SUS 304 鋼의 SCC 特性에 미치는 pH의 영향

林祐助 釜山水産大學校 1985 釜山水産大學 硏究報告 Vol.25 No.1

一定 變位 引長試驗機를 利用하여 pH가 SUS 304 鋼의 SCC 初期 潛伏期間에 미치는 영향을 硏究한 結果 다음과 같은 結論을 얻었다. 1) 용접열 영향부의 SCC 初期 潛伏期間은 모재보다 용접열 사이클로 因한 銳敏化현상 및 軟化에 의해 빨라진다. 2) 용접열 영향부의 應力腐蝕균열은 MgCl₂溶液의 溫度상승에 의한 陽極의 活性에 기인된다. 3) pH를 높게 함으로써 SCC 初期 潛伏期間은 크게 지연된다. The characteristics of stress corrosion cracking of SUS 304 stainless steel were studied with the specimens of the constant displacement type under the environment of various pH(MgCl₂aqueous solution). Main results obtained are as follows: 1) The latent time of crack initiation of weld heat affected zone in the stress corrosion cracking zone has rapid for phenomenon of sensitizing and softening caused by weld heat cycles than that of base metal. 2) The stress corrosion cracking of weld heat affected zone was owing to the active of anode by increasing temperature of MgCl₂aqueous solution. 3) The latent time of crack initiation is delayed in the stress corrosion cracking under high condition of pH.

배관의 캐비테이션 침식-부식 특성에 관한 연구

임우조,황재호,김윤곤 釜山水産大學校 1994 釜山水産大學 硏究報告 Vol.34 No.1

In this study, the steel pipe piping water(SSPW) and SPPW on weldment were tested by using of a cavitation erosion - corrosion test appartus with nozzle(water tunnel type) and were investigated under the marine environment of liquid. The main results obtained were as follows 1) The corrosion - erosion of weldment is more susceptible than that of base metal. 2) The weight loss rate of heat affected zone of weldment can be largely improved by the preheat, dry of base metal and electrode before welding. 3) The electrode potential becomes noble by the pre-heat, dry of base metal and electrode before welding, and the corrosion current density is decreased.

캐비테이션 손상에 미치는 기포 거동에 관한 연구

임우조,황재호 釜慶大學校 1996 釜慶大學校 論文集 Vol.1 No.2

Cavitation is a hydrodynamic phenomenon which results in the formation and collapse of vapour bubbles in a liquid. The stresses produced when the bubbles collapse are considerable and severe erosion may occur to any solids in the vicinity. Cavitation damage is common in ship propellers, pump impellers and in the lubricating or cooling liquids of a vibrating machine such as a diesel engine. Both rotating disc and venturi devices are used to produce cavitation in the laboratory but the most convenient and commonly used devices are based on ultrasonic transducers and there is now a considerable amount of information on the cavitation erosion of materials. In this study, cavitation damage was investigated by using the piezoelectric vibrator with 20 kHz, 24㎛ to cavity generation apparatus. In order to investigate the reliablity for the cavitation erosion-corrosion test apparatus, the cavitation bubble group of test water was carefully measured with respect to test time. The photographs of the cavitation regimes were taken with a high speed camera arrangement by which the cavitation phenomena were studied. It is worth noticing in the vibratory cavitation apparatus that the cavitation bubble group does not fluctuate with test time. The result was ascertained by high speed photographs, which indicated uniform cavitation bubble group with test time.

