Microstructural Stability During Creep Exposure of 9Cr-1Mo Steel Treated at Different Normalization Temperatures

Chatterjee, A. K.; Modak, Pranabananda; Barat, Kaustav; Chakrabarti, Debalay; Mitra, Rahul

doi:10.1007/s11665-019-04074-3

Cited by 4 publications

(1 citation statement)

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“…9–12%Cr heat‐resistant steels are critical materials used for thick‐section boiler components and turbines because it offers the best combination of high creep strength, high resistance against thermal fatigue, and high steam oxidation resistance at elevated temperatures. [ 1–4 ] The primary ways to enhance the creep resistance for 9–12%Cr steels are to strengthen the martensitic lathy structure by precipitates, dislocation, and solid solution atoms. [ 3,4 ] Therefore, it is of considerable significance to study the evolution of microstructure during tempering as the final heat‐treatment step directly determines the comprehensive mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Effect of Tempering Temperature on Microstructure Evolution and Hardness of 9Cr1. 5Mo1CoB(FB2) Steel

Zhang

Shen

et al. 2021

steel research int.

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The microstructure evolution and hardness variation of FB2 steel influenced by tempering are investigated. The results show that water‐cooling from 1100 °C produces lathy martensite microstructure. After tempering at 500 °C, the steel exhibits a martensite structure with 4.2% needle‐like Fe3C particles. The (Cr, Mo)2C and Cr‐rich M7C3 particles are detected in the sample tempered at 570 °CAs the tempering temperature enhances from 620 to 700 °C the (Cr, Mo)2C and Cr‐rich M7C3 in the matrix are replaced by Cr‐rich M23C6. Besides, the (V, Nb)C particles are identified in samples tempered above 620 °C. Thus, the evolution of carbides in FB2 steel during tempering can be summarized as: Fe3C→(Cr, Mo)2C + Cr‐rich M7C3→(Cr, Mo)2C + Cr‐rich M7C3 + Cr‐rich M23C6→Cr‐rich M23C6. Furthermore, the results suggest that M3C, M2C + M7C3, M23C6, and MX have high reaction rates at 500, 570, 620, and 700 °C respectively. In addition, the dislocation density reduces from 6.8 × 1014 m−2 to 2.1 × 1014 m−2, and the volume fraction of carbides increases from 4.2% to 12.6% with increasing temperatures from 500 to 700 °C leading to hardness decrease from 485 to 284 Hv. Finally, the quantitative relationship between the hardness and microstructure evolution during tempering is discussed.

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Section: Introductionmentioning

confidence: 99%