Specimen Size and Orientation Effects on the Toughness of Steel Weldments

Abstract

This paper deals with the measurement of the room temperature fracture toughness of 25-mm thick HY130 steel shielded-metal-arc weldments. The multipass butt welds were tested using different specimen geometries and orientations, and after various post-weld stress relief heat treatments. Where appropriate, comparisons are made between KIc and JIc data, including estimates based on both CTOD and stretch zone size measurements, for both parent metal and fusion zone material. Measured toughness for plate depends on whether the specimen tears at or before limit load, and thus on specimen size, but is independent of orientation and unaffected by thermal stress relief. Maximum load J for weldments is independent of specimen size or orientation, but CTOD decreases as specimen size decreases. Welds slowly cooled after stress relieving fail in a brittle manner, with very low CTOD values, even though the nominal critical stress intensities exceed 100 MPam.