THE EFFECT OF ELECTROLYTE-PLASMA TREATMENT IN THE PROCESS OF DEFORMATIVE HARDENING BY DRAWING ON STRENGTH PROPERTIES OF STEEL 12Х18Н9

Abstract

The effect of electrolyte-plasma treatment in the process of deformative hardening by drawing of steel 12Х18Н9 widely used for medical tools and implants manufacturing was investigated. The basic drawing sequence which consists of seven passes and provides the total reduction ratio of 80 % was used. The duration of the intermediate electrolyte-plasma treatment between passes of drawing was from 1 to 10 min. The studies found that the use of electrolytic-plasma treatment between passes of drawing leads to a decrease in the tensile residual stresses in the surface layer. The optimal duration of the intermediate electrolyte-plasma treatment, providing a combination of high tensile strength and low residual stresses, was determined. It is established that the use of an intermediate electrolyte-plasma treatment in the process of deformative hardening by drawing enhances the fatigue strength of the material by reducing the residual stress, dislocation density, the number of defects and foreign inclusions.