The Analysis of the Post-Operation Microstructure and Mechanical Properties of the Similar Welded Joint

Abstract

The test material was a specimen sampled from sections of a pipe operated for 41,914 hours at a temperature of 575°C and under a steam pressure of 28.2 MPa. The specimen subjected to metallurgical tests was a welded joint made of austenitic steel TP347HFG. The non-destructive tests and the macroscopic tests confirmed the lack of any welding imperfections. The test joint represented quality level B in accordance with related standard requirements. The microstructural tests of the heat-affected zone (HAZ) revealed the presence of the fine-grained austenitic structure with numerous precipitates on grain boundaries – probably M23C6 carbides. In spite of long-lasting operation, the mechanical properties of the test welded joint were high and did not exceed the standard-related requirements concerning the base material.