• Title/Summary/Keyword: stainless steel(SUS 304)

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A Study on the Initiation and Growth Behaviors of Surface Crack in a Type 304 Stainless Steel at Room Temperature (SUS 304鋼 의 常溫下 表面피勞균열 의 發생.成長 擧動 에 관한 硏究)

  • 서창민;김규남
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.3
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    • pp.195-200
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    • 1984
  • In-plane tension fatigue tests(R=0.1) were carried out to investigate the initiation and growth behaviors of very small surface fatigue cracks on smooth unnotched surfaces of type 304 stainless steel at room temperature. The present paper deals with the unification of two approaches to the analysis of fatigue: the one approach is based on fracture mechanics concept and the other on low-cycle fatigue concept. The results are;(1)Maximum crack length, 2 $a_{max}$, initiated at a very small surface scratch not exceeding 20 .mu.m which can exist on the surface after buffing. And the density of small surface crack is remarkably low compared to that of mild steel. (2) The growth rate, d(2a)/dN, of very small fatigue cracks can be represented by one straight line as a function of either stress intensity factor range, .DELTA. $K_{I}$ or cyclic total strain intensity factor range, .DELTA. $K_{\epsilon}$$_{I}$/, for various values of the nominal stress range.e.e.e.e.

Practical Experiences with Corrosion Protection of Water Intake Gates in Mekong River

  • Phong, Truong Hong;Tru, Nguyen Nhi;Han, Le Quang
    • Corrosion Science and Technology
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    • v.7 no.6
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    • pp.328-331
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    • 2008
  • Corrosion behaviour of water intake gate steel structures with different protective measures was investigated. Five material alternatives were taken for investigation, including: imported and recycled stainless steel, carbon steel with hot zinc spraying, painting and composite coatings. Results of corrosion rate for carbon steel, SUS 304, hot zinc spray coats in three water systems of Mekong river basin (saline, blackish and fresh) were also presented. Corrosion rate of carbon steel decreased with decreasing salinity in the investigated water environments. Meanwhile, these values for zinc coated steel, behaved by another way. Environmental data for these systems were filed and discussed in relation with corrosion characteristics. Method of Life Cycle Assessment (LCA) was applied in materials selection for water intake gate construction. From point of Life Cycle Cost (LCA) the following ranking was obtained: Zinc sprayed steel < Recycled stainless steel < Composite coated steel < Painting steel < SUS 304 From investigated results, hot zinc spray coating has been applied as protective measure for steel structures of water intake systems in Mekong river basin.

A study on fatigue crack growth with loading waveform and analysis method for all loading waveform at elevated temperature in SUS 304 stainless steel (SUS 304강의 하중파형에 따른 고온피로균열전파속도 및 전체하중파형의 평가방법의 연구)

  • 이상록;이학주;허정원;임만배
    • Journal of Ocean Engineering and Technology
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    • v.6 no.1
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    • pp.122-130
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    • 1992
  • The effect of loading waveform on elevated temperature low-cycle fatigue crack growth behavior in a SUS 304 stainless steel have been investigated under symmetrical trangular (fast-fast), trapezoidal and asymmetrical(fast-slow, slow-fast) waveforms at 650.deg. C. It was found that the crack growth rate in fast-slow loading waveform appeared to be higher a little and the crack growth rate in slow-fast loading waveform much higer than that in fast-fast loading waveform, and difference in crack growth rate between fast-show and slow-fast waveforms nearly didn't appear in the region of da/dN>10/sup -2/ The crack growth rate in the trapezoidal loading waveform with t/sub h/=500sec appeared to be faster than that in slow(500sec)-fast(1sec). In addition, parameter modified J-integral could be considered as useful parameter for fatigue crack growth rate in all waveforms. The result obtained are as follow. da/dN=4.91*10/sup -3/ (.DELTA. J/sub c/)/sup 0.565/.

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Influence of Brazing Temperature on Strength and Structure of SUS304 Stainless Steel Brazed System with BNi-2 Filler Metal : Fundamental Study on Brazeability with Ni-Based Filler Metal(II) (BNi-2계 삽입금속에 의한 SUS304 스테인리스강 접합체의 강도와 조직에 미치는 브레이징 온도의 영향 : Ni기 삽입금속에 의한 브레이징 접합성의 기초적 검토(II))

  • Lee, Yong-Won;Kim, Jong-Hoon
    • Korean Journal of Materials Research
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    • v.17 no.3
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    • pp.179-183
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    • 2007
  • A plate heat exchanger (PHE) normally uses vacuum brazing technology for connecting plates and fins. However, the reliability of high temperature brazing, especially with nickel-based filler metals containing boron the formation of brittle intermetallic compounds (IMCs) in brazed joints is of major concern. since they considerably degrade the mechanical properties. This research was examined the vacuum brazing of commercially SUS304 stainless steel with BNi-2 (Ni-Cr-B-Si) filler metal, and discussed to determine the influence of brazing temperatures on the microstructure and mechanical strength of brazed joints. In the metallographic analysis it is observed that considerable large area of Cr-B intermetallic compound phases at the brazing layer and the brazing tensile strength is related to removal of this brittle phase greatly. The mechanical properties of brazing layer could be stabilized through increasing the brazing temperature over $100^{\circ}C$ more than melting temperature of filler metals, and diffusing enough the brittle intermetallic compound formed in the brazing layer to the base metal.

