, to get permission from the state authorities to build it as a special project. Above 815°C (1500°F), even the 300 series stainless steels are weak, and creep rates increase rapidly. If the metal which resists the pressure operates at these temperatures, the vessel pressure and size will be limited. The vessel must also be expendable because its life will be short. Long exposure to high temperature may cause the metal to deteriorate and become brittle. Sometimes, however, economics favor this type of operation. 

Carbon steel and alloy combinations appear in Table 11-12 Alloys in chemical- and petrochemical-plant sei vice in approximate order of use are stainless-steel series 300, nickel. Monel, copper alloy, aluminum, Inconel, stainless-steel series 400, and other alloys. In petroleum-refinery sei vice the frequency order shifts, with copper alloy (for water-cooled units) in first place and low-alloy steel in second place. In some segments of the petroleum industiy copper alloy, stainless series 400, low-alloy steel, and aluminum are becoming the most commonly used alloys. 

Silica and Feldspar These are ground in silex-lined mills with flint balls (see Table 20-28). At a mine near Cairo, Illinois, silica is successfully crushed prior to ball-milling in American rotaiy impact mills having loose crushing rings made of hard alloy steel. The rings are easily replaced as they wear. 

Estimation of corrosion likelihood results from consideration of the characteristics of the soils and of the installed object, which are tabulated in Table 4-1 for nonalloyed and low-alloy steel products. Rating numbers, Z, are given according to the data on individual characteristics from which a further judgment can be made using the sum of the rating numbers. 

Table 16-2 Protection potential regions for plain carbon and low-alloy steels (YP 800 N mm ) for marine structures...

Table 4-15 lists base materials Elliott has tested. This list, which is continually being expanded, includes low alloy steels, high alloy iron base, nickel base, cobalt base materials, and odiers. Table 4-16 shows some of the coatings Elliott has tested. The list indicates die supplier, coating designation, and major components of the coating composition. 

Low-carbon, low-alloy steels are in widespread use for fabrication-welded and forged-pressure vessels. The carbon content of these steels is usually below 0.2%, and the alloying elements that do not exceed 12% are nickel, chromium, molybdenum, vanadium, boron and copper. The principal applications of these steels are given in Table 3.8. 

Table 3.8. Applications of Low-Carbon, Loiw-Alloy Steels [10]...

Plain tubes (either as solid wall or duplex) are available in carbon steel, carbon alloy steels, stainless steels, copper, brass and alloys, cupro-nickel, nickel, monel, tantalum, carbon, glass, and other special materials. Usually there is no great problem in selecting an available tube material. However, when its assembly into the tubesheet along with the resulting fabrication problems are considered, the selection of the tube alone is only part of a coordinated design. Plain-tube mechanical data and dimensions are given in Tables 10-3 and 10-4. 

All ordinary ferrous structural materials, mild steels, low-alloy steels and wrought irons corrode at virtually the same rate when totally immersed in natural waters. Wrought iron may be slightly more resistant than mild steel in a test in sea-water at Gosport, Scottish wrought-iron specimens lost about 15% less weight after 12 months immersion than specimens of ordinary mild steel. As shown in Table 3.5, the process of manufacture and the composition of mild steel do not affect its corrosion rate appreciably . 

When low-alloy steels are exposed outdoors, the rust formed on them is generally darker in colour and much finer in grain than that formed on ordinary steel. Moreover, the slowing down in rusting rate with time (cf. Section 3.1, p. 3 13) seems to be more marked for low-alloy steels than for ordinary steels. This can be illustrated by the BISRA figures given in Table 3.8. 

From a consideration of Table 3.10, a copper-phosphorus steel might be chosen for its resistance to corrosion in the critical tidal and splash zone. However, the variation of corrosion resistance is much greater than the difference between various alloy steels so it is improbable that low-alloy steels will corrode more slowly than mild steel in most practical environments. This conclusion is supported by Forgeson etal. who concluded from extensive tests in fresh and salt waters of the Panama Canal Zone that Proprietary low-alloy steels were not in general more resistant to underwater corrosion than the mild unalloyed carbon steel . ... 

The average rates of corrosion of Fe-36Ni alloy exposed to alternate immersion in sea-water are appreciably greater than those that occur when the alloy is exposed to marine atmospheres. Although the rates of corrosion are significantly below those observed for mild steel (Table 3.32) the superiority over mild steel in not so great with respect to pitting attack. 

Table 7.6 Effect of various gases on the oxidation of metals and alloy steels (gains in gm d )...

Rohrig, van Duzer and Fellows exposed samples in an experimental superheater fed with steam at 2-6MN/m from a power plant. Some 42 materials were tested for periods of up to 16(XX)h, attack being estimated after test by weight loss following descaling. It was concluded that at 593°C attack continues at a high rate on carbon steel, whereas the rate for most alloy steels decreases with time (Table 7.10). 

His calculated cost ratings, relative to the rating for mild steel (low carbon), are shown in Table 7.6. Materials with a relatively high design stress, such as stainless and low alloy steels, can be used more efficiently than carbon steel. 

Minimum Energy Requirements. Except for bolting materials, the applicable minimum energy requirements for carbon and low alloy steels with specified minimum tensile strengths less than 656 MPa (95 ksi) shall be those shown in Table GR-2.1.3(e). 

Table PL-2.5.2 Thermal Expansion of Carbon and Low Alloy Steel...

Table IX-5C Low and Intermediate Alloy Steels Performance Factor, Mf...

Steel and alloy steel horizontal pumps, and their baseplates, and vertically suspended pumps shall be designed for satisfactory performance when subjected to the forces and moments in Table 2-1A (2-IB). For horizontal pumps, two effects of nozzle loads are considered Distortion of the pump casing (see 2.2.8) and misalignment of the pump and driver shafts (see 3.3.5). 

For pump casings constmcted of materials other than steel or alloy steel or for pumps with nozzles larger than 16 NPS, the vendor shall submit allowable nozzle loads corresponding to the format in Table 2-lA (2-IB). 

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