CHARACTERISTICS OF THE VARIATION IN STRUCTURAL DEFECTS AND PROPERTIESOF IRON-BASED POWDER ALLOYS UNDER THE INFLUENCE OF HIGH-SPEED ELECTRIC-HEATING

We determine the magnitude of microstresses and the number of dislocat ions in sintered steels by x-ray analysis. We have determined that lar ge microstresses are present in the material after sintering, and thei r magnitude grows with the carbon content in the material. Powder stee ls contain a large number of random dislocations, the density of which exceeds the dislocation wall density by two or three orders of magnit ide. The presence of random dislocations has a positive effect on the mechanical properties and strength characteristics of sintered carbon steels. Sintering with electric current is better than conventional si ntering in a furnace, since better mechanical properties ate achieved with a shorter tempering, The improvement in properties is achieved du e to formation of a considerable amount of martensite phase in the mat erial for a fast cooling rate in electric contact sintering. Large int erparticle areas are for a due to a local rise in temperature and liqu id formation, and this effect also contributes to the improvement in p roperties.