• Title, Summary, Keyword: Wear

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Sliding Wear Behavior of AISI 52100 Steel with Pearlitic and Bainitic Microstructures (미세조직 변화에 따른 AISI 52100 강의 미끄럼마멸 특성)

  • Yoon, N.;Kim, Y.S.
    • Transactions of Materials Processing
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    • v.20 no.7
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    • pp.479-484
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    • 2011
  • Dry sliding wear behavior of AISI 52100 steel that has a pearlite or bainite microstructure was characterized to explore the effect of microstructure on the wear of the steel. Isothermal heat treatments were employed to obtain the different microstructures. Pin-on-disk type wear tests of the steel disk were performed at loads of 25~125N in air against an alumina ball. Sliding speed and wear distance used were 0.1m/sec and 300m, respectively. Worn surfaces, wear debris and cross-sections of the worn surfaces were examined with SEM to investigate the wear mechanism of the steel. Hardness of the steel was also evaluated. Wear rate of the steel was correlated with the hardness and the microstructure. On the whole, wear resistance increased with an increase in hardness. However, the pearlite microstructure showed superior wear resistance as compared to the bainite microstructure with a similar hardness. The effect of the microstructure on the wear rate was attributed to the morphological differences of the carbide in the microstructure, which was found to have a significant effect on strain hardening during the wear.

Analysis of the Sliding Wear Mechanism of Pure Iron Tested Against Different Counterparts in Various Atmospheres (상대재와 분위기에 따른 순철의 미끄럼 마멸 기구 분석)

  • Koo, B.W.;Gwon, H.W.;Kim, Y.S.
    • Transactions of Materials Processing
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    • v.26 no.6
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    • pp.365-371
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    • 2017
  • During sling wear of a ferrous metal, a surface layer is formed. Its microstructure, constituting phases, and mechanical property are different from those of the original wearing material. Since wear occurs at the layer, it is important to characterize the layer and understand how wear rate changes with different layers. Various layers are formed depending on external wear conditions such as load, sliding speed, counterpart material, and environmental conditions. In this research, sliding wear tests of pure iron were carried out against two different counterparts (AISI 52100 bearing steel and $Al_2O_3$) in the air and in an inert Ar gas atmosphere. Pure iron was employed to exclude other effects from secondary phases in steel on the wear. Wear tests were performed at room temperature. Worn surfaces, wear debris, and cross-sections were analyzed after the test. It was found that these two different counterparts and environments produced diverse layers, resulting in significant changes in wear rate. Against the bearing steel, pure iron showed higher wear rate in an Ar atmosphere due to severe adhesion than that in the air. On the contrary, the iron showed much higher wear rate in the air against $Al_2O_3$. Different layers and wear rates were analyzed and discussed by oxidation, severe plastic deformation, and adhesion at wearing surfaces.

Analysis of Sliding Wear Behavior of Mild Steel According to Hardness of Dissimilar Mating Materials (이종 상대재 경도에 따른 철강재료의 미끄럼 마모 특성 해석)

  • Lee, Han-Young
    • Tribology and Lubricants
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    • v.32 no.6
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    • pp.195-200
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    • 2016
  • This study examines the wear behavior of mild steel pins mated against alloyed tool steel discs in a pin-on-disc type sliding test machine and provides specific clarification regarding the effects of disc hardness on the wear behavior of a mating mild steel pin. The analysis confirms these effects through the observation of differences in the wear rates of the mild steel pins at low sliding speed ranges. These differences occur even though the hardness of the mating disc does not affect the wear characteristic curve patterns for the sliding speeds, regardless of the wear regime. In the running-in wear regime, increasing the hardness of the mating disc results in a decrease in the wear rates of the mild steel pins at low sliding speed ranges. However, in the steady-state wear region, the wear rate of a pin mated against the 42DISC is greater than the wear rate of a pin mated against the 30DISC, which has a lower hardness value. This means that the tribochemical reactivity of the mating disc, which is based on hardness value, influences the wear behavior of mild steel at low sliding speed ranges. In particular, oxides with higher oxygen contents, such as $Fe_2O_3$ oxides, form predominantly on the worn surface of the 42DISC. On the contrary, the wear behavior of mild steel pins at high sliding speed ranges is nearly unaffected by the hardness of the mating disc.

