| Abstract: | We determine the magnitude of microstresses and the number of dislocations in sintered steels by x-ray analysis. We have determined that large microstresses are present in the material after sintering, and their magnitude grows with the carbon content in the material. Powder steels contain a large number of random dislocations, the density of which exceeds the dislocation wall density by two or three orders of magnitude. 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 sintering in a furnace, since better mechanical properties are achieved with a shorter tempering. The improvement in properties is achiered due to formation of a considerable amount of martensite phase in the material for a fast cooling rate in electric contact sintering. Large interparticle areas are formed due to a local rise in temperature and liquid formation, and this effect also contributes to the improvement in properties. Institute of the Physics of Metals, National Academy of Sciences of Ukraine, Kiev. Institute of Materials Science, Slovak Academy of Sciences, Kosice, Slovakia. Translated from Poroshkovaya Metallurgiya, Nos. 7-8, pp. 13–21, July–August 1997. |
