Role of Microstructure in the Fast Fracture of Multipass Welds Deposited Using E-10018-M1 Electrodes

摘要

Weld metal deposited using MIL-E-10018-M1 electrodes maintains very good fractureresistance, despite being comprised of a seemingly deleterious microstructure which includes extensive networks of pro-eutectoid grain boundary ferrite in the as-deposited weld metal and brittle martensite-austenite particles in the intercritically reheated weld metal and heat affected zone. To reconcile this contradictory structure-property relationship the report focuses on the fractography and metallography of a MIL-E-10018-M1 multipass weld, fractured during an explosion bulge test. Martensite-austenite particles identified in the intercritically reheated weld metal and heat affected zones were found to play no part in the fracture process. Pro-eutectoid grain boundary ferrite was shown to be the preferred fracture path in the as-deposited weld metal however, it does not substantially reduce the overall fracture resistance of the multipass weld metal.