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정순억,Jeong, Sun-Eok 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.10
It is important to ensure the reliability of the first localized reactor vessel steel. To satisfy with this purpose, a study on the impact/hardness, low cycle fatigue(LCF), crack growth rate(da/dN) and fracture toughness( ) of base material(BM) and weld metal(WM) were performed under room temperature air and corrosion conditions. A summary of the results is as folows : (1) Charpy impact absorbed energy of BM was the highest value, heat affected zoon(HAZ) and the lowest, WM. The hardness of BM was similar to HAZ. (2) Coefficients of Manson equation using the monotonic tensile test data were obtained for the present material. (3) The effects of stress ratio and ambient (120.deg. C and NaCl) condition on da/dN were investigated, da/dN with NaCl condition expressed the highest value. (4) The results of Charpy V-notch impact test had good correlation with $K_{IC}$ characteristics and the lowest curve of $K_{IC}$ for BM was derived, more researches about WM and HAZ are required hereafter.
12%Cr 로터강의 고온 크리프 변형 경화 및 회복에 관한 연구
정순억 慶尙大學校 1996 論文集 Vol.35 No.2
An extensive experimental tests(500, 600 and 700℃) on 12%Cr steel to examine Bailey-Orowan's creep recovery equation ε=r/h, where ε is the steady state creep rate, r is the recovery rate and h is the strain hardening coefficient were measured, the value of h calculated from this equation was compared with that measured in a room temperature tensile test, and the experimental results were as follows: 1) The application of Bailey-Orowan's recovery equation to steady state creep was considerably coincided with expremental results. 2) The stress sensitivity of ε was mainly due to the influnces of stress on r. 3) h was decreased several fold during the transient creep.
정순억 慶尙大學校 1999 論文集 Vol.38 No.-
This thesis studied whether friction welding of SUP9A, torsion bar material could be accomplished or not. And then optimum welding conditions were examined and leaded through tensile, impact, torsion and hardness test after postweld heat treatment of the actual field condition. Obtained results were as follows; Linear relationship was existed between heating time and total upset, and a quadratic equation model could be made between tensile strength and heating time. Optimum welding conditions with fine structure were as follows in case total upset(U)=8.3mm; the number of rotations(n)=2,000 rpm, heating pressure(p1)=80 MPa, upset pressure(p₂)=200 MPa, heating time(t₁)=4 sec, upset time(t₂)=3 sec.
1%CrMoV 로터강의 파괴인성에 미치는 개제물의 영향
정순억,Jeong, Sun-Eok 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.9
This thesis studied that seven kinds of residual elements(inclusions) had influenced on fracture toughness($K_{IC}$) obtained by Begley-Logsdon and Rolfe-Novak model equation using tensile an d impact test data of I%CrMoV HP(high pressure) rotor steel. $K_{IC}$ design curve of ASME and fracture surface by SEM were also considered, obtained results are summarized as follows $K_{IC}$ was linearly increased with increase of temperature, effect of the inclusions was significantly over FATT. $K_{IC}$ at lower shelf temperature was quantitatively related to yield strength and was agreed well with Begley's equation. It was difficult to determine $K_{IC}$ because of specimen size and tester capacity at upper shelf temperature, but for this view point Rolfe-Novak's equation was useful. The degree of brittle fracture was dependent on FATT fundamentally, adding S, Sb to matrix decreased impact energy and adding Cu, As increased yield(tensile) strength, and the influence of the others minority inclusion was comparatively insignificant.