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J. Ocean Eng. Technol. 1990;4(2):112-164.    

Study on the Dislocation Behavior during Creep in 12% Chromium Steel
Oh Sea-Wook,Jang Yun-Seok
12% Cr 강의 크리이프중 전위거동에 관한 연구
오세욱,장윤석
동아대학교,한국중공업
© 1990 The Korean Society of Ocean Engineers     Open access / Under a Creative Commons License
Keywords: Dislocation, Subgrain, The Strength of Obstacle, The Velocity of Dislocation, Diffusion Coefficient
핵심용어: 전립, 아결정립, 장애물의 강도, 전립속도, 확산계수
Abstract
In order to check the effect of dislocation behavior on creep rate in 12% Chromium steel, 14 samples of different compositions were examined by creep rupture test, and subgrain sizes, distribution of dislocations and precipitates were checked. And, authors reviewed the behaviors of dislocations, the formation and growth of subgrains and precipitates during creep. The results are as the following: 1) Creep rates calculated by .epsilon. over dot = .rho.bv show 10-15% higher values than actual data measured. However, authors conclude that the density and velocity of dislocations together with subgrain size are important factors governing deformation during creep in 12% chromium steel. 2) The values of the strength of obstacles in the mobility of dislocations are more clearly depended on the effective stress in the range of $10{pm}5kgf/mm^{2}$ and increase with the increase of temperature. 3) Creep rates decrease with the smaller sizes of subgrains formed and can result in the longer creep rupture lives(hours). The smaller subgrains can be made by forming shorter free gliding distances of dislocations with very fine precipitates formed in the matrix during creep by applying proper alloy design. 4) Dislocation mobility gets hindered by precipitates occurring, which are coarsened by the softening process governed by diffusion during long time creep.


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