Reduction of residual stresses in mandrelled thick-walled cylinders

The methodology and results of experimental studies on possibility to reduce residual stresses in the mandrelled cylinders of steel grade 45 (0.45% C) with 5 mm diameter hole and with a wall thickness ratios 2 and 3 by plastic tension are presented in the article. It is found that even when the axial tensile plastic deformation is 0.005 significant decrease in the district of residual stresses in these cylinders occurs; with deformation increasing up to 0.015…0.020 county residual stresses are reduced in magnitude from 140…500 MPa to 30 ... 50 MPa. The relationships calculated to estimate accuracy of diametric dimensions of the cylinders after plastic tension are given. It is shown that plastic tension of mandrelled cylinders reduces accuracy of holes with a diameter less than 5 mm by less than one accuracy grade. It is noted that the considered method of reducing residual stresses is the most appropriate to use in the manufacture of long cylinders.

mandreling, thick-walled cylinders, residual stresses, plastic tension, accuracy of holes.