A Study on the Development of Pattern and Design for Pet Dog's Wear (애완견 의상의 패턴과 디자인 개발 연구)

  • Lee, Joo Eun
    • Fashion & Textile Research Journal
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    • v.14 no.5
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    • pp.846-852
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    • 2012
  • Pets (such as dogs) are considered as important as family members, this perspective is due to an aging population and the decreased size of the traditional nuclear family. The pet industry has been growing every year; subsequently, is useful to develop practical patterns and designs appropriate for the body structure and movement of pet dogs. However, studies to develop a new form of pet dog's wear patterns and designs are limited. This study develops a basic pattern that is easily used based on a pet dog's size, designs popular clothing items for pet dogs, and helps in the manufactures of pet dog's wear. The results are as follow: 1) Analyzed categories and popular items of pet dog's wear from the research of the prior studies and on-line pet dog shopping malls; three categories (everyday wear, street wear, and special wear) and six items (T-shirt, one-piece, coat, jumper, and dress, tuxedo). 2) Developed the basic bodice pattern and sleeve pattern after test-wearing and revising the experimental patterns referenced from prior studies. 3) Developed patterns and designs for six popular items based on situation and gender: one-piece (everyday wear), coat (street wear), wedding dress (special wear) for female dogs/T-shirt (everyday wear), hood jumper (street wear), tuxedo (special wear) for male dogs. 4) Developed the previous six items to illustrate the research results of the study.

Wear Simulation of Engine Bearings in the Beginning of Firing Start-up cycle (파이어링 시동 사이클 초기에서의 엔진 베어링 마모 시뮬레이션)

  • Chun, Sang Myung
    • Tribology and Lubricants
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    • v.35 no.4
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    • pp.244-266
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    • 2019
  • The purpose of this study is to estimate the wear volumes of engine journal bearings operating at variable angular velocity of a shaft in the beginning of firing start-up cycle. To do this, first we find the potential region of wear scar on engine journal bearings where the applied bearing load and crank shaft velocity are variable. The potential wear regions are discovered by finding minimum oil film thickness at every crank angle existing below most oil film thickness scaring wear (MOFTSW) obtained based on the concept of the centerline average surface roughness. Then we calculate the wear volume from the wear depth and two wear angles decided by the magnitude of each film thickness lower than MOFTSW at every crank angle. The results show that the expected wear region is located at a few bearing angles after and/or behind the upper center of a big-end bearing and the lower center of a main bearing. And the real wear region is similar to the estimated wear region. Further we find that the wear scar on an engine journal bearing may occur at re-starting time after switch-off of a start motor especially under the condition of high oil temperature.

Study on the Analysis of Wear Phenomena of Ion-Nitrided Steel (이온질화 처리강의 마모현상 분석에 관한 연구)

  • Cho, Kyu-Sik
    • Tribology and Lubricants
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    • v.13 no.1
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    • pp.42-52
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    • 1997
  • This paper deals with wear characteristics of ion-nitrided metal theoretically and experimentally in order to analysis of wear phenomena. Wear tests show that compound layer of ion-nitrided metal reduces wear rate when the applied wear load is mall. However, as th load becomes large, the existence of compound layer tends to increase wear rate. The residual stress at the surface of ion-nitrided metal is measured, and the internal stress distribution is calculated when the normal and tangential forces are applied to the surface of metal. Compressive residual stress is largeest at the compound layer, and decreases as the depth from the surface increases. Calculation shows that the maximum stress exists at a certain depth from the surface when normal and tangential force are applied, and that the larger the wear load is the deeper the location of maximum stress becomes. In the analysis, it is found that under small applied wear load the critical depth, where voids and cracks may be created and propagated, is located at the compound layer, as the adhesive wear, where hardness is an important factor, is created the existence of compound layer reduces the amount of wear. When the load becomes large the critical depth is located below the compound layer, and delamination, which may be explained by surface deformation, crack nucleation and propagation, is created, and the existence of compound layer increases wear rate.

Experimental and Analytical Study on the Die Wear during the Upsetting Processes (업셋팅 금형의 마모 실험 및 해석)

  • 박종남;김태형;강범수;이상용;이정환
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.122-130
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    • 1996
  • During the cold forming, due to high working pressure acting on the die surface, failure mechanics must be considered before die design. One of the main reasons of die failure in industrial application of metal forming technologies is wear. Die wear affects the tolerances of formed parts, metal flow and costs of process etc. The only way to control these failures is to develop methods which allow prediction of die wear and costs of process etc. The only way to control these failures is to develop methods which allow prediction of die wear and which are suited to be used in the design state in order to optimize the process. In this paper, the wear experiments to abtain the wear coefficients and the upsetting processes was accomplished to observe the wear phenomenon during the cold forming process. The analysis of upsetting processes was accomplished to observe the wear phenomenon during the cold forming process. The analysis of upsetting processes was accomplished by the rigid-plastic finite element method. The result from the deformation analysis was used to analyse the die wear during the processes and the predicted die wear profiles were compared with the measured die wear profiles.

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Post-purchase Evaluation on the Maternity Wear on the Current Korean Market by Survey and Wear test

  • Park, Soon-Jee;Lee, Hee-Jung;Suh, Chu-Yeon
    • Journal of Fashion Business
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    • v.11 no.3
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    • pp.15-34
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    • 2007
  • This study was designed to collect a precise information concerning to the preference and evaluations after usage of pregnant Korean woman for the maternity wear bysurvey and wear tests. Through the survey, 212 respondents were asked to answer what type of maternity wear they prefer and what requirements for maternity wear design are important. According to the results of survey, the mostly preferred maternity wear items were pants and one-piece dress. Korean customers for maternity wear usually pay more for the one-piece dress than other items and they also usually put on medium price pants and low-price blouse. Concerning to the purchase criteria, it may be said that design and movability, fit factors are the buying decision criteria of great weight for Korean pregnant women. Special function most desired was thermal insulation, followed by buffer action, electromagnetic shield and quickly water-absorbent and dry property. Preferred maternity wear design details were flat collar, slightly fitted waist and empire style, gather skirt, rubber band waist. Wear test was performed for two kinds of blouse (BL) and one-piece dress (OP), and threekinds of pants (PT), which have different design details respectively. According to the wear test for ready-to-wear maternity garments, the garment which considers well the characteristics of Korean pregnant women body shape earned much higher score no matter of brands or prices. Generally, high-priced national brands received an excellent evaluation in design aspect, but not satisfied with comfort to move.

The Effect of TiN and CrN Coatings on the Fretting Wear of Tubes against Supports in a Nuclear Steam Generators

  • Park, Dong-Shin;Park, Jung-Min;Kim, Jin-Seon;Lee, Young-Ze
    • KSTLE International Journal
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    • v.10 no.1_2
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    • pp.33-36
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    • 2009
  • The nuclear steam generator is composed of a bundle of tubes. The length of these tubes is very long, but their diameter is small. Fluid exists inside of the steam generator and its flow causes vibration, therefore these tubes are supported by anti-vibration bars. The wear damage due to the vibration is known as fretting wear, which should be minimized to ensure the safety of the plants. Research needs to be done about decreasing the amount of fretting wear. Hard coatings have proven to be very effective in reducing the amount of wear. The commercial coatings of TiN and CrN have excellent wear resistance and are used to protect the Inconel tube from fretting wear. The tube-on-flat type tester was used for conducting the fretting wear tests. It was found that the wear amounts of the coated tubes decreased depending on the coating thickness. CrN was found to be very effective in reducing the wear, while the wear amounts were dependent on the coating thickness in the case of TiN and a thick coating of TiN was very effective on wear resistance.

A Study on the Improvement of the Wear Resistance of P-bronze (인청동의 내마모성향상에 대한 연구)

  • Song, Kun;Kwun, Sook-In;Cha, Young-Hyun
    • Tribology and Lubricants
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    • v.4 no.1
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    • pp.56-68
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    • 1988
  • The wear resistance of P-bronze which is widely used as worm gear material was investigated. In order 1o study the effect of additional elements on the wear resistance of Pbronze, the applied load and sliding time were selected as variables, and SCM4, were used as against metal. The addition of Fe improve wear resistance, for it precipities hard Fe$_3$ P phase and the work hardening coefficients are lowered due to decreasing solubility of P. When Fe is added in conventional P-bronze, the alloy is rather sliding than forming wear debris by frictional force during wear test. Experimental results indicated that the wear mechanisms for P-bronze are mainly consisted of abrasive wear due to Beilby layer forming mechanism and adhesive wear due to thermally activated wear mechanism. Moreover, the weight loss is decreased in accordance with increasing load and time. However the rate of wear loss is decreased as the sliding time is increased.