Fatigue behavior of binder-treated P/M steels

Nikhilesh Chawla, S. Polasik, K. S. Narasimhan, T. Murphy, M. Koopman, K. K. Chawla

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The microstructure, tensile, and axial fatigue behavior of Fe-Mo-Cu-Ni alloys made by binder-treated processing were investigated and the attendant mechanical behavior compared to that of an analogous alloy processed by diffusion alloying. Binder treatment can provide a variety of advantages in manufacturing over diffusion alloyed powders, including faster and more consistent flow into the die cavity, increased green strength, and reduction of fine particle dusting. In addition to conventional porosity, smaller, "copper diffusion" pores were observed where copper particles were present prior to forming a liquid phase during sintering and diffusion into the iron particles. The heterogeneous microstructure in both alloys was typical of P/M alloy steels, consisting of areas of "divorced pearlite," martensite, and nickel-rich ferrite. Tensile and fatigue resistance were enhanced by an increase in the molybdenum content in the alloys. The tensile strength of both types of alloys was similar and fatigue life was essentially identical for the two systems. Fractographic observations showed that fracture initiated primarily at pore clusters in the surface region. Investigation of small cracks by a surface replication technique showed that fatigue cracks nucleated at pores or pore clusters, and that crack propagation exhibited a significant amount of deflection and branching, attributed to local obstacles in the microstructure, such as Ni-rich areas. Fracture surfaces showed ductile fracture in the interparticle bridge regions, cleavage facets in pearlitic regions, and striations due to cyclic loading.

Original languageEnglish (US)
Pages (from-to)49-57
Number of pages9
JournalInternational Journal of Powder Metallurgy (Princeton, New Jersey)
Volume37
Issue number3
StatePublished - Apr 2001

Fingerprint

Steel
Binders
Fatigue of materials
Microstructure
Copper
Liquid phase sintering
Molybdenum
Ductile fracture
Pearlite
Alloy steel
Nickel
Alloying
Martensite
Powders
Ferrite
Crack propagation
Tensile strength
Iron
Porosity
Cracks

ASJC Scopus subject areas

  • Metals and Alloys

Cite this

Chawla, N., Polasik, S., Narasimhan, K. S., Murphy, T., Koopman, M., & Chawla, K. K. (2001). Fatigue behavior of binder-treated P/M steels. International Journal of Powder Metallurgy (Princeton, New Jersey), 37(3), 49-57.

Fatigue behavior of binder-treated P/M steels. / Chawla, Nikhilesh; Polasik, S.; Narasimhan, K. S.; Murphy, T.; Koopman, M.; Chawla, K. K.

In: International Journal of Powder Metallurgy (Princeton, New Jersey), Vol. 37, No. 3, 04.2001, p. 49-57.

Research output: Contribution to journalArticle

Chawla, N, Polasik, S, Narasimhan, KS, Murphy, T, Koopman, M & Chawla, KK 2001, 'Fatigue behavior of binder-treated P/M steels', International Journal of Powder Metallurgy (Princeton, New Jersey), vol. 37, no. 3, pp. 49-57.
Chawla N, Polasik S, Narasimhan KS, Murphy T, Koopman M, Chawla KK. Fatigue behavior of binder-treated P/M steels. International Journal of Powder Metallurgy (Princeton, New Jersey). 2001 Apr;37(3):49-57.
Chawla, Nikhilesh ; Polasik, S. ; Narasimhan, K. S. ; Murphy, T. ; Koopman, M. ; Chawla, K. K. / Fatigue behavior of binder-treated P/M steels. In: International Journal of Powder Metallurgy (Princeton, New Jersey). 2001 ; Vol. 37, No. 3. pp. 49-57.
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