Fracture toughness of welds—effect of brittle zones and strength mismatch

摘要: Abstract The aim of this study is to examine the effect welding procedure, heat input in particular, on changes induced mechanical behavior welds an high strength quenched and tempered steel. Welds were performed by submerged arc welding, a steel RQT 601 with 25 mm thick, using inputs 2, 4.2 6.6 kJ/mm. COD/J specimens extracted transversely direction tested according BS 7448—Part 1 Part at temperature −20 °C. increase caused softening weld metal heat-affected zone, due microstructural coarsening. A decrease toughness was observed zone input. experimentally obtained value dimensionless factor m, relating J COD, similar that predicted equations established literature. general trend for COD size brittle sampled fatigue crack front observed, though some scatter always omnipresent.