Effects of alloying elements on the thermal fatigue properties of the 15 wt% Cr ferritic stainless steel weld HAZ

摘要

We investigated the effects of Nb, W, and V alloying elements on the thermal fatigue properties of the ferritic stainless steel weld heat affected zone (HAZ). Simulation of the weld HAZ and thermal fatigue testing were carried out using a metal thermal cycle simulator (MTCS) under a complete constraint force in the static jig. The fatigue life during cyclic heating and cooling in the temperature range of 200-900 ℃ was strongly related not only to precipitation and coarsening of MX type and Laves precipitates, but also to the Nb content in the solid solution and grain coarsening. The thermal fatigue life increased with Nb and W contents due to the increased amount of (Nb,Ti)(C,N) precipitates and a less coarsened Laves phase, respectively. Contrary to the results with Nb and W additions, there were no obvious effects of V addition.