Structural changes of tempered martensitic 9%Cr–2%W–3%Co steel during creep at 650°C

The structural changes in tempered martensitic 9Cr–2W–3Co (wt%) steel during creep tests at 650 °C were studied. The starting material was a solution treated at 1050 °C and subsequently tempered at 750 °C. The tempered martensite substructure consisted of a mixture of crystallites with a lath-type morphology and equiaxed subgrains. The tempering resulted in the precipitation of numerous second phase particles. MX-type precipitates were...