Effects of alloying elements on the thermal fatigue properties of the ferritic stainless steel weld HAZ

In the present study, the effects of the addition of Nb, W, and V alloying elements on the thermal fatigue properties of the ferritic stainless steel weld heat affected zone (HAZ) were investigated. 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 to 900 °C was strongly related not only to precipitation and coarsening of MX type precipitates and Laves phase but also to the Nb content in the solid solution and grain coarsening. The thermal fatigue life increased with higher Nb and W contents due to more (Nb,Ti)C precipitates and a less coarsened Laves phase, respectively. Contrary to the results with Nb and W additions, there were no obvious effects on grain size and precipitation behavior associated with V addition.