Stainless steel의 용접부의 인성에 미치는 합금원소의 영향

허재근 서울産業大學校 1999 논문집 Vol.50 No.2

Measurements of vTrs and absorbed energy of stainless steel and its welds by V-notch charpy Impact test were carried out in the temperature range from 80 to 140℃ in order to clarify the effects of alloying elements on the toughness of the steel and welds. The specimens of welds were prepared from 3.2㎜ hot rolled and annealed plate by TIG(tongsten inert gas) meet run with I-grooved joint without fller. The toughness of the specimen was evaluated from the values obtained from the charpy impact test. The main results obtained are as follows; 1)The transition curves of the base metal and welds are remarkably shifted to lower temperatures with decreasing the content of carbon and nitrogen and adding the proper amounts of titanium and manganese. 2)The ductile-brittle transition temperature lower to a large extent with adding the proper contents of titanium and also making the structure of steel become a single phase of ferrite. 3)Manganese addition strengthens the weld metal by solution-hardening and simultaneously disperses the precipitation of flaky chromium carbides of M7C3 and M23C6, and consequently improves the toughness of the welds remarkably.

Lath Martensite의 組織構成

許在根 서울産業大學校 1984 논문집 Vol.20 No.1

Structural characteristics of lath martensite were investigated indetail using Fe-C alloys plain carbon steels with carbon of up to 0.8%,18% Ni maraging steel and Fe-0.2%C alloys with an addition of about 1% of Mn Si, Cr, or M. The construction of lath martensite structure changes with carbon content. The packet regions are clearly formed within a prior austenite grain at lower carbon content. but they are not observed in the range of 0.5-0.8%C. The block regions within a packet are observed only in the steels below about 0.3%C. Structure of lath martensite in the 18% Ni maraging steel is characterized by the block region which are well-developed and completely partitions a packet region. where the blocks in the low carbon steels are not well-developed regions. A packet size gradually decreases with increase in carbon in carbon conternt up to 0 .4%C and repidly decreases in the 0.6 and 0.8%c. A linear relation exists between the austenite grain size and packet size in Fe-0.2%C alloy and 18 Ni maraging steel. the increase in block with of maraging steel with increasing austenite grain size is very small. Alloying elements within about 1% have little effect on the construction of Lath martensite and the packet size

高Mn鋼에서 各種元素添加와 炭化物析出에 對한 硏究

許在根 서울産業大學校 1983 논문집 Vol.19 No.1

Some Hadfield Steels with 1%Si 2% Al 0.8% Mo 4% Cr were studied mainly by micrography on isothermal carbide Precipitation after Solution treatment. Isothermal Precipitation diagrams for all steels were determined as c-carve fundamentally similar to that of standard Hadfield steel. By addition of 1%Si, the carbide Precipitation in steel was little affected, But the temperature range in which pearlitic constituent(PC) appeared was slightly extended. By addition of 2% Al, the grain boundary carbide precipitation in high temperature rang was accelerated, but the tramstormation in ti PC was retarded and its temperature range was limited in a Slightly narrow range. Moreover, matrix precipitation of carbide in high temperature range was disturbed remarkably by addition of Al. By addition of carbide forming elements such as Mo and Cr the precipitation of carbide was accelerated especially in high temperature range, and the precipitation temperature range was extended to higher temperature.

Cu-A1 二元合金의 A1 添加量에 �x른 機械的 性質에 關한 硏究

許在根 大田工業專門大學 1979 論文集 Vol.25 No.-

Mechanical properties were investigated in many types of AL added to Al- br-onze by Amsler, Rockwell Hardness tester and Charpy impact tester. 1. Tensile strength and elongation of the AL-bronze shows best tensile strength in 10 percent Al content and elongation of the 8 percent Al content was best but In 10 percent up Al content was very brittle. 2. Hardness of the Al-bronze was rapidly increased In 8 percent Al content up.

冷間壓延法에 依한 Aluminum Clad鋼의 接着機構에 關한 硏究

許在根 서울産業大學校 1985 논문집 Vol.22 No.1

A number of studies on bonding mechanism of clad metals by cold rolling have been reported, but a definite conclusion of the bonding mechanism has not yet been recognized. In cold clad practice, it can be thought that the factors affecting the bondability may be kind of metals, surface condition, thickness ratio of metals, temperature, relative ship, and so on. Several factors affecting the bond shear strengh of aluminium clad steel by cold rolling were examined. Furthere, the temperature of the bond during rolling was measured by I.C. thermo-couple. As the result, an average temperature of about 650℃ in 0.05 sec. was obtained. From these facts it may be suggested that the bonding mechanism by cold rolling is mutual fusion of metals at contact part under high pressure and high deformation by frictional heat caused by relative ship of metals.

