INFLUENCE OF STRAIN RATE ON PLASTIC DEFORMATION HETEROGENEITY OF MICROALLOYED STEEL FOR COLD FORMING
Abstract
The paper analyses the effect of strain rate on plastic deformation heterogeneity of the two microalloyed steels S 315 MC and S 460 MC, pre-determined for cold work, subjected to uniaxial loading. The plastic deformation development has been analysed on the specimen surface with respect to macro and micro searching considering different sealing area of analysis. The two strain rates of ? = 10-4s-1 and = 102 s-1 respectively, representing static and dynamic loading which have been applied. The mean range of deformation 5 to 35% of ran corresponding to each individual deformation step resulted in distance graduation change. To evaluate the heterogeneity of plastic deformation the values L and were used.
The results confirm that deformation heterogeneity distribution increases with increasing value of the mean deformation applied, as for macro and as for micro view. In conformity with references the plastic deformation heterogeneity decreased as grain size was finer. The average ferrite grain size of experimental steels is finer (~0.009mm and 0.006mm respectively) than for carbon steels used for cold deformation and demonstrate (exhibit) expressively lower plastic deformation heterogeneity. The applied strain rate showed practically no influence on deformation heterogeneity for tested steels. Considering a general trend in order to increase productivity rate simply only by forming rate increasing this fact should be considered of great importance.
Keywords: microalloyed steel|deformation rate|heterogeneity of plastic deformation|
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