MEASUREMENT OF THROUGH-THE-THICKNESS VARIATIONS OF MECHANICAL-PROPERTIES IN SA508 GR.3 PRESSURE-VESSEL STEELS USING BALL INDENTATION TEST TECHNIQUE

The through-the-thickness variations of mechanical properties in SA508 Gr.3 pressure vessel steels were measured using the automated ball in dentation (ABI) test technique. Key mechanical properties, such as the yield strength, ultimate strength, flow curve and hardness, were eval uated from indentation load-depth curves. The mechanical properties me asured were location-dependent and the steepest gradients in the distr ibutions of the mechanical properties appeared in the near-surface reg ions. The maximum through-the-thickness variations of the mechanical p roperties were in the range of 5-20% and they depended on the manufact uring process as well as the original wall thickness. It was concluded that the through-the-thickness variations in the mechanical propertie s were mainly caused by the location-dependent cooling rate during wat er quenching in the quality heat treatment which consisted of water qu enching and tempering. (C) 1998 Elsevier Science Limited. All rights r eserved.