Creep Behavior in A Newly Developed Heat Resistant Austenitic Stainless Steel

• UNS S31035 austenitic stainless steel grade is a newly developed advanced heat resistant material for use in coal fired boilers at metal temperatures up to 700 °C. This new grade that has recently got two AMSE code cases shows good resistance to steam oxidation and flue gas corrosion and high creep rupture strength. This paper will mainly focus on the characterization of long term structure stability and performances such as the creep behaviors at different temperatures for up to 86,000 h at high temperatures. The creep damage mechanisms were studied using electron transmission microscopy, electron backscatter diffraction, and electron channeling contrast image analysis. The results show that the creep strength is related to the intragranular nano particles that act as obstacles for dislocation movements. Plastic deformation and transgranular fracture is the main creep fracture mechanism in the creep test samples of UNS S31035. The material has good creep ductility by formation of twins during the creep test. This material has been installed and tested in several European power plants, and has shown good performance. The material is an excellent alternative for superheaters and reheaters in future high-efficient coal fired boilers with design material temperatures up to 700 °C, instead of more costly nickel based alloy. 

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Heat resistant austenitic stainless steel

superheater

A-USC

creep

coal-fired power plants

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