Dynamic Precipitation of Laves Phase and Grain Boundary Features in Warm Deformed FeCrAl Alloy: Effect of Zr

Abstract

Warm compression deformation of Fe-13.5%Cr-4.7%Al-2.0%Mo-0.70%Nb-0.40Ta (wt%) (FeCrAl) and Fe-13.5%Cr-4.7%Al-2.0%Mo-0.45%Nb-0.40Ta-0.11Zr (wt%) (FeCrAl-Zr) ferritic stainless steel was performed by a thermal simulation machine Gleeble 3800 at 600 °C and strain rates of 0.01-10 s −1 . Before deformation, all the samples were solution-annealed for 2 h at 1150 °C for FeCrAl alloy and 1250 °C for FeCrAl-Zr alloy. The strain rate has little or no effect on peak stress, and the precipitates in matrix or grain boundary precipitates (GBPs) have no difference in the samples deformed at the strain rate 0.01 s −1 and 1 s −1 both in FeCrAl and FeCrAl-Zr alloys. The addition of Zr increased the proportion of low-angle grain boundaries (LAGBs). The Laves phase in FeCrAl alloy precipitated uniform in the matrix, while in FeCrAl-Zr alloy Laves phase precipitated at grain boundary and formed GBP. The LAGBs and Σ3 coincident site lattice (CSL) grain boundary both increased in FeCrAl-Zr alloy, which possessed some beneficial properties such as high-temperature creep resistance to the Fe-Cr-Al alloy. More interesting, twins were created by warm deformation, which was difficult in typical bcc ferrite alloy. These results could be expected to provide guidance for subsequent warm working processes for the alloy.