Some Insight on the Heat-affected Zone Strengthening Mechanisms in Duplex Stainless Steels

Abstract

The paper shows that the strengthening mechanisms at the duplex stainless steels' heat-affected zone (HAZ) are sensitive to the volume fractions of the different austenite morphologies and the orientation relationships of these austenite morphologies with ferrite. Also, the nitrogen content in these phases and the ferrite grain size significantly influence the strengthening mechanisms at the HAZs for the tested cooling times. Considering their morphologies and geometrical distributions, the different austenite volume fractions were calculated for each cooling time at the HAZ corresponding to two duplex stainless steels (UNS S31803 and UNS S32304). Predictions of the main macroscopic mechanical properties, as the yield and ultimate tensile strengths, were developed by knowing the features of the local phases. This approach clarifies the contribution of the different strengthening mechanisms during the strain at the simulated HAZs of the studied duplex stainless steels.

Keywords:
Duplex stainless steel; yield strength; heat-affected zone; strengthening mechanisms; microhardness