• 제목/요약/키워드: hardness

검색결과 10,295건 처리시간 0.043초

판스프링을 사용한 건식마모실험에서 재료경도에 따른 마모거동 (Wear Behavior as Hardness Difference of Material in the Dry Sliding Wear Tests of Using Leaf-Spring)

  • 김정현
    • 한국공작기계학회논문집
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    • 제17권3호
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    • pp.27-33
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    • 2008
  • It is shown that the rate of wear can be related to 'index of wear intensity' using a leaf-spring in the disc on disk on wear tests. Since both upper and lower specimens have used the same hardness values, equivalent hardness of 'the index of wear intensity' used the mean hardness value of specimens. This index is derived from the external variables of load, sliding speed and the hardness of the sliding pairs. The wear behavior as the hardness of the sliding elements on the dry wear has been investigated using a disc on disc configuration. The materials of the specimens are used as ten kinds along their hardness. Using experimental data, we figured the relationship between wear rate and index of wear intensity. A newly wear equation had been derived the result using a leaf-spring in disc on disc wear system.

로크웰 경도도 순회 비교측정 결과에 대한 분석 (Analysis on the Results of the Rockwell Hardness Round Robin Test)

  • 방건웅;탁내형
    • 열처리공학회지
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    • 제14권5호
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    • pp.275-281
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    • 2001
  • To improve the reliability of hardness test results, Rockwell hardness round robin test was carried out for 10 laboratories. The test condition was the same with the ISO(International Standards Organization) standards. Korea Research Institute of Standards and Science(KRISS) supplied the hardness standard blocks and an indenter to laboratories for the measurement. The participating laboratories measured hardness of the specified areas on the blocks for 6 times with their own indenter as well as common indenter, respectively, and reported the results to KRISS. The result showed that quite large amount of the differences came from the indenter and it is necessary to change indenter with better quality for improved reliability in hardness measurement.

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경도-유효변형률 관계에 관한 유한요소 해석 (Finite Element Analysis for the Relation between