Transactions of the Indian Institute of Metals

, Volume 71, Issue 12, pp 3037–3043 | Cite as

Effects of Ti and Nb on the Grain Refinement and Mechanical Properties of AISI 4145 Steel

  • Sung-Youl Seo
  • Seok-Jae Lee
Technical Paper


In this study, we investigated the effects of Ti and Nb additions on the grain size of prior austenite and mechanical properties such as yield strength, yield ratio, and impact toughness in quenched and tempered AISI 4145 steel. It was found that the grain size of prior austenite directly influenced the mechanical properties. Thermodynamic calculations were carried out to find the characteristics of the precipitates such as dissolution temperature of precipitates, the average size of precipitate particles, precipitate fraction, and mean distance among precipitate particles, quantitatively. A specimen with low Ti content had a smaller Ti/N ratio than the stoichiometric ratio of 3.42 and showed an effective inhibition of grain growth of prior austenite, whereas a specimen with high Ti content showed a little effect to prevent the austenite grain growth compared with a Ti-free sample. Based on the thermodynamic simulation, the (Nb, Ti) (C, N) complex was precipitated and contributed to the inhibition of austenite grain growth, resulting in not only higher yield strength and yield strength/tensile strength ratio but also improved toughness.


Microalloying Grain refinement Strength Impact toughness AISI 4145 


  1. 1.
    Senuma T, ISIJ Inter 41 (2011) 520.CrossRefGoogle Scholar
  2. 2.
    Lai G Y, Wood W E, Clark R A, Zackay V F, and Parker E R, Metall Trans 5 (1974) 1663.CrossRefGoogle Scholar
  3. 3.
    Ritchie R, Francis B, and Server W L, Metall Trans A 7 (1976) 831.CrossRefGoogle Scholar
  4. 4.
    Ritchie R O, and Horn R M, Metall Trans A 9 (1978) 331.CrossRefGoogle Scholar
  5. 5.
    Tomita Y, and Okabayashi K, Metall Trans A 14 (1983) 485.CrossRefGoogle Scholar
  6. 6.
    Tomita Y, and Okabayashi K, Metall Trans A 16 (1985) 73.CrossRefGoogle Scholar
  7. 7.
    Tomita Y, Metall Trans A 18 (1987) 1495.CrossRefGoogle Scholar
  8. 8.
    Leap M J, and Wingert J C, Metall Mater Trans A 30 (1999) 93.CrossRefGoogle Scholar
  9. 9.
    Nedjada S H, Teimouri J, Tahmasebifar A, Shirazi H, and Ahmadabadi M N, Scr Mater 60 (2009) 528.CrossRefGoogle Scholar
  10. 10.
    Millán J, Sandlöbes S, Al-Zubi A, Hickel T, Choi P, Neugebauer J, Ponge D, and Raabe D, Acta Mater 76 (2014) 94.CrossRefGoogle Scholar
  11. 11.
    Zargari H H, and Nedjad H, J Mater Eng Perform 24 (2015) 3453.CrossRefGoogle Scholar
  12. 12.
    Choi J Y, Ji J H, Hwang S W, and Park K T, Mater Sci Eng A 535 (2012) 32.CrossRefGoogle Scholar
  13. 13.
    Behjati P, Kermanpur A, Najafizadeh A, and Samaei Baghbadorani H, Mater Sci Eng A 592 (2014) 77.CrossRefGoogle Scholar
  14. 14.
    Behjati P, Kermanpur A, Najafizadeh A, Samaei Baghbadorani H, Karjalainen L P, Jung J G, and Lee Y K, Mater Des 63 (2014) 500.CrossRefGoogle Scholar
  15. 15.
    Kang Y, Yu H, Fu J, Wang K, and Wang Z, Mater Sci Eng A 351 (2003) 265.CrossRefGoogle Scholar
  16. 16.
    Militzer M, Giumelli A, Hawbolt E B, and Meadowcroft T R, Metall Mater Trans A 27 (1996) 2299.Google Scholar
  17. 17.
    Gao N, and Baker T N, ISIJ Inter 38 (1998) 744.CrossRefGoogle Scholar
  18. 18.
    Kundu A, ISIJ Inter 54 (2014) 677.CrossRefGoogle Scholar
  19. 19.
    Cuddy L J, and Raley J C, Metall Trans A 14 (1983) 1989.CrossRefGoogle Scholar
  20. 20.
    Medina S F, Chapa M, Valles P, Quispe A, and Vega M I, ISIJ Inter 39 (1999) 930.CrossRefGoogle Scholar
  21. 21.
    Wang S C, J Mater Sci 24 (1989) 105.CrossRefGoogle Scholar
  22. 22.
    Wang S C, Mater Sci Eng A 145 (1991) 87.CrossRefGoogle Scholar
  23. 23.
    Inoue K, Ohnuma I, Ohtani H, Ishida K, and Nishizawa T, ISIJ Inter 38 (1998) 991.CrossRefGoogle Scholar
  24. 24.
    Medina S F, Vega M I, Gómez M, and Gómes P P, ISIJ Inter 45 (2005) 1307.CrossRefGoogle Scholar
  25. 25.
    MatCalc software. Available online:
  26. 26.
    Chapa M, Medina S F, López V, and Fernández B, ISIJ Inter 42 (2002) 1288.CrossRefGoogle Scholar
  27. 27.
    Balasubramanian K, Kroupa A, and Kirkaldy J S, Metall Trans A 23 (1992) 709.CrossRefGoogle Scholar
  28. 28.
    Armstrong R W, Metall Trans 1 (1970) 1169.CrossRefGoogle Scholar
  29. 29.
    Hansen N, Scr Mater 51 (2004) 801.CrossRefGoogle Scholar
  30. 30.
    Lee S, Estrin Y, and De Cooman B C, Metall Mater Trans A 44 (2013) 3136.CrossRefGoogle Scholar
  31. 31.
    Ardell A J, Metall Mater Trans A 16 (1985) 2131.CrossRefGoogle Scholar
  32. 32.
    Cao W D, and Lu X P, Metall Trans A 18 (1987) 1569.CrossRefGoogle Scholar
  33. 33.
    Yan W, Shan Y Y, and Yang K, Metall Mater Trans A 37 (2006) 2147.CrossRefGoogle Scholar

Copyright information

© The Indian Institute of Metals - IIM 2018

Authors and Affiliations

  1. 1.Product Research Center, R&D CenterSeAH BesteelSoryong-dong, GunsanKorea
  2. 2.Division of Advanced Materials Engineering, Research Center for Advanced Materials DevelopmentChonbuk National UniversityJeonjuKorea

Personalised recommendations