SUS 304鋼의 SCC 傳播特性에 關 한 硏究

林祐助 釜山水産大學校 1984 釜山水産大學 硏究報告 Vol.24 No.2

定變位引長試驗機를 利用하여 SUS 304 鋼의 SCC 傳播特性을 여러가지 Mgcl₂溶液 中에서 硏究한 結果 다음과 같은 結論을 얻었다. 1) 용접열 영향부의 SCC 傳播는 모재보다 용접열 사이클로 因한 銳敏化 현상에 의해 빨라진다. 2) 용접열 영향부의 SCC 傳播는 主 균열과 미세 균열로 성장하다가 主균열은 ?? 결핍 영역으로 계속 성장되고 미세 균열은 정지된다. 3) 비등 Mgcl₂溶液의 농도가 30%(wt)以下에서는 SCC 傳播가 크게 둔화된다. 4) 42%(wt) 비등 Mgcl₂溶液에서는 初期 SCC 傳播 速度가 빨라지고 같은 농도에서 온도를 115℃로 낮추면 初期 SCC 傳播 速度가 지연된다. The characteristics of SCC propagation of SUS 304 stainless steel were studied with the specimens of the constant displacement type under the environment of various Mgcl₂ aqueous solutions. Main results obtained as follows; 1) SCC propagation of weld heat affected zone has a rapid growth for phenomenon of sensitizing caused by weld heat cycles than that of base metal. 2) SCC propagation of weld heat affected zone has a growth with main and minute cracks, where main crack is grown in to chromium depleted zone, but minute crack stops growing. 3) SCC propagation has a slow growth when the concentration of Mgcl₂boiling solution is bellow 30%(wt). 4) Initial crack growth rate of SCC is rapidly propagated under 42%(wt) Mgcl₂ boiling solution of 143℃, but slowly propagated under the temperature of 115℃ lower than that of 42%(wt)Mgcl₂boiling solution.

MgCl₂ 溶液中에서 SUS 304 鋼 鎔接部의 SCC억제에 관한 연구

임우조,권오봉 釜山水産大學校 1986 釜山水産大學 硏究報告 Vol.26 No.1-2

SUS 304 鋼 鎔接部에 대해 여러가지 濃度의 비등 염화 마그네슘 溶液中에서 SCC 억제를 위한 방법으로서 電氣防蝕法을 실시하여, 一定負荷에서 濃度 條件에 따른 限界 防融電流密度를 究明하였다. 중요한 結果를 要約하면 다음과 같다. 1) SCC 억제를 위한 限界 防融電流密度 以下로 防蝕할 때 용접열 영향부의 龜裂初期 潛伏時間은 모재보다 용접열 사이클로 인한 銳敏化 및 軟化 현상에 의해 빨라진다. 2) 일정한 防蝕電流密度下에서 용접열 영향부의 SCC 억제는 MgCl溶液의 限界濃度에 의해 제어될 수 있다. 3) 용접열 영향부의 限界防融電流密度는 MgCl₂溶液의 濃度에 비례해서 증가한다. The anti-stress corrosion cracking method by current density of cathodic protection was studied for stress corrosion cracking of SUS 304 stainless steel weldments in the environment of various MgCl₂boiling solution(wt%). Main results obtained are as follows: 1) Under the conditions below the critical current density of cathodic protection for anti-stress corrosion cracking, the latent time of crack initiation of weld heat affected zone occurs more rapidly than that of base metal because of the phenomenon of sensitizing and softening caused by weld heat cycles. 2) Under the constant current density of cathodic protection, the anti-stress corrosion cracking of weld heat affected zone can be controlled by critical concentration of MgCl₂solution. 3) The critical current density of cathodic protection of weld heat affected zone increases in proportion to concentration of MgCl₂solution.

應力과 캐비테이션 下에서의 應力腐蝕 擧動에 관한 硏究

황재호,임우재,안석환 釜山水産大學校 1994 釜山水産大學 硏究報告 Vol.34 No.1

In this paper, stress corrosion cracking behavior, and stress corrosion cracking behavior under cavitation-erosion of water injection were investigated. Main result obtained were as follows 1) The weight loss of stress corrosion under stress is less susceptive than that of stress corrosion under stress and cavitation environment. 2) Cracking growth rate of stress corrosion under stress and cavitation is faster than that of stress corrosion under stress. 3) Corrosion potential of stress corrosion under stress and cavitation is less noble than that of stress corrosion under stress. And corrosion current density under stress and cavitation is higher than that of stress corrosion under stress.

