PREDICTION OF THE CREEP BEHAVIOUR OF A 21CR-11NI-0.17N STEEL BASED ON CONSTANT STRESS CREEP TESTS

摘要

A series of creep tests at 973 K under constant stress condition were carried out to characterise the high temperature behaviour of 21Cr-11Ni-0.17N austenitic stainless steel. In addition, constant load and a variable stress creep test were performed. Microstruc-tural observations on crept specimens showed the presence of inter-granular and surface cracks. Constant stress creep curves were used to determine the material parameters of a viscoplastic constitutive model based on a backstress and continuum damage approach. The predictive capabilities were checked by its application to load controlled creep tests and a test with variable stresses. The description of constant stress or constant load creep conditions is fairly good. The model satisfactorily describes also sudden load changes.