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Handbook Properties and Selection Nonferrous Alloys and Spl Purpose Mtls (1992) WW Part 4

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Tham khảo tài liệu 'handbook properties and selection nonferrous alloys and spl purpose mtls (1992) ww part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Table 11 Compositions of typical aluminum P M alloy powders Grade Composition Cu Mg Si Al Lubricant 601AB 0.25 1.0 0.6 bal 1.5 201AB 4.4 0.5 0.8 bal 1.5 602AB . 0.6 0.4 bal 1.5 202AB 4.0 . . bal 1.5 MD-22 2.0 1.0 0.3 bal 1.5 MD-24 4.4 0.5 0.9 bal 1.5 MD-69 0.25 1.0 0.6 bal 1.5 Aluminum P MPart Processing Basic design details for aluminum P M parts involve the same manufacturing operations equipment and tooling that are used for iron copper and other metal-powder compositions. Detailed information on P M design and processing can be found in Powder Metal Technologies and Applications Volume 7 of ASM Handbook. Compacting. Aluminum P M parts are compacted at low pressures and are adaptable to all types of compacting equipment. The pressure density curve which compares the compacting characteristics of aluminum with other metal powders indicates that aluminum is simpler to compact. Figure 11 shows the relative difference in compacting characteristics for aluminum and sponge iron or copper. Fig. 11 Relationship of green density and compacting pressure The lower compacting pressures required for aluminum permit wider use of existing presses. Depending on the press a larger part often can be made by taking advantage of maximum press force. For example a part with a 130 cm2 20 in.2 surface area and 50 mm 2 in. depth is formed readily on a 4450 kN 500 ton press. The same part in iron would require a 5340 kN 600 ton press. In addition because aluminum responds better to compacting and moves more readily in the die more complex shapes having more precise and finer detail can be produced. Sintering. Aluminum P M parts can be sintered in a controlled inert atmosphere or in vacuum. Sintering temperatures are based on alloy composition and generally range from 595 to 625 C 1100 to 1160 F . Sintering time varies from 10 to 30 min. Nitrogen dissociated ammonia hydrogen argon and vacuum have been used for sintering aluminum however nitrogen is preferred because it results in high .