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The evolution of eutectic carbide and granular pearlite, including secondary carbide and matrix ferrite, in 1.12C–8.1Cr–2.3Mo–1.08Si–0.32V alloy steel under spheroidization annealing is investigated. This procedure can be divided into two stages: austenitization in the range of 780–900 °C for 0.5–5 h and second annealing in the range of 740–780 °C for 3–7 h. The area fraction, size, number per unit area, and sphericity of carbides are analyzed under different annealing processes. The result indicates that the mean diameter of secondary carbides increases and the number of carbides per area decreases with the increase in temperature in two ranges of 780–900 and 740–780 °C. At >860 °C, the secondary carbide sufficiently spheroidizes, the eutectic carbide dissolves at the tip with a larger radius of curvature, and ferrite grains of the matrix are basically equiaxed. It can be found that the austenitizing stage plays a crucial role in nucleation and coarsening of secondary carbides, dissolution and segmentation of eutectic carbides, and recrystallization of matrix ferrite grains. The microhardness of the sample presents a decreasing tendency from fast to slow with the increase of the average diameter of secondary carbides. [ABSTRACT FROM AUTHOR]

Mechanical properties of 11Cr–3Co–2.3W steel are affected by various parameters, and normalizing temperature is an important parameter. OM, FESEM, EBSD, and TEM are carried out to study the microstructure evolution of 11Cr–3Co–2.3W steel normalized at different temperature ranging from 900 °C to 1150 °C and tempered at 780 °C. The tensile and impact properties are evaluated from the tempered specimens. The results show that an obvious grain coarsening occurs and the tempered strength of 11Cr–3Co–2.3W steel increases with increasing normalizing temperature. The specific strengthening mechanisms are discussed. The fracture morphology shows mainly dimples and cleavage facets, implying mixed‐mode of fracture mechanism when the normalizing temperature is up to 1050 °C. Normalizing at 1150 °C, the mixed‐mode of fracture mechanism is transformed to brittle fracture. [ABSTRACT FROM AUTHOR]