A Study on the Characteristic of Weld Joint and Tensile Fracture of SUS304 and Cu High-Speed Dissimilar Lap Welds by Single Mode Fiber Laser (싱글모드 파이버 레이저를 이용한 SUS304와 Cu의 고속 겹치기 용접에서 접합부 및 인장시험 파단부의 특성에 관한 연구)

  • Lee, Su-Jin;Kim, Jong-Do;Katayama, Seiji
    • Journal of Welding and Joining
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    • v.32 no.6
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    • pp.56-63
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    • 2014
  • To develop and understand dissimilar metals joining of Stainless steel and Copper, ultra-high speed laser lap welding was studied using single mode fiber laser in this study. SUS304 and Cu have large differences in materials properties, and Cu and Fe have no intermetallic compounds by typical binary phase of Cu and Fe system. In this study, ultra-high speed lap welds of SUS304 and Cu dissimilar metals using single-mode fiber laser was generated, and weldability of the weld fusion zone was evaluated using a tensile shear test. To understand the phenomenon of tensile shear load, weld fusion zone of interface weld area and fracture parts after tensile shear test were observed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis system. And it was confirmed that Cu was easily melting and penetrating in the grain boundaries of SUS304 because of low melting temperature. And high thermal conductivity of copper occurred dissipate heat energy rapidly. These properties cause the solidification cracking in weld zone.

An Investigation of Stress Corrosion Cracking Characteristics of SUS 304 Stainless Steel Weldments (SUS 304鋼 熔接部 의 SCC特性 에 관한 硏究)

  • 김영식;임우조
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.6
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    • pp.569-575
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    • 1984
  • The characteristics of the stress corrosion cracking of SUS 304 stainless steel weldments were studied with the speciments of the constant displacement type under the environment of 42% MgC $l_{2}$ boiled solution (143.+.-.2.deg.C). The susceptibility of initiation and propagation of the stress corrosion crack was quantitatively inspected in the weld metal, heat affected zone and heat affected zone with including the reinforcement shape, respectively. Also, those susceptibility were discussed in connection with the change of mechanical and microstructural characteristics caused by heating cycle of welding. Main results obtained are as follows: (1)Stress corrosion cracking is easiest to initiate and propagate in the heat affected zone of weldment. (2)The susceptibility of stress corrosion cracking of the weldment is largely improved by eliminating the reinforcement part of the weld bead. (3)The dominant factor of the cracking susceptibility of the heat affected zone appeared to be the phenomenon of softening and sensitizing caused by welding heat cycle. (4)Under the low loading conditions, the behavior of stress corrosion cracking of the SUS 304 steel weldment is largely influenced by the pitting phenomenon in the front region of the main crack.

Evaluation of Cutting Characteristics for Hot-Drilling of Stainless Steel (스테인리스강의 고온드릴 작업시 절삭성 평가)

  • 이민국;심재형;백인환
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.287-290
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    • 2002
  • Stainless steel used widely in various fields of industry have the characteristics of difficulty-to-cut. This difficulty comes from its peculiarity, for example work hardening, vibration, etc. And these peculiarity on the cutting process have an effect on tool wear or life shortness of tools. To solve these problems several method have been developed. Hot-machining is one way of these method. when a material is heated, organization of material is soften. So cutting process becomes easy. When such a hot-machining method applies on drilling process and then heated material is processed, cutting force is less than usual drilling process cutting force. In this paper, cutting force is compared heated SUS 304 with usual SUS 304. And shape of chips is also compared.

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Study on Characteristics of Corrosion Fatigue Crack Growh Rate of SUS 304 Stainlss Steel (SUS 304강의 부식피로균열 운전속도 특성에 관한 연구)

  • 임우조;김부안
    • Journal of Ocean Engineering and Technology
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    • v.1 no.2
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    • pp.93-100
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    • 1987
  • Corrosion fatigue cracking of the austenitic stainless steel(bese metal & heat affected zone by TIG weld) was studied experimentally under the environments of various specific resistance and air. The characteristics of corrosion fatigue crack growth rate and the environmental constants of paris' rule were investigated for SUS 304 weldments in the various specific resistance. The influences of stress intensity factor range and corrosion on the crack growth rate were compared. The characteristics of corrosion fatigue cracking for the weldments were inspected from mechanical, electrochemical and microstructural point of view. Main results obtained are as follows: 1) As the specific resistance decreases, the environmental constant C of paris'rule increases(hence the corrosion fatigue crack growth rate is rapid), but the environmental constant m decreases, so the effect of corrosion to the crack growth rate is more susceptible than thet of stress intensity factor range. 2) As the stress intensity factor range decreases, the corrosion fatigue crack growth rate of heat affected zone is more susceptible than that of the base metal. 3) The corrosion fatigue crack growth rate of the heat affected zone is more rapid than that of the base metal, because of the phenomenon of softening and the less noble potential coused by wedlding heat cycle. 4) The corrosion fatigue cracking of SUS 304 weldment appears transgranular fracture.

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Wear Behavior of SUS304 Stainless Steels in Corrosive Environment (부식 환경에서 SUS304 스테인레스 강의 마모 거동)

  • Lee Kwang-Jin;Yoon Sang-Don;Koo Young-Pil;Kim Hyung-Ja
    • Tribology and Lubricants
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    • v.20 no.2
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    • pp.91-96
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    • 2004
  • Wear behavior of self-mated stainless steels in NaCl solution has been investigated. The experiment was done in the corrosive liquid of which NaCl concentration of $0\~3\%$ and temperature of $15\~90^{\circ}C$. Two kinds of wear type were observed: one is 'severe wear' type which shows gradually increasing wear volume with increasing sliding distances, the other is 'mild wear' type which shows change of wear rate from high value to low at transition distance. The specific wear rate in severe wear type was not sensitive to the liquid temperature and concentration of NaCl but stable at value of $1\times10^{-3}\;mm^3$ approximately.