Variation of Creep Properties in HP Steel by Influence of Temperature

The structure and equipment of a plant can fail due to excessive plastic deformation and progressive degradation of their materials. Such is the case of petrochemical plants where, for example, pyrolysis furnaces operating at high temperatures are used and, as a consequence, materials are subject to creep conditions, which is one of the main mechanisms causing their failure.The aim of this paper is to study the creep behaviour of the HP type austenitic steel (Fe, 35Ni, 25Cr) microalloyed with Nb, which has high thermomechanical strength associated with the internal microstructure of the matrix. Tests were performed at temperatures and under stresses similar to service ones in order to identify acting degradation mechanisms. Simultaneously, microstructural evolution under the same time and temperature conditions as those of the tests was characterized.Torsional creep-rupture tests were conducted working in a temperature range of 1073 to 1273 K and under effective stresses between 40 and 90 MPa, keeping both variables constant during each test.