Effect of Copper Infiltration on Fracture Mode in Sintered Steels Articles uri icon

publication date

  • June 2008

start page

  • 176

end page

  • 181

issue

  • 2

volume

  • 51

international standard serial number (ISSN)

  • 0032-5899

electronic international standard serial number (EISSN)

  • 1743-2901

abstract

  • The fracture mode of PM steels depends on features, such as pores, densification, diffusion of any added alloying elements, contact area between particles, microstructural homogeneity, and applied load conditions. Consequently, when a sintered steel is infiltrated, several factors that determine the fracture behaviour are affected. The density is raised (in absolute terms, because the infiltrant is usually of higher density, and in relative terms, because activated sintering is promoted by permanent liquid phase sintering). The liquid phase promotes a rounding of the pores which enhances stress transmission from the necks to the particles. Sintered steel with 0·6%C was infiltrated with three amounts of copper to study the influences of the amount of infiltration and the resultant final density on the fracture mode. Specimens were first uniaxially pressed to 730 g cm-3 green density, then sintered and infiltrated simultaneously at 1120°C in a 90N2-10H2 atmosphere. The mechanical results and microstructures were analysed to evaluate the fracture behaviour and fracture surfaces. The mechanical behaviour was characterised by hardness, tensile and three point bending tests.