Influence of pulsation deformations on properties of steel grade Cr18Ni10

This paper presents initial results of pulsatory forming performed on a pulsator at the Department of Metal Forming, Faculty of Metallurgy, Technical University in Kosice. Pulsatory forming (stress-cycling) is a non-conventional forging method based on application of a variable pulsation frequency during the metal forming process. The pulsation frequency and amplitudes during pulsatory forming are new technological parameters using which we can influence both processes taking place in the formed metal (recrystallization, grain growth, transformation processes) and the contact area between the formed metal and the forming toot (the character of friction and related impacts on the deformation course and the formability). The influence of summary deformation as a function of pulsation frequency and the influence of the geometrical parameter "Theta" on the microstructure (AGS diameter), mechanical properties R-p0,R-2; R-m; A(5); Z and geometry of experimental samples of steel grade Cr18Ni10 were analyzed. At a value of summary deformation of 25 % (at the pulsation frequency of 30 Hz) a very good compromise was achieved between yield strength, tensile strength - elongation and contraction. The maximum value of R-p0,R-2 and R-m was achieved at the geometrical parameter Theta = 20 %. At a value of parameter 0 = 20 % a high value was achieved of plastic properties A(5) and Z (ca 80 %). The value of geometrical parameter Theta of 20 % or the highest value of Theta improved the flow of material at pulsation forming process point of view of the lower of plastic deformation heterogeneity.