Effect of structure changes takina place during exploitation on impact strength of heat-resistant steel

A study was made on the effect of structural changes on Asub(H) metal impact strength after tau different periods of operation under conditions of increased temperatures and stresses. Casting of 15Kh1M1FL steel presented material under investigation. It is shown that the extent of interface occupied by carbides, with growth of which Asub(H) value decreases, is one of the main structural factors, affecting impact strength. Impact strength value is interrelated with microhardness difference in the body and at grain boundary, taking place owing to accelerated diffuse process rate and damage accumulation at the grain boundary during long action of temperature and stresses. Processes of carbide separation at grain boundaries and damage accumulation are activated with increase of metal operation period under conditions of increased temperatures and stresses