Evaluation of indentation induced residual stress in the surface of float glass

Residual stress field around a Vickers diamond indentation was studied usin g float glass as a model specimen. The basis of the experimental technique is to use cracks from a small indentation as a microprobe to measure the re sidual stress at a specific point around a large indentation and to study t he change of the residual stress by heat treatment. Residual tensile and co mpressive stresses around a large indentation produced by applying the load of 19.6 N were distributed up to the distance of about 300 mu m from the i ndentation center. The tensile and compressive stresses were 10 MPa and -40 MPa, respectively, at a distance of 200 mu m from the indentation center, The residual stress decreased by heat treatment and became zero by keeping the indented specimen at 550 degrees C, a temperature which is close to the annealing point of the glass, for 2h. The depth of the indentation also de creased by heat treatment, This technique can be widely applied to study re sidual-stress-related phenomena in ceramics as well as in glass.