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

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Effects of Atmospheric Pressure Microwave Plasma on Surface of SUS304 Stainless Steel

  • Shin, H.K.;Kwon, H.C.;Kang, S.K.;Kim, H.Y.;Lee, J.K.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.268-268
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    • 2012
  • Atmospheric pressure microwave induced plasmas are used to excite and ionize chemical species for elemental analysis, for plasma reforming, and for plasma surface treatment. Microwave plasma differs significantly from other plasmas and has several interesting properties. For example, the electron density is higher in microwave plasma than in radio-frequency (RF) or direct current (DC) plasma. Several types of radical species with high density are generated under high electron density, so the reactivity of microwave plasma is expected to be very high [1]. Therefore, useful applications of atmospheric pressure microwave plasmas are expected. The surface characteristics of SUS304 stainless steel are investigated before and after surface modification by microwave plasma under atmospheric pressure conditions. The plasma device was operated by power sources with microwave frequency. We used a device based on a coaxial transmission line resonator (CTLR). The atmospheric pressure plasma jet (APPJ) in the case of microwave frequency (880 MHz) used Ar as plasma gas [2]. Typical microwave Pw was 3-10 W. To determine the optimal processing conditions, the surface treatment experiments were performed using various values of Pw (3-10 W), treatment time (5-120 s), and ratios of mixture gas (hydrogen peroxide). Torch-to-sample distance was fixed at the plasma edge point. Plasma treatment of a stainless steel plate significantly affected the wettability, contact angle (CA), and free energy (mJ/$m^2$) of the SUS304 surface. CA and ${\gamma}$ were analyzed. The optimal surface modification parameters to modify were a power of 10 W, a treatment time of 45 s, and a hydrogen peroxide content of 0.6 wt% [3]. Under these processing conditions, a CA of just $9.8^{\circ}$ was obtained. As CA decreased, wettability increased; i.e. the surface changed from hydrophobic to hydrophilic. From these results, 10 W power and 45 s treatment time are the best values to minimize CA and maximize ${\gamma}$.

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BICOMPATIBILITY OF BICOMTALS IN RABBIT BONE (임플란트 생체금속들과 골조직간의 생체적합도에 관한 연구)

  • Han, Chong-Hyun;Hoe, Seong-Joo;Chung, Chong-Pyong;Ku, Young;Rhyu, In-Chul;Choi, Yong-Chang
    • The Journal of Korean Academy of Prosthodontics
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    • v.35 no.3
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    • pp.557-565
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    • 1997
  • Screw-shaped implants of commercially pure (c.p.) titanium, c.p. niobium, c.p. zirconium, and stainless steel(Sus 304) were inserted in the rabbit tibial bone over 12 weeks of follow-up. New developed torque gauge instrument was used to evaluate the implant holding power and a image analysis program coupled to a microscope was used for histomorphometry. The three best consecutive threads of each implant were measured. Quantitative analyses at 12 weeks revealed a partial bone contact to the four kinds investigated metals. There were no obvious adverse tissue reactions to any of the biomaterials. At 12 weeks the average removal torques for titanium, niobium and zirconium were better than that needed for Sus 304 screws, on the other hand high score of bony contact ratio of titanium and niobium were showed in comparison to those of zirconium and Sus 304. There was no significant differences in the amount of interfacial bone of zirconium and Sus 304 whereas there was significant difference in the torque forces of niobium and Sus 304. Three months after implant insertion, the average removal torque was 6.64 Ncm for the titanium, 6.57 Ncm for the niobium, 6.38 Ncm for the zirconium, and 4.25 Ncm for the Sus 304. On average bone contacts there were 51.24% in the titanium, 48.19% in the niobium, 31.79% in the zirconium, 23.54% in the Sus 304. Biocompatibility of the titanium, niobium and zirconium was acceptable level in comparison to the Sus 304.

