Уточнение механизма повреждаемости металла длительно эксплуатируемых сварных соединений паропроводов

Abstract

Уточнили особенности повреждаемости метала сварных соединений паропроводов длительно эксплуатируемых в условиях ползучести, состоящих из сталей 15Х1М1Ф и 12Х1МФ. Предложена классификация повреждаемости, состоящая из пяти стадий. Рассмотрены механизмы образования пор ползучести и трещин усталости. Установлено, что наиболее интенсивно поры ползучести образуются на участке неполной перекристаллизации зоны термического влияния сварных соединений из теплоустойчивых сталей.The features of metal damageability of welded joints of steam lines, long operated under creep conditions, made of steels 15H1M1F and 12H1MF were specified. Damageability classification, consisting of five stages was proposed. The formation mechanisms of creep pores and fatigue cracks were considered. It was found that creep pores are formed most intensively in the area of incomplete recrystallization of heat-affected zone of welded joints made of heat-resistant steels. It was revealed that the metal destruction of welded joints has predominantly brittle intergranular nature. In the destruction area, the body of α-phase grains is affected by individual or locally grouped creep pores. It was found that the origination and development of fatigue cracks on the inner surface of steam lines have locally grouped nature. Their development is characterized by the absence of branching. Specification of metal damageability features of long-operated welded joints of steam lines will allow to reduce the damageability intensity, which provides increased lifetime.