鋼管圓周溶接部의 溶接殘留應力 分布에 對한 考察

權鍾完 慶北工業專門大學 1984 論文集 Vol.21 No.-

Stress due to circumferential V-butt welds, made with six passes in 150mm O.D., 10mm wall thickness cylindrical Cr-Mo alloy pipe, were determined by Sachs boring-out method. The effect of residual stress relief procedures upon to magnitude of stresses and distributions in weld, were investigated. 1. The axial stresses in the weld were founded to be tensile at the innersurface and compressive at the outersurface with maximum compressive stress occurring a short distance below the outersusface. 2. The effect of residual relief stresses, residual stress distributions are same but magnitude is very small by low yielding strength, analyzing time and relaxation of creep. 3. The hardness of welding line were investigated. The stress relief procedures upon to value of hardness is less then received welding. Resulting, magnitude of residual stresses in annealing pipe were founded small value.

2相 Stainless鋼의 異種熔接에 對한 靜的 强度特性

權鍾完 慶一大學校 1986 論文集 Vol.2 No.1

Recent trends in the fabrication of industrial plant have led to the increased use of welding for joining materials of different composition. In this study, is research of static strength for welding bond by dissimilar metals(25cr-5Ni stainless steel versus SM41 steel). Through investigation, we found phenomenon of maxium true strength and toughness decreasing near the bonded part of welding joint. It was caused by brittle layer formed in the deposite metal along the fusion line. We recognized accurate time for PWHT(post welding heat treatment 1hr or 2hr.) Brittle layer of welding bond is recovered by PWHT in this case.

SiC 粒子 强化 알루미늄 複合材料에 대한 疲勞龜裂進展 特性

권종완 경일대학교 산업기술연구소 1993 産業技術硏究所 論文集 Vol.3 No.-

본 연구는 실리콘 카바이드 입자의 강화조직인 7075-미 25%Si체를 대상으로 상온에서 피로 균열진전 대하여 Short Crack 특성과 금속조직과 상호관계를 연구하였다. 균열의 발생은 실리콘 카바이드 강화조직 입계에서 발생하였으며 그 원인은 고밀도의 강화입장화 알루미늄과 불완전한 결합에 기인한다. 균열의 진전은 K와 관련하여 응력레벨에 무관하며 금속조직의 특성의 지배를 받는다. short crack 의 발생은 long crack 의 하한계치에 비하여 낮은 k 영역에서 나타났으며 균열진전속도는 서로 유사하였다. 이것은 전자가 균열선단에서 균열의 성장은 주로 입자상호간의 금속조직적인 영향에 의하고 후자에서 일반적으로 나타나는 균열닫힘현상의 영향을 거의 받지 않기 때문이다.

탄화규소 강화 알루미늄 (SiC/Al)복합재료의 피로파괴 특성에 관한 연구

權鍾完 慶一大學校 1995 論文集 Vol.12 No.2

A study of short and long crack fatigue crack growth has been carried out on three SiC Reinforced metal matrix Al composite materials manufactured by a spray deposition technique. Both short and long crack growth in 8090 reinforced with particulate were matrix dominated with little direct interaction with the particulate while short and long crack growth in 7075 25% vol. SiCp was matrix dominated with crack growth occurring at the particle matrix interface. The 7075 25% vol.SiCp had marginally superior resistance to fatigue crack growth at r=0.1 than 8090 14% vol. SiCp and significantly better than 8090 3% vol. SiCp while R=0.65 the 7075 25% vol. SiCp had sinificantly superior near threshold resistance to fatigue crack growth compared to the 8090 composites but inferior resistance in the stable crack growth regime. Crack closure and modules increases were identified as important factors influencing long fatigue crack growth behaviour.

Sic粒子强化 알루미늄 複合材料에 대한 疲勞龜裂 傳播 下限界 特性과 微視的 機構

權鍾完 慶一大學校 1993 論文集 Vol.9 No.1

A study of short and long fatigue crack growth has been carried out on 7075-Al and 7075-Al-SiC particle reinforced composite materials. The addition of particulate reinforcement to 7075-Al matrices caused an increase in modulus while strength and ductility decrease. In the heavily reinforced composities, 7075Al-25% SiCp, short fatigue crack iniation was associated with residual porosity caused by incomplete consolidation in regions of high particulate density. Short fatigue crack growth data ere generated for 7075Al-25% SiCp at 290 MPa < σmax< 371 Mpa. The addition of SiC particulate reinforcement did not cause significant differences in short crack growth rates and independant of stress level. Evidence to support a mechanism of crack growth consisting of crack tip blunting following by shear bend cracking has been presented, as a result of In Situ SEM examination of crack tips at high resolution. Long and short crack growth occurring at the particle/matrix interface.

