Influence of Spinodal Decomposition on Impact Strength of SS2377 Duplex Stainless211 Steel Weldments. Part 2

摘要

In order to illuminate the possible effect of residual stresses on the kinetics211u001eof spinodal decomposition of duplex stainless steels weldments, specimens were 211u001esubjected to ageing under load. Both base metal and weld-simulated structures 211u001ewere investigated. It was found that the embrittlement of the base metal was only 211u001edependent on the stress state and load to a limited degree. However, the single-211u001ephase ferrite, designed to have the composition of the base metal ferrite, 211u001edisplayed more rapid embrittlement in the case when aged under load than when 211u001eaged under unloaded conditions. The simulated HAZ microstructure, consisting of 211u001eequiaxed ferrite grains with grain boundary austenite and some Widemanstatten 211u001eaustenite, typical of high temperature HAZ after full ferritization, displayed a 211u001emore rapid decrease in impact energy after ageing than did the base metal. In 211u001eorder to evaluate the possible differences in ageing response in terms of 211u001espinodal decomposition between weld metal and base metal, an attempt was made to 211u001equantify the demixing by an atom probe investigation. A limited effect on 211u001edemixing behavior was observed with a slightly larger maximum compositional 211u001eamplitude and wavelength for the weld metal ferrite than for the base meal 211u001eferrite.