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Buckling and postbuckling behavior of solid superelastic shape memory alloy shafts

  • Rahman, Muhammad Ashiqur;Qiu, Jinhao;Tani, Junji
    • Structural Engineering and Mechanics
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    • v.23 no.4
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    • pp.339-352
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    • 2006
  • Observing the unique stress-strain curves of the superelastic shape memory alloy (SMA) in tension and compression, the primary intention of this study is to investigate the behavior of the shafts made of the same material, under torsional loading-unloading cycles for large angle of twist. Experiments have been performed for the superelastic SMA shafts with different unsupported lengths and angles of twist and the results are compared with those of stainless steel (SUS304) shafts under similar test conditions. As expected for the superelastic SMA, the residual strains are small enough after each cycle and consequently, the hysteresis under loading-reverse loading is much narrower than that for the SUS304. For large angle of twists, the torsional strength of the superelastic SMA increases nonlinearly and exceeds that of SUS304. Most interestingly, the slender solid superelastic SMA shafts are found to buckle when acted upon torsion for large angle of twist.

The Sliding Wear Behavior of Inconel 600 Mated with SUS 304 (SUS 304에 대한 Inconel 600의 Sliding 마모거동)

  • Kim, Hun;Choi, Jong-Hyun;Kim, Jun-Ki;Park, Ki-Sung;Kim, Seung-Tae;Kim, Seon-Jin
    • Korean Journal of Materials Research
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    • v.11 no.10
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    • pp.841-845
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    • 2001
  • The steam generator tubes of power plant damaged by sliding wear due to flow-induced motion of foreign object. Amount of wear have been predicted by Achard's wear equation until now. However, there are large error and low reliability, because this equation regards wear coefficient(k) as constant. The sliding wears tests have been performed at room temperature to examine parameters of wear (wear distance, contact stress). The steam generator tube material for wear test is used Inconel 600 and foreign object material is used 304 austenite stainless steel. The sliding wear tests show that the amount of wear is not linearly proportional to the wear distance(for 374 austenite stainless steel). According to experimental result, wear coefficient is not constant k but function k(s) of wear distance. The newly modified wear predictive equation V=k(s)F have small error and high reliability.

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Comparison of Welding Characteristics of Austenitic 304 Stainless Steel and SM45C Using a Continuous Wave Nd:YAG Laser (오스테나이트계 스테인리스강과 SM45C의 연속파형 Nd:YAG 레이저 용접특성비교)

  • 유영태;오용석;노경보;임기건
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.3
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    • pp.58-67
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    • 2003
  • Welding characteristics of austienite 304 stainless and SM45C using a continuous wave Nd:YAG laser n experimentally investigated Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much Inter than those involved in conventional welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameter such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar and plates, etc. The Nd:YAG laser welding process is one of the most advanced manufacturing technologies owing to its high speed and penetration. This paper describes the weld ability of SM45C carbon steel for machine structural use by Nd:YAG laser. The follow conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power.

TRIBOLOGICAL PROPERTIES OF DLC FILMS SLIDING AGAINST DIFFERENT STEELS

  • Suzuki, M.;Tanaka, A,
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.173-174
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    • 2002
  • To study the effects of mating materials on the tribological properties of DLC films. we used a ball-on-plate reciprocating friction tester in dry air and mating materials of martensite stainless steel (hardened, annealed SUS440C), austenite stainless steels (SUS304), and bearing steel (hardened, annealed SUJ2). At a light load of 0.6 N, the friction coefficient always exceeded ${\mu}>0.3$. Tribological properties of DLC film were still excellent above 0.6 N, except in sliding against annealed SUJ2. Analysis using micro-laser Raman spectroscopy showed that the difference between annealed SUJ2 and others materials appears mainly due to structural change in film.

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An evaluation of Fatigue Crack Propagation Behaviors on Cyclic Overload Test (반복과대하중에 의한 피로파괴거동의 고찰)

  • 김용수;신근하;강동명;김병석
    • Journal of the Korean Society of Safety
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    • v.7 no.2
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    • pp.47-56
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    • 1992
  • The retardation effect of fatigue crack propagation after cyclic overloading seems to be affected by strain hardening exponent. Namely, for the material with high values of n, the delay effect is found to be severe. We proposed a modified crack retardation equation which may apply the retardation of fatigue crack growth after a cyclic overloading, as (da/dN)'$_{cyc}$=($\mu$n+λ)B $\Delta$ $K^{q}$ /[(1- $R_{eff}$) $K_{cf}$$\Delta$K]. where, $R_{eff}$ is effective stress ratio [=( $K_{min}$-K, os)/( $K_{max}$$K_{res}$)] The constants $\mu$=-0.5 and λ=0.6, and the values are found to be identical for materials such as aluminum (A 1060), steel (SS 34), brass ( $B_{s}$ SIB) and stainless steel (SUS 304) used in this investigation. (SUS 304) used in this investigation.ation.n.n.

