Creep behavior of austenitic stainless steel weld metals as a function of ferrite content

Abstract

Four types of modified and commercial E308H and E316H weld deposits with Ferrite Number (FN) in the range of 0–5.7 were investigated for creep behavior at stress levels between 70 and 240 MPa, with a range of temperature 550–700 °C. After creep testing, sigma phase was found in commercial E308H and E316H creep samples, significant carbide evolution from modified E308H and E316H with 0 FN creep samples distribute in a random and a chain along the substructures and grain boundaries, respectively. The creep results show that, for E316H weld deposits, modified samples with 0 FN, even though containing microfissures, have a higher creep strength than the fissure-free commercial samples with a higher ferrite content. This can be attributed to the beneficial effect from the carbides on dislocation barriers and the detrimental effect on hard and brittle sigma formed in commercial E316H. Fissure-containing modified E308H has a lower creep strength than fissure-free commercial sample because of the propagation paths provided by fissures and the minimal effect on the randomly distributed carbides.