Abstract
18 Cr-8 Ni stainless steel wires 0.160mm and 0.035mm in diameters were wound in layers on core rods of the same steel. Before sintering in hydrogen, the wire layers were cold-pressed in the direction along core axis to form flat contact areas between wires, with widths of one third of the each original wire diameter. Welds between contacting surfaces of wires were observed on sections of the wire layers by optical and scanning-electron microscopes.
The initial stage of sintering begins by the formation of micro welds at some points between contacting surfaces. The welds grow and coalesce with each other eliminating micro pores between them to occupy whole the flat contacts between wires. The activation energy of welding 60% of the flat area is lower than that for grain boundary diffusion of iron in a stainless steel. The energy of welding 90% is similar to that for volume diffusion. Welding rates during the initial stage of sintering are independent on wire diameter. The growth of a whole neck proceeds more rapidly between smaller wires than between larger ones. Curvatures of the necks are independent on wire diameter.
