THE BAUSCHINGER EFFECT IN SINTERED STEELS

Tension-compression and four-point bending tests were carried out usin g sintered Fe, Fe-Cy Fe-P and Fe-C-Cu alloys to characterize the Bausc hinger effect in porous materials. The greater the level of porosity t he stronger the Bauschinger effect. Porosity in sintered materials con tributes to the Bauschinger effect in two ways: first, pores act as lo cal stress concentrators and after the external load is released they result in heterogeneous plastic strain and residual stresses; second, pores which act differently under tension and compression lead to a vo lume change during plastic strain. The Bauschinger effect is stronger under forward tensile stress than under compressive stress, and is als o larger in tension-compression than in four-point bending.