THE EFFECT OF SERVICE CONDITIONS ON CRACK INITIATION AND PROPAGATION IN WELDED JOINT OF HIGH-ALLOY STEEL X20

摘要

The aim of these investigations was to establish the effect of service conditions (service life, temperature) on behaviour of base metal and welded joint of high alloy X20, designed for operation at elevated temperatures and affected by variable loading. The effect of service conditions was analysed by testing the new material and material that had been in service for 116,000 hours. Investigations of the new material and base metal that had been in service as well as of the components of welded joint (weld metal and heat-affected zone) made of high alloy steel included determination of the parameters of fatigue-crack growth both at room and at elevated temperature. The results of these investigations should provide practical contribution toassessment of quality of base metal of the components of welded joint of steel X20, aimed at revitalisation i.e. assessment of strustural integrity and extension of service life of vital components, high-alloy steel thermal power plants operating at elevated temperatures.