船舶용 알루미늄合金材의 腐蝕疲勞龜裂 傳播特性에 미치는 腐蝕傳立의 影響

朴炳學,李鐘樂,曺義一,林祐助 여수대학교 1990 論文集 Vol.4 No.-

Recently, with the tendency of more lightening, high-strength and high-speed in the marine industries such as marine structures, ships and chemical plants, it is rapidly enlarged the use of AL-Alloy and there occurs much interest in the study of corrosion fatigue crack characteristics. Those ships were encountered the corrosion fatigue fracture because of the repeated stress by ship vibration and wave on the voyage under the marine environmentes. In this paper, the occurance of corrosion fatigue crack and the propagation behavior of the 5086-H112 Al-Alloy was tetsted by use of a rotary bending tester and was investigated, on condition of changing corrosion potential (-540, -762, -781 and -794mv/SCE) and air. The experimental constants of Paris'rule was examined in the various corrosion potential, and the enfluence of load and corrosion affected with the crack growth rate was compared with. The retardation effect of corrosion fatigue crack propagation in E=-794mv(SCE) was quantitatively studied.

The Effect of Temperature on Stress Corrosion Cracking of Al Brass under Flow

Lim, Uh Joh,Jeong, Hae Kyoo 한국부식방식학회 2003 Corrosion Science and Technology Vol.2 No.3

The effect of temperature on stress corrosion cracking of Al-brass used in vessel heat exchanger tube was studied in 3.5% NaCl + 0.1% NH₄OH solution. The SCC test using a CDT(constant displacement test) and the specimens using a SEN(single edge notched) specimens. For setting the environment similar to working environment of a heat exchanger, the specimens was immersed in solution and solution llow onto the specimens were performed. The results are as follows : The latent time of stress corrosion crack occurrence gets shorter, as the temperature gets higher. Dezincification phase showed around the crack occupy wider range, as the temperature gets higher. Zn composition falls under 4% at the dezincifiction area.

Study on the Cavitation Damage of Cupronickel(70/30) Tube for Gas Absorption Refrigeration Machine

Lim, Uh-Joh,Jeong, Ki-Cheol,Yun, Byoung-Du The Korean Society of Marine Engineering 2004 한국마린엔지니어링학회지 Vol.28 No.2

The use of gas absorption refrigeration machine has considerably increased because of the shortage of the electric power in the summer and the regulation of freon refrigerant. Gas absorption refrigeration machine consists of a condenser, a heat exchanger. supplying pipes, a radiator etc, This system is likely to be corroded by acid. dissolved oxygen and gases, Cavitation erosion-corrosion by flow velocity of cooling water may happen in absorption refrigeration machine. In these cases. erosion and corrosion occur simultaneously. Then, it makes a serious damage with synergy effect. Therefore, this paper was studied on the cavitation damage of cupronickel(70/30) tube for gas absorption refrigeration machine, In the $30^{\circ}C$ tap water, linear polarization test and anodic polarization test were carried out for copper(C1220T-OL) and cupronickel(70/30) tube. Also, cavitation erosion-corrosion behavior of cupronickel (70/30) tube was considered, The main results are as following: (1) In the linear test, the corrosion current density of cupronickel(70/30) is higher than that of copper. (2) The erosion-corrosion rate of cupronickel(70/30) displayed later tendency than that of copper by vibratory cavitation in cooling water. (3) In cooling water, the progress mechanism of erosion-corrosion rate of copper and cupronickel(70/30) follows a pattern of incubation, acceleration, attenuation and a steady state period.

Study on the Characteristics of Intergranular Stress Corrosion Cracking for Alloy 600

Uh-Joh Lim,Sung-Soo Kang,Gi-Chul Jeong,Byung-Du Yun 한국마린엔지니어링학회 2001 International Conference on Marine Engineering Vol.- No.-