2상계 스테인리스강 용접부의 피로크랙 전파특성 (II) -하한계치 근접에서의 전파특성-

권종완,김상대,이택순 대한기계학회 1989 대한기계학회논문집 Vol.13 No.1

본 연구에서는 2상계 스테인리스강의 모재,용접재 및 용접후 열처리재 3종류의 경우에 대하여 피로크랙 전파특성을 피로크랙의 하한계치 근방에서 금속조직적인 영향을 검토하기 위하여, 각 조건에 대한 피로크랙 전파속도의 하한 계치를 구하였고 피로식검후의 파단면을 주사전자현미경(SEM)으로 관찰하였다. 용접재에 대하여는 용착부 부근 용접열영향부의 입경측정, .alpha./.gamma.상의 체적비교율의 변화량 측정 및 용접재와 용접후열처리재의 잔유응력분포측정을 통하여 피로크랙의 하한계특성에 미치는 여러가지 영향인자에 대하여 검토하였다. Near-threshold fatigue crack-growth behavior at room temperature for a duplex stainless steel weldments was investigated to evaluate the effect of load ratio, microstructural change, and residual stresses. Near-threshold fatigue crack propagation behavior is found to show a marked sensitivity to .alpha./.gamma. phase ratio, and little residual stress effects. Threshold values in the heat affected zones are higher than those of base metals and threshold values for crack growth decrease with increasing the load ratio in the base metals and weldments. The fractrographic features in base metals, weldments and heat affectred zones were discussed in terms mechanism of crack growth.

變分法에 衣한 體積一定下의 形狀決定에 對한 考察

權鍾完 慶北工業專門大學 1983 論文集 Vol.20 No.-

It is very important for structure analysis from the viewpoint of structurl design to know the appropriate shape of beam element. In this paper, The variational approach is formulated in two demensional isotropic plane stress problem and calculate the appropriate shape of element. An example problem, the calcuiation of thickness is showen for simple beam element under the concentrate load. In this study, following information is obtained. 1) An optimal shape condition is expressed by the term fo energy density quantity from principle of variation and example calculation coincides with the solution of uniform stress. 2) we presume the example calculation which is applied more compricate shape calculation problem.

鑄鐵 미끄럼摩擦의 摩耗에 對한 硏究

權鍾完 慶北工業專門大學 1979 論文集 Vol.16 No.-

Wear which occurs in the slidng of metal pair is very complicated. Because it is made up the various factors which are combined in a complicated way. In this paper, the relation between wear occurs in matal pair which had been proved depend mainly on the flow pressure of material and Holm's wear equation W=KPL/?? examined by wear test of cast iron. The wear test are carried out under the dry condition using upper and lower test pieces of cast iron the same quality. We proved that material hardness dominated surface temperature induced by frictional temperature. By expressing the hardness as a function of Olad and sliding speed. Results are summarized as follows. 1) ?? could be obtained theoretically from Holm's equation, W=KPL/?? where ?? is wear rate P the load V. the sliding speed. ?? : the hardness at room temperature. C constant depending on the properties of material ?? : flow pressure. 2) The equation did not hold at high load and speed, this cause is deduced that some factors other than the hardness act predominantly on the wear process.

二相 스테인리스鋼 熔接部의 疲勞龜裂傳播 特性과 微視的 機構

權鍾完 慶一大學校 1989 論文集 Vol.5 No.1

An experimental study was carried out to identify the fatigue crack propagation behavior of duplex stainless steel weldment. Experimental works were performed under stable crack propagation in room temperature and substitute ocean water was also studied. Experiments were studied to give insight of phenomennological understanding in terms of micro-structural changes. The crack propagation behavior was found to be dependent on phase ratio(α/γ). The crack propagation rate in welding zone first, in base-metal was second. The crack propagation rate in substitute ocean water was found to be faster than that obtained in air at room temperature. This may be caused by the corrosion of the fatigue fracture surface through chemical reaction. The crack propagation rate estimated by the measurement of striation spacing was higher than that obtained by crack length measurement in low △K region, however, both crack propagation rates were found to be identical.

三相스테인리스鋼의 溶體化處理溫度에 對한 靜的强度特性

權鍾完 慶一大學校 1988 論文集 Vol.4 No.1

Charactristics of static strength in duplex-stainless steel has been investigated withtemperature of solution heat treatment. In higher temperature, volume of ferrite phase and grain size increased in stainless-steel. At 1623 K, duplex-stainless steel is changed ferrite phase wholy. Static strength and hardness is proportion to volume of ferrite phase. At 1300K, static strength, ductilenss increased significantly. Increasing of cooling rate decreased static strength. The static strength revealed a very large influence of solution temperature at 773K.