High Temperature Time Dependent Allowable Stress and Isochronous Curves of an Austenitic Mn-Cr Steel

THE EVALUATION OF THE OPERATIONAL LIMITS OF THE AUSTENITIC STEELS BASED ON THE MN-CR SYSTEM IS AT PRESENT OF GREAT INTEREST IN ORDER TO ASSESS WHETHER THIS CLASS OF POTENTIALLY "LOW ACTIVATION" MATERIALS ARE SUITABLE AS STRUCTURAL MATERIAL FOR THE FIRST WALL, BLANKET AND SHIELD COMPONENTS OF AN EXPERIMENTAL AND OF A DEMONSTRATION FUSION REACTOR. THE PRESENT PAPER DESCRIBES THE RESULTS OF THE EVALUATION OF THE HIGH TEMPERATURE TIME DEPENDENT MECHANICAL BEHAVIOUR OF A COMMERCIAL STEEL OF THE FOLLOWING COMPOSITION IN WEIGHT %. MN 17.2, CR 10.1, SI 0.6, N 0.2 C 0.1, BALANCE FE. THE GENERAL AIM OF THE WORK WAS TO PRO- VIDE THE DESIGN ENGINEER WITH RELIABLE DESCRIPTION OF THE MATERIAL MECHANICAL PROPERTIES AT HIGH TEMPERATURE AND TO GUIDE THE ALLOY OPTIMIZATION PROCESS. THE CREEP AND STRESS-TO-RUPTURE TESTS WERE PERFORMED IN AIR IN TENSION ON CYLIN-DRICAL SPECIMENS OF GAUGE LENGTH AND DIAMETER OF RESPECTIVELY 50 AND 10 MM. THE TEST TEMPERATURES WERE 500, 550, 600, 650 AND 700 DEGREES C AND THE INITIAL APPLIED STRESS WAS CHOSEN IN ORDER TO ENCOMPASS TIMES-TO-RUPTURE FROM LESS THAN ONE HOUR TO OVER 10.000 HOURS. A FEW TESTS WERE PERFORMED AT AN INITIAL APPLIEDSTRESS CORRESPONDING TO A TIME-TO-RUPTURE EXCEEDING 20.000 HOURS. THE RESULTS OF THESE TESTS WERE USED AS CHECK POINTS TO VALIDATE THE EXTRAPOLATION OF THE STRESS-TO-RUPTURE, OF THE STRESS TO THE ONSET OF TERTIARY CREEP AND OF THE STRESS TO A CREEP DEFORMATION OF 1% UP TO A TIME OF 100.000 HOURS. EXTRAPOLATEDMETHOD BASED ON DIFFERENT TIME-TEMPERATURES PARAMETERS WERE EMPLOYED. THE EXPERIMENTAL AND EXTRAPOLATED DATA WERE USED TO TABULATE THE DESIGN STRESS BASEDON THE CREEP PROPERTIES WHICH, ACCORING TO THE ASME CODE CASE N 47 IS THE LOWESTOF. 1. THE MINIMUM STRESS TO RUPTURE 2. THE MINIMUM STRESS TO 1% CREEP STRAIN 3. THE MINIMUM STRESS TO ONSET OF TERTIARY CREEP DIVIDED BY A SUITABLE SAFETY FACTOR

MATERA Roberto; 

1995-03-15

JRC5244

https://publications.jrc.ec.europa.eu/repository/handle/JRC5244,