Li, Kejian
(School of Nano and Advanced Materials Engineering, Changwon National University, Changwon 51140, Korea)
,
He, Yinsheng
(School of Nano and Advanced Materials Engineering, Changwon National University, Changwon 51140, Korea)
,
Ma, Houyu
(School of Nano and Advanced Materials Engineering, Changwon National University, Changwon 51140, Korea)
,
Jung, Jine-Sung
(Power Generation System Group, Korea Electric Power Research Institute, Daejeon 34056, Korea)
,
Yang, Cheol-Woong
(School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 03063, Korea)
,
Lee, Je-Hyun
(School of Nano and Advanced Materials Engineering, Changwon National University, Changwon 51140, Korea)
,
Shin, Keesam
(School of Nano and Advanced Materials Engineering, Changwon National University, Changwon 51140, Korea)
Specimens of 304 stainless steel (304SS) were ultrasonic shot peening (USP) treated for refined and gradient microstructure. The specimens were then heat-treated at 500 degrees C, 600 degrees C, and 700 degrees C for 2 hrs, respectively. The hardness and microstructure of the untreated, shot peened,...
Specimens of 304 stainless steel (304SS) were ultrasonic shot peening (USP) treated for refined and gradient microstructure. The specimens were then heat-treated at 500 degrees C, 600 degrees C, and 700 degrees C for 2 hrs, respectively. The hardness and microstructure of the untreated, shot peened, and heat-treated specimens were investigated. Grain growth and nanoscale precipitation were apparent only in the 700 degrees C heat treatment specimen and the microstructural analysis was focused on that specimen. The gradient microstructure from the top were characterized as: (i) nanocrystalline layer, with very little grain size of similar to 200 nm, (ii) ultrafine grain layer in similar to mu m size with nanosize M23C6 in grain interior, and (iii) deformed coarse grain layer, with grains in similar to 50 mu m and the M23C6 were in the grain interior and boundaries. The nanoscale precipitates, distributed on the original lamellas and deformed twin boundaries, inhibited the grain growth, and strengthened the peening affected layers.
Specimens of 304 stainless steel (304SS) were ultrasonic shot peening (USP) treated for refined and gradient microstructure. The specimens were then heat-treated at 500 degrees C, 600 degrees C, and 700 degrees C for 2 hrs, respectively. The hardness and microstructure of the untreated, shot peened, and heat-treated specimens were investigated. Grain growth and nanoscale precipitation were apparent only in the 700 degrees C heat treatment specimen and the microstructural analysis was focused on that specimen. The gradient microstructure from the top were characterized as: (i) nanocrystalline layer, with very little grain size of similar to 200 nm, (ii) ultrafine grain layer in similar to mu m size with nanosize M23C6 in grain interior, and (iii) deformed coarse grain layer, with grains in similar to 50 mu m and the M23C6 were in the grain interior and boundaries. The nanoscale precipitates, distributed on the original lamellas and deformed twin boundaries, inhibited the grain growth, and strengthened the peening affected layers.
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