Investigation of Thermal Embrittlement of 17-4PH Stainless Steel Main Steam Isolation Valves

Macha, John; Kirby, Matthew; Hickey, William F.; Riha, David S.; Alston, James K.; Holden, Benjamin B.

doi:10.1007/s11668-021-01199-3

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…Due to its good welding performance, high mechanical strength, and good corrosion resistance, martensitic precipitation hardening stainless steel with low carbon content, particularly Cu-added 17-4 PH stainless steel and 15-5 PH stainless steel, has been extensively employed in harsh environments, such as in the petroleum, chemical, and nuclear energy industries [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. As a kind of typical precipitation alloy, this material can be hardened by fine precipitates with a high number density after a series of thermal treatments, including high temperature solution treatment (usually at 1040 °C for 1–4 h), then multi-stage aging at temperatures between 450 °C and 620 °C for several hours.…”

Section: Introductionmentioning

confidence: 99%

The Microstructure and Mechanical Properties of a 15-6 PH Stainless Steel with Improved Thermal Aging Embrittlement Resistance

Lv,

Yin,

Bai

et al. 2024

Materials

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The evolution of the microstructure and the mechanical properties of a 15-6 martensite precipitated hardened (15-6 PH) stainless steel after thermal treatment and long-term aging at 480 °C were investigated. Compared with 17-4 PH steel, the content of Cr decreased and Ni increased in the newly developed 15-6 PH steel; therefore, reversed austenite formed after thermal treatment at 620 °C of the solution-treated 15-6 PH steel. Although the reversed austenite may reduce the strength of the steel, it is very beneficial for the inhibition of the aging brittleness of the steel. During the accelerated thermal aging at 480 °C, the Cu-rich phase gradually coarsened, and its crystal structure changed, while the reversed austenite phase sightly increased and the Charpy impact energy maintained a rather high value. The increase of the reversed austenite content can offset the reduction of the strengthening effect of the Cu-rich phase and therefore maintain an excellent impact property of the material after thermal aging.

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Section: Introductionmentioning

confidence: 99%

The Microstructure and Mechanical Properties of a 15-6 PH Stainless Steel with Improved Thermal Aging Embrittlement Resistance

Lv,

Yin,

Bai

et al. 2024

Materials

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“…Some long-term and medium-temperature aging experiments show that the G phase, as an intermetallic compound, is usually precipitated with spinodal decomposition [ 6 ]. Additionally, nanophase precipitation occurs during the thermal aging process of 17-4PH martensitic steel, with the precipitation and growth of Cu-rich phases acknowledged as a key factor contributing to 17-4PH heat aging embrittlement [ 7 , 8 ]. Aghaie-Khafri et al studied the phase separation and precipitation process of 17-4PH under long-term aging conditions and found that the precipitation and growth of Cu could be the cause of aging embrittlement.…”

Section: Introductionmentioning

confidence: 99%

In Situ Characterization of 17-4PH Stainless Steel by Small-Angle Neutron Scattering

Yan

Wang

et al. 2023

Materials

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17-4PH martensitic steel is usually used as valve stems in nuclear power plants and it suffers from thermal aging embrittlement due to long-time service in a high-temperature and high-pressure environment. Here, we characterized the evolution of microstructures at the nano-scale in 17-4PH steel by in situ small-angle neutron scattering (SANS) with a thermo-mechanically coupled loading device. The device could set different temperatures and tensile so that an in situ SANS experiment could dynamically characterize the process of nanoscale structural changes. The results showed that with increasing thermal aging time, the ε-Cu phase precipitates and grows as the temperature is 475 °C and 590 °C, and the ε-Cu phase is spherical at 475 °C but became elongated cylinders at 590 °C. Moreover, the loading stress could aid in the growth of the ε-Cu phase at 475 °C.

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Analysis of Regulating Valve Stem Fracture in a Petrochemical Plant

et al. 2023

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This paper investigates the failure of a regulating valve stem in a petrochemical plant, which was mainly caused by vibration fatigue under small opening conditions. The fractured valve stem was analyzed using macroscopic analysis, chemical composition analysis, mechanical property analysis, metallographic analysis, fracture surface observation, and energy spectrum analysis. Additionally, fluid-structure interaction (FSI) modal analysis was used to investigate the failure of the regulating valve. The results indicate that the valve opening had a direct impact on the vibration of the valve body, which, when operated at small openings, led to fatigue fracture at the step of variable cross-section. The paper suggests a smooth transition treatment be performed at the variable cross-section of the valve stem to avoid stress concentration. Although this study is limited to a specific case, it provides valuable insights for the failure analysis of valves operating at small openings.

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Investigation of Thermal Embrittlement of 17-4PH Stainless Steel Main Steam Isolation Valves

Cited by 3 publications

References 6 publications

The Microstructure and Mechanical Properties of a 15-6 PH Stainless Steel with Improved Thermal Aging Embrittlement Resistance

The Microstructure and Mechanical Properties of a 15-6 PH Stainless Steel with Improved Thermal Aging Embrittlement Resistance

In Situ Characterization of 17-4PH Stainless Steel by Small-Angle Neutron Scattering

Analysis of Regulating Valve Stem Fracture in a Petrochemical Plant

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