BRITTLE FRACTURE IN HEAT-AFFECTED ZONES OF GIRTH WELDS OFMODERN LINE PIPE STEEL (X100)

摘要

Girth welds of modern line pipe steel, such as X100, issued from a pulsed automatic gas metal arc welding, were tested tocheck their performance in artic temperature conditions.It is shown that an impact specimen at –20 °C with a notch placed inthe middle of the fusion line could break at low energy (<40 J).The brittle zone is located in the coarse-grained heat-affectedzone of the weld.The reproduction of two heat-affected zones with a thermal-mechanical simulator, Gleeble 1500, allows todetermine the mechanical behaviour of representative microstructures of the welded joint.Tension tests with or without notchand impact tests are performed between –196 °C and 20 °C.This experimental database is used to fit materials constitutiveequations which are used in a finite element code to predict the fracture of the welded joint.