靑銅合金의 機械的 性質에 關한 硏究

許在根 서울産業大學校 1980 논문집 Vol.13 No.1

Recently, many active research On the mechanical behavior Consed by the Vibration have been Carried Out the Cu-Sn alloy, and it is Very Seldom the dlata of bell with Cu- Sn alloy. In this Paper the author's Concern has been Concentrated On the mechanical Properties, the results Obtained in this Study are summerised as follows. 1. Tensile Strength of A (Cu80%, Sn20%) is 20.1kg/㎟,and tensile Strength of B(cu85%, Sn15%) is 21.5kg/㎟,therefore the Strength of B is higher about 7% than A. 2. Hardness of A is higher about 22% than B. 3. The absorbed energy of A and B are Similarly on impact test. 4. The α Solid Solution A and B are Changed δ Phase, and brittleness ofδ Phase on A are appeared higher than B.

흑심가단주철의 취성에 대한 연구

허재근 서울産業大學校 1992 논문집 Vol.36 No.1

An investigation has been made of the effect of cooling rate form both 450℃ and 650℃ and also the effect of treatments consisting of various combination of heating rate, holding temperature and cooling rate on the shift of transition temperature of blackheart malleableiorn by impact test. IMA analysis has also carried out on the fracture surface of specimens cooled from 450℃ under the various cooling conditions. The results obtained are as follows : (1) Holding at 650℃ or slow cooling from 450℃ shifts the transition temperature to lower temperatures. (2) Quenching from 450℃ increases the tendency of embrittlement. (3) Any heat treatment have no the transsition temperature when cooled from 650℃ after 0.5h. holding. (4) The influence of cooling fate from 650℃ to room temperature on the embrittlement of blackheart malleable iron is almost the same as that in the temperature range from 650℃ to 450℃ (5) IMA analysis on the fracture surface of blackheat malleable iron cooled from 450℃ with various cooling rate shows that the larger the cooling rate is, the higher the phosphorus concentration on the fracture surface becomes.

高張力鋼 熔接部에 대한 機械的 性質에 關한 硏究

許在根 서울産業大學校 1982 논문집 Vol.17 No.1

Recently high Strength Steel has been produced in Korea, This study aims aat a research on the mechanical characteristic and microscopic structure of the weld zone of the high strength steel when welding it by means of a lowhydrogen-type welding rod. Some of the signiticant findings are:tensile strength in weld zone by 10kg/㎟ more than basemetal:L-260(60㎏/㎟ type welding rod) was Superior to L-200(50㎏/㎟ type welding rod) in terms of its strength: hardness value increased more in weld zone than in basemetals in particular hardness value in heat effected zone was the highest: impact value increased in weld zone about 2 or 3㎏-m more than in base metal: the microscopic structure of weld zone was finer than that of base metal. On the basis of thesefacts, this study concluded: the weld Zone of the high strength steel produced in korea increased in its tencile strength, yield strength, hardness Value, and impact value than base metal: the microsopic structure of the weld zone of the high strength steel is finer than that of base metal. Therefore, in case of using the high strength steel for making a structure three important factors should be attended to in its constrution: first the choise of a welding rod: Second the size of weld zone (X and Y direction) third, the structure of weld zone.

W 섬유강화 Al합금기지복합제의 열cycle에 따른 계면거동에 관한 연구

허재근,김정태,현창용,김용석,김석윤 ( J . G . Huh,J . T . Kim,Ch . Y . Hyun,Y . S . Kim,S . Y . Kim ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.3

The reaction layer formed at interface between matrix and fiber has significant effects on the mechanical properties and behaviors of deformation in FRM. In this study, the mechanical properties and interfacial behaviors according to surface finishing on the fibers and according to heat treatment in FRM were investigated. FRM was fibricated by diffusion bonding method. In W/Al alloy composite and W/Al composite, W of which was coated with WO₃, the heat treatment was carried out thermal cycling method from 373K to 673K. In W/Al composite, W of which was coated with WO₃, growth of interface layer was hardly occured in spite of the increasing various thermal cycles. It was exhibited that oxidized W/Al composite were higher strength than non-oxidezed W/Al composite with the increasing thermal cycles. The compounds of fiber/matrix interface were analyzed into WAl_(12), WAl_5 and AlWO₃, respectivly. Therfore the interfacial compounds of fiber/matrix seriously affected the mechanical properties and behaviors of deformation in FRM.

Boron섬유강화 Al합금기지 복합재료의 제조와 파괴거동에 관한 연구

허재근 서울産業大學校 1992 논문집 Vol.35 No.1

The effect of the fabrication condions on the mechanical properties of the composites were investigated at various bonding times and various temperatures. A1/B composites were fabricated by vacuum hot press. The highest tensile strengths of B/A1 composites were obtained at 773K for 30 min irrespective of the matrix used. The composites fabricated at the optimum condions were had fractured at various temperatures and times and tested fro their mechanical properties changes. The observation of the interface with optical microscopy and SEM. The fabrication condition and the heat treatment did not significantly affect the fracture surface of the composites.