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Journal of Heat Treating

, Volume 2, Issue 1, pp 3–19 | Cite as

A study of reactions occurring during the carbonitriding process

  • J. Slycke
  • T. Ericsson
Article

Abstract

The reactions occurring during the carbonitriding process have been studied theoretically and experimentally. A model for the prediction of the amount of residual ammonia in the furnace from the process parameters, temperature, inlet gas composition and flow-rate is presented. It takes account of ammonia decomposition and formation of the hydrogen cyanide. The ammonia addition and decomposition also cause a dilution of the carburizing atmosphere resulting in a shift in the gas equilibria and the carbon potential. A method to take this into account is presented. The examination of the formation of hydrogen cyanide and its behaviour in the atmosphere leads to the conclusion that hydrogen cyanide is of major importance as a nitriding component. All carburizing and nit riding reactions are listed together with equilibrium and rate constants.

Keywords

Austenite Carbon Potential Hydrogen Cyanide Furnace Wall Nitrogen Activity 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notation

Symbols

A

area [m2]

Ai

preexponential factor [m2/s]

C

constant

Cpot

carbon potential [pct by weight]

Di

diffusion coefficient [m2/s]

E

activation energy [J/mol]

Ey

Young’s modulus [N/m2]

Fd

dilution factor

ΔGi

(activation) free energy [J/mol]

ΔHi

(activation) enthalpy [J/mol]

Ji

specific mass flow [mol/(m2/s)]

Ki

adsorption coefficient

Kn

equilibrium constant

K1i…K4j

interaction energies [J/mol]

Mi

molar weight

Npot

nitrogen potential [pct by weight]

Pa

ambient pressure

Pt

probability factor

Q0

carrier gas flow rate [m3/s]

Q1

entering gas flow rate [m3/s]

Q2

exhaust gas flow rate [m3/s]

R

gas constant [J/(mol K)] or [m3 atm/(mol K)]

ΔSi

activation entropy [J/(mol K)]

T

temperature [K]

V

volume [m3]

Vm

molar volume [m3/mol]

ΔVi

activation volume [m3/mol]

a

lattice parameter [m] or [Å]

ai

activity ofi

ci

concentration [mol/m3]

oci

concentration proportional to the activity value (Henry’s law) [mol/m3]

dt

total diffusion depth [m]

eik

interaction parameter with regard to wt pct [pct-1]

f

fraction

fi

activity coefficient with regard to wt pct [pct-1]

fn

environmental factor

(pcti)

concentration [pct by weight]

k

the Boltzmann factor [J/K]

kn

forward reaction rate coefficient

kn

backward reaction rate coefficient with regard to concentration

kn

backward reaction rate coefficient with regard to activity

l

2l = void spacing [m]

n

number of moles [mol]

pi

partial pressure [atm]

P′NH3

partial pressure for ammonia in entering gas mixture [atm]

r

radius [m]

snγ/α

catalytic factor

t

time [s]

tn

nucleation time [s]

νn

net reaction rate [mol/(m2 s)]

\(\overrightarrow \upsilon _n \)

forward reaction rate [mol/(m2 s)]

\(\overleftarrow \upsilon \)

backward reaction rate [mol/(m2 s)]

χ

radial coordinate [m]

χi

concentration, mole fraction

yi

concentration, related to mole fraction

α

2α = opening angle of void in grain boundary [deg]

γi

activity coefficient with regard to mole fraction σ width of grain boundary [m]

i

strain around interstitially dissolved atom

ik

interaction parameter with regard to mole fraction

κ

geometric constant

μi

chemical potential [J/mol]

ν

constant

ρ

number of nuclei/growing voids [m-2]

ρi

density [kg/m3]

δ

surface energy [J/m2]

Ω

atomic volume [m3]

Subscripts

A

area

a

ambient conditions

b

grain boundary

c

critical state

f

fraction

i

denotes chemical substance

j

denotes chemical substance

m

denotes molar quantity

max

denotes upper limit

n

reaction number (refers to Appendix A.1 and Table III)

o

reference state

V

volume

Superscripts

b

grain boundary

eq

equilibrium state

f

furnace

gr

graphite

i

denotes chemical substance

j

denotes chemical substance

k

denotes chemical substance

o

reference state

st

standard state

α

ferrite

γ

austenite

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References

  1. 1.
    B. Prenosil:Härt.-Tech. Mitt., 1966, vol. 21, pp. 24–33.Google Scholar
  2. 2.
    B. Prenosil:Härt.-Tech. Mitt., 1966, vol. 21, pp. 124–37.Google Scholar
  3. 3.
    T. Holm:Proc. Conf. Heat Treatment ’73, London 12–13 Dec 1973, The Metals Society Book No 163, pp. 125–128.Google Scholar
  4. 4.
    R. Davies and C. G. Smith:Heat Treat. Met., 1978, vol. 5, pp. 3–10.Google Scholar
  5. 5.
    B. Champin, L. Seraphin, and R. Tricot:Aciers Spec., 1975, vol. 32, pp. 5–13.Google Scholar
  6. 6.
    J. Slycke: Dissertation No. 37, Linköping Studies in Science and Technology, 1979.Google Scholar
  7. 7.
    J. Pomey:Rev. Met., 1950, vol. XLVII, pp. 637–57.Google Scholar
  8. 8.
    J. Pomey:Rev. Met., 1950, vol. XLVII, pp. 727–38.Google Scholar
  9. 9.
    J. Pomey:Härt-Tech. Mitt., 1963, vol. 18, pp. 127–42.Google Scholar
  10. 10.
    B. Prenosil:Härt.-Tech. Mitt., 1964, vol. 19, pp. 31–35.Google Scholar
  11. 11.
    R. Chatterjee-Fischer and O. Schaaber:Härt.-Tech. Mitt., 1969, vol. 24, pp. 121–24.Google Scholar
  12. 12.
    R. Chatterjee-Fischer and O. Schaaber:Härt.-Tech. Mitt., 1969, vol. 24, pp. 292–95.Google Scholar
  13. 13.
    R. Chatterjee-Fischer and O. Schaaber:Härt.-Tech. Mitt., 1971, vol. 26, pp. 108–110.Google Scholar
  14. 14.
    L. Salonen and M. Sulonen:Härt.-Tech. Mitt., 1970, vol. 25, pp. 161–64.Google Scholar
  15. 15.
    J. M. Bello, F. Medina, and B. J. Fernandez:Rev. Metal., 1971, vol. 7, pp. 99–104.Google Scholar
  16. 16.
    F. Medina, J. M. Bello, and B. J. Fernandez:Rev. Metal., 1971, vol. 7, pp. 369–373.Google Scholar
  17. 17.
    B. J. Fernandez, F. Medina, and J. M. Bello:Rev. Metal., 1973, vol. 9, pp. 181–92.Google Scholar
  18. 18.
    J. M. Bello, B. J. Fernandez, and F. Medina:Tech. Met., 1974, vol. 29, pp. 73–82.Google Scholar
  19. 19.
    J. M. Bello, F. Medina, and B. J. Fernandez:Rev. Metal., 1975, vol. 11, pp. 248–58.Google Scholar
  20. 20.
    H. Kurabe:Tetsu to Hagane, 1973, vol. 59, pp. 1251–60,Trans. Iron Steel Inst. Jpn., 1974, vol. 14, pp. 404–10.Google Scholar
  21. 21.
    S. A. Skotnikov, D. Z. Ryabvna, and O. A. Bannykh:Met. Sci. Heat Treat., 1974, vol. 16, pp. 165–66.CrossRefGoogle Scholar
  22. 22.
    Report no. 76634, Institutet för verkstadsteknisk Forskning, Gothenburg, Sweden, 1975.Google Scholar
  23. 23.
    V. P. Akhantev, V. I. Ivlev, and V. P. Kurbatov:Met. Sci. Heat Treat., 1977, pp. 12–15.Google Scholar
  24. 24.
    B. Prenosil:Nitrocementace, SNTL, Prague, 1964.Google Scholar
  25. 25.
    Metals Handbook, 8th Edition, vol. 2, ASM, Metals Park, OH, 1964.Google Scholar
  26. 26.
    Carburizing and Carbonitriding, ASM, Metals Park, OH, 1977.Google Scholar
  27. 27.
    K.-E. Thelning:Steel and its Heat Treatment, Bofors Handbok, Butterworths, London, 1975.Google Scholar
  28. 28.
    H. J. Grabke:Ber. Bunsenges, 1968, vol. 72, pp. 533–41.Google Scholar
  29. 29.
    H. J. Grabke:Ber. Bunsenges., 1968, vol. 72, pp. 541–48.Google Scholar
  30. 30.
    H. J. Grabke:Arch. Eisenhuttenwes., 1975, vol. 46, pp. 75–81.Google Scholar
  31. 31.
    R. Collin, S. Gunnarson, and D. Thulin:J. Iron Steel Inst., 1972, vol. 210, pp. 777–84.Google Scholar
  32. 32.
    H. J. Grabke:Arch. Eisenhuttenwes., 1975, vol. 46, pp. 215–22.Google Scholar
  33. 33.
    J. Slycke:Proc. 16th Intern. Heat Treat. Conf, “Heat Treatment ’76,” Stratford-upon-Avon 6–7 May 1976, The Metals Society, London.Google Scholar
  34. 34.
    A. Bramley and G. Turner:Iron Steel Inst. Carnegie School. Mem., 1928, vol. 17, pp. 23–66.Google Scholar
  35. 35.
    A. Bramley and Heywood:Iron Steel Inst. Carnegie Schol. Mem., 1928, vol. 17, pp. 67–87.Google Scholar
  36. 36.
    F. K. Naumann and G. Langenschied:Arch Eisenhuttenwes, 1965, vol. 36, pp. 583–90.Google Scholar
  37. 37.
    Z. Kolozsvary, V. Sandor, and P. Teszler:Härt.-Tech. Mitt., 1973, vol. 28, pp. 12–17.Google Scholar
  38. 38.
    B. Champin, L. Seraphin, and R. Tricot:Aciers Spec., 1975, vol. 32, pp. 5–13.Google Scholar
  39. 39.
    H. J. Grabke:Arch. Eisenhuttenwes., 1973, vol. 72, pp. 603–08.Google Scholar
  40. 40.
    H. J. Grabke:Ber. Bunsenges, Phys. Chem., 1965, vol. 69, pp. 409–14.Google Scholar
  41. 41.
    H. J. Grabke:Metall. Trans., 1970, vol. 1, pp. 2972–75.Google Scholar
  42. 42.
    H. J. Grabke:Proc. 3rd Intern. Congr. Catalysis North Holland Publ., Amsterdam, 1965, pp. 928–38.Google Scholar
  43. 43.
    H. J. Grabke:Ber. Bunsenges. Phys. Chem., 1967, vol. 71, pp. 1067–73.Google Scholar
  44. 44.
    H. J. Grabke and G. Tauber:Arch. Eisenhuttenwes., 1975, vol. 46, pp. 215–22.Google Scholar
  45. 45.
    H. J. Grabke:Scr. Metall., 1974, vol. 22, pp. 293–95.Google Scholar
  46. 46.
    G. Hägg:Allmän och oorganisk kemi, Almqvist & Wiksell, Uppsala, 1966, 4th edition.Google Scholar
  47. 47.
    L. Darken and R. Gurry:Physical Chemistry of Metals, McGraw-Hill Book Co, New York, 1953.Google Scholar
  48. 48.
    P. Grieveson and E. T. Turkdogan:Trans. Met. Soc. AIME, 1964, vol. 230, pp. 407–14.Google Scholar
  49. 49.
    E. T. Turkdogan and P. Grieveson:J. Electrochem. Soc., 1967, vol. 114, pp. 59–64.CrossRefGoogle Scholar

Copyright information

© American Society for Metals 1981

Authors and Affiliations

  • J. Slycke
    • 1
  • T. Ericsson
    • 2
  1. 1.Materials LaboratoryAtlas Copco MCT ABStockholmSweden
  2. 2.Department of Mechanical Engineering, Institute of TechnologyLincöping UniversityLinköpingSweden

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