Many loading situations induce stresses which peak at or slightly beneath the surface of a component and thus require improved strength and wear resistance in those areas. This has triggered research how to reinforce porous P/M components precisely in the highly loaded regions. It has been demonstrated that selective surface densification (SSD) can produce a surface layer close to full density, which typically ranges to a depth between 0.5 and 1 mm.

Most crucial for the efficiency of SSD is to which extent porosity has been removed. The present work describes a methodology how to prepare and characterize densified surfaces by metallography and subsequent quantitative image analysis. Specifically, the volume fraction, size, shape and orientation of pores in the densified layer are assessed as a function of distance from the surface and compared to the uncompacted condition. It is shown that the current rolling process generates a density gradient ranging from nearly full density at the surface down to the core porosity across a distance of ˜ 1 mm. The mean pore size at the surface is reduced to ˜ 60% of the pore size in the core. Furthermore, the densification process generates nearly spherical pores in the densified zone, whereas the pores in the core remain slightly elongated. Finally, a homogeneous orientation of the pores with no differences between the core and the densified zone is observed.