Effect of Plating Conditions on Residual Stress and Microstrain of Pulse-Plated Crack-Free Cr Layer

The residual stress and microstrain of crack-free Cr layers deposited by pulse current electrolysis was evaluated by X-Ray diffraction methods. Changing the on-time and off-time periods, various residual stresses were measured. The residual stress was influenced by the off-time period in the same on-time period. In order to obtain Cr layers that have compressive residual stress, a suitable off-time period corresponding to the on-time period should exist. When the off-time period was too short or too long compared to the suitable off-time period, tensile residual stress was generated in the Cr layer. With increasing bath temperature and current density, the residual stress became more compressive. Microstrain decreased at high bath temperatures and low current densities. The amount of change in the residual stress due to heat treatment correlated with the microstrain, and became smaller and more stable with heat treatment as the microstrain decreased. The Vickers hardness of the Cr layer was governed by microstrain; the hardness increases with increasing microstrain.