Axial fatique behavior of binder-treated versus diffusion alloyed powder metallurgy steels

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

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

A comparative study has been conducted on the microstructure, tensile, and axial fatigue behavior of two Fe-0.5Mo-1.5Cu-1.75Ni alloys, made by binder-treated and diffusion alloying processes. The mechanical properties will be explained in terms of the pore size and morphology, as well as the heterogeneous microstructures typical of ferrous powder metallurgy materials. 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 had been prior to forming a liquid phase during sintering and diffusing into the Fe particles. The microstructure in both alloys was typical of P/M alloy steels, with a heterogeneous microstructure consisting of areas of "divorced pearlite," martensite, and nickel-rich ferrite. The modulus and tensile strength of both types of alloys were equivalent. Yield strength in the binder-treated alloy was higher which coincided with somewhat lower ductility. The fatigue behavior in terms of stress versus cycles (S-N curves) was almost identical for the two systems. Fractographic observations showed fracture to have initiated primarily at pore clusters in the surface region. Fracture surfaces after fatigue tests showed ductile fracture in the interparticle bridge regions, cleavage facets in pearlitic regions, and striations.

Original languageEnglish (US)
Pages (from-to)180-188
Number of pages9
JournalMaterials Science and Engineering A
Volume308
Issue number1-2
DOIs
StatePublished - Jun 30 2001
Externally publishedYes

Fingerprint

Steel powder metallurgy
powder metallurgy
Binders
steels
Microstructure
Fatigue of materials
porosity
microstructure
Copper
Liquid phase sintering
stress cycles
Ductile fracture
Pearlite
Alloy steel
Powder metallurgy
liquid phase sintering
pearlite
copper
Nickel
Alloying

Keywords

  • Binder-treatment
  • Fatigue
  • Powder metallurgy
  • Steels

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Axial fatique behavior of binder-treated versus diffusion alloyed powder metallurgy steels. / Chawla, Nikhilesh; Murphy, T. F.; Narasimhan, K. S.; Koopman, M.; Chawla, K. K.

In: Materials Science and Engineering A, Vol. 308, No. 1-2, 30.06.2001, p. 180-188.

Research output: Contribution to journalArticle

Chawla, Nikhilesh ; Murphy, T. F. ; Narasimhan, K. S. ; Koopman, M. ; Chawla, K. K. / Axial fatique behavior of binder-treated versus diffusion alloyed powder metallurgy steels. In: Materials Science and Engineering A. 2001 ; Vol. 308, No. 1-2. pp. 180-188.
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