Creep Behavior of the Newly Developed Advanced Heat Resistant Austenitic Stainless Steel Grade UNS S31035

The UNS S31035 austenitic stainless steel grade is a newly developed advanced heat resistant material for use in coal fired boilers at material temperatures up to about 700°C. This new grade has good resistance to oxidation and hot corrosion, and shows higher creep rupture strength than other austenitic stainless steels available today. This paper will mainly focus on the study of the creep mechanisms in this grade from 550°C up to 800°C by using TEM, SEM and LOM. The creep mechanisms at different temperatures and loading conditions have been identified. The interaction between dislocations and precipitates and their contribution on the creep rupture strength and fracture mechanisms have been discussed. In this paper, different models have been used to evaluate the long-term creep behavior of the grade. A creep rupture strength near 100MPa at 700°C for 100 000h has been predicted. This makes it an interesting alternative for super-heaters and reheaters in future high-efficient coal fired boilers.