Improved Tensile Properties of Micro-grain Casting K447A Alloy

Wang, Yue; Wang, Xitao; Li, Rui; Hu, Ping; Xiao, Chengbo; He, Jinshan

doi:10.1007/s11661-022-06894-w

Cited by 4 publications

(1 citation statement)

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“…As a certain volume fraction, γ′ with a closer size to the critical diameter provides a higher strengthening effect. For MAR-M247 alloy, the critical diameter is calculated to be 74 nm [ 36 ], smaller than those of γ′ phases in all aging state samples. Therefore, with the coarsening of γ′ phases, the effect of precipitation strengthening is gradually weakened.…”

Section: Resultsmentioning

confidence: 99%

Effect of Cooling Rate on the Microstructure and Mechanical Property of Nickel-Based Superalloy MAR-M247

Wang,

He,

et al. 2024

Materials

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Heat treatment is an important process for optimizing the microstructures of superalloys, and the cooling rate after solid solution treatment is one of the most critical parameters. In this work, we treated solid solution MAR-M247 alloys with water quenching, air cooling, and furnace cooling. Microstructure characterization, hardness, and room temperature tensile tests were conducted to investigate the effect of cooling rate on the microstructure and mechanical properties of MAR-M247 alloys. The results showed that the cooling rate after solid solution treatment mainly affected the precipitation behavior of the secondary γ′ phase, but it had few effects on other microstructure characterizations, including grain size, γ/γ′ eutectic, and MC carbide. The water-quenched sample had the highest cooling rate (400 °C/s) and hardness (400 HV) but suffered from premature fracture because of quenching cracks. A further decrease in cooling rate from 1.5 °C/s to 0.1 °C/s deteriorated hardness (384 HV to 364 HV) and yield strength (960 MPa to 771 MPa) but increased elongation (8.5% to 13.5%). Moreover, the deformation mechanism was transformed from dislocation shearing to Orowan bypassing. The decreased yield strength was mainly due to the weakened precipitation strengthening resulting from γ′-phase coarsening. The improved elongation was attributed to not only the higher work-hardening index caused by interface dislocation networks but also the more uniform deformation, which delayed necking.

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Section: Resultsmentioning

confidence: 99%