Effect of Cr Electroplating Layer Thickness on the Tensile and High Cycle Fatigue Properties of AISI 1045 Steel

초록

This study investigated and compared the tensile and high-cycle fatigue properties of AISI 1045 steel and Cr electroplated AISI 1045 steel. First, tensile and fatigue specimens were machined from AISI 1045 steel (substrate), and two kinds of Cr electroplating layers with different layer thickness were applied. The substrate, AISI 1045 steel consisted of an a-Fe matrix and pearlite, and the two Cr electroplating layers were measured to have thicknesses of 13.1 mu m and 53.9 mu m, respectively. The Cr layer did not show signs of peeling from the substrate, but initial micro cracks were present within the Cr electroplating layer. Tensile test results confirmed that the Cr electroplated specimens had similar yield strengths and tensile strengths to those of the substrate AISI 1045 steel, but elongation decreased significantly. High cycle fatigue results confirmed that the fatigue limit (similar to 10(7) cycles to fatigue failure) of the substrate steel was 600 MPa, and the fatigue limit decreased significantly to 500 MPa (13.1 mu m thickness) and 325 MPa (53.9 mu m thickness) as the Cr electroplating layers were formed. This study also observed fracture surfaces of tensile and high cycle fatigue fractured specimens, and the deformation mechanisms of the Cr electroplated steel were suggested in connection with microstructures.

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