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Steel Heat Treatment - Metallurgy and Technologies 2nd ed - G. Totten (CRC_ 2007) 9

Tham khảo tài liệu 'steel heat treatment - metallurgy and technologies 2nd ed - g. totten (crc_ 2007) 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | to be avoided Figure 7.67 199 . The different nitrocarburizing processes have obviously no effect. As for rolling contact fatigue the acting stress according to Mises criterion reaches its highest value beneath the surface at low-friction coefficients with increasing friction the maximum value shifts toward the surface 200 . Depending on the applied load either case depth or surface condition surface intergranular oxidation porosity must be fixed 201 . A high nitriding case depth which can be produced in the gas nitriding of nitriding steels is advantageous for gears but their case depth should however not exceed 0.2 X modulus to avoid nitriding of the tooth tips that would entail embrittlement 202 . The maximum values that can be reached for the flank load capacity of carburized gears can be reached with case depths in the size range of 0.25 X modulus Figure 7.68 203 . The optimum case depth for the tooth bending fatigue strength which is also shown in Figure 7.68 illustrates that in determining the heat treatment parameters it is necessary to weigh optimal tooth bending fatigue strength against optimal flank load capacity. REFERENCES 1. P.G. Shewmon Metallurgical thermodynamics in Physical Metallurgy R.W. Cahn Ed. 2nd ed. North-Holland Amsterdam 1970 p. 281. 2. M.G. Frohberg Thermodynamik fur Metallurgen und Werkstofftechniker VEB Deutscher Verlag fur Grundstoffindustrie Leipzig 1980. 3. E. Fromm Thermodynamik Springer-Verlag Berlin 1970. 4. Th. Heumann Diffusion in Metallen Springer-Verlag Berlin 1992. 5. P.G. Shewmon Diffusion in Solids 2nd ed. McGraw-Hill New York 1989. 6. G. Horz Kinetik und Mechanismen in Gase und Kohlenstoff in Metallen E. Fromm E. Gebhardt Eds. Springer-Verlag Berlin 1975 p. 84. 7. E. Doehlemeier Z. Elektrochemie 42 561 1936 . 8. JANAF Thermochemical Tables 2nd ed. 1971. 9. J.F. Elliott M. Gleiser Thermochemistry for Steelmaking Addison-Wesley Reading 1960. 10. C. Wagner Z. anorg. Chemie 199 321 1931 . 11. A. Fick Poggendorf Annalen 94 59