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Stretch-Flangeability of Harmonic Structure Material Manufactured by Powder Metallurgy Method (분말야금법으로 제조한 하모닉 구조재료의 신장플랜지 가공성)

  • Yoon, Jae Ik;Lee, Hak Hyeon;Park, Hyung Keun;Ameyama, Kei;Kim, Hyoung Seop
    • Journal of Powder Materials
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    • v.24 no.2
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    • pp.128-132
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    • 2017
  • Harmonic structure materials are materials with a core-shell structure having a shell with a small grain size and a core with a relatively large grain size. They are in the spotlight because their mechanical properties reportedly feature strength similar to that of a sintered powder with a fine grain size and elongation similar to that of a sintered powder with a coarse grain size at the same time. In this study, the tensile properties, microstructure, and stretch-flangeability of harmonic structure SUS304L made using powder metallurgy are investigated to check its suitability for automotive applications. The harmonic powders are made by mechanical milling and sintered using a spark plasma sintering method at 1173 K and a pressure of 50 MPa in a cylindrical die. The sintered powders of SUS304L having harmonic structure (harmonic SUS304L) exhibit excellent tensile properties compared with sintered powders of SUS304L having homogeneous microstructure. In addition, the harmonic SUS304L has excellent stretch-flangeability compared with commercial advanced high-strength steels (AHSSs) at a similar strength grade. Thus, the harmonic SUS304L is more suitable for automotive applications than conventional AHSSs because it exhibits both excellent tensile properties and stretch-flangeability.

A Study on the Strength of Brazed Joint for Automotive EGR Cooler by Heat Treatment Conditions (열처리조건에 의한 자동차용 EGR쿨러의 브레이징부 접합강도에 관한 연구)

  • Lee, Joon;Han, Chang-Suk
    • Journal of the Korean Society for Heat Treatment
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    • v.22 no.4
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    • pp.210-216
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    • 2009
  • Stainless steel EGR cooler of diesel engine is widely used to prevent the corrosion due to the content of sulfur in diesel fuel. The strength of brazed joint between stainless steel materials is very important. It is essential to observe the spreading ratio of the filler metals under the condition of deoxidation or vacuum during heating process. In this experiment, spreading ratio was tested to find the optimum brazing condition for stainless steel using brazing filler metals of FP-613, BNi-2 and BNi-5 on sus304 and sus410. Anti-corrosion tests were also performed on the above filler metals with solution of 5% $H_2SO_4$, 65% $HNO_3$ and 5% $NH_4OH$. Consequently FP-613 has good ability for anti-corrosion with 30% of chromium content compared with other filler metals. The optimum brazing conditions are occurred at $960^{\circ}C$ for 90 min. and at $1090^{\circ}C$ for 50 min. at the same degree of vacuum, $2{\sim}3{\times}10^{-3}$ Torr.

A Study on Fatigue Crack Growth Behavior at a Creep Temperature Region in SUS 304 Stainless Steel (SUS 304 강의 크리프 온도역에 있어서 피로균열성장거동에 관한 연구)

  • 주원식;오세욱;조석수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.3
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    • pp.548-554
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    • 1994
  • The high temperature fatigue crack growth behavior of SUS 304 stainless steel at $550^{\circ}C$ and $650^{\circ}C$ was investigated under various kinds of stress ratio and frequency in sinusoidal waveform on the basis of the non-linear fracture mechanics. The result arranging crack growth rate by modified J-integral J' showed influence of stress ratio and frequency. All the data obtained under the test at $550^{\circ}C$ were plotted within data band of da/dN-${\triangle}J_f$ relationship for cycle-dependent crack growth. On the basis of static creep and cycle-dependent data band; both time- and cycle-dependent crack growth behavior was observed under loading conditions at $650^{\circ}C$, but cycle-dependent crack growth behavior predominantly appeared and time-dependent crack growth behaviour was little observed under loading conditions at $550^{\circ}C$. Fractographic examinations for fracture surface indicated that the fracture mode was generally transgranular. The stripes were found on fracture surface and each stripe was accompanied by a crack tip blunting and an abrupt increase in the load-point displacement. The $J'_{an}$ had a validity in case of $650^{\circ}C, but scarcely had it in case of $550^{\circ}C$.