LOW CYCLE FATIGUE PROPERTIES AND IMPACT TOUGHNESS OF ADVANCED 10 CR STEEL WITH HIGH BORON AND LOW NITROGEN CONTENTS

摘要

9-12%Cr martensitic steels can be applied to the next highest temperature components such as boiler tracts, steam pipelines and turbines of advanced ultra-supercritical power plants with steam temperatures of 650°C. New 10%Cr martensitic steels with high B and low N contents can be a worthy candidate for use in production because it has superior creep resistance. At the same time, resistance to cyclic and dynamic loads is very important. In this work, we studied the low cycle fatigue (LCF) properties at room and elevated (500-650°C) temperatures and Charpy impact toughness at temperatures ranging from -196... 100°C of advanced 10% Cr martensitic steel with high B and low N contents. The effect of new alloying scheme and corresponding pecularities of M_(23)C_6 carbides on the low cycle fatigue resistance and impact toughness of the 10%Cr martensitic steel is analyzed. It is revealed that fine and densely distributed carbides has no effect on the fatigue resistance except for the slight improvement of fatigue life at small strain amplitudes and shift the ductile-brittle transition temperature (DBTT) to higher but satisfactory value of + 10°C as compared to other high-chromium martensitic steels.