The effect of grain size on the strain hardening coefficient on metalic materials

In this study, the effect of grain size on the strain hardening coefficient has been investigated using SAE/AISI 1020 low carbon unalloyed structural steel and SAE/AISI 8620 low carbon alloyed case hardening steel. Steels used has been annealed on the austenite region of iron-cementite diagram on three different temperatures over A3 temperature. The grain sizes of steels have been increased by increase of annealing temperatures. The grain sizes have been determined using optical microscope. Decrease in the mechanical properties as yield stress, tensile stress has been observed by increase of grain sizes. Uniaxial tension test has been performed on samples which are prepared from steels in order to determine strain hardening coefficient of steels. Strain hardening coefficient have been determined for each sample from obtained stress-strain diagrams. Increase in strain hardening coefficient has been observed by increase of grain sizes in view of grain sizes and strain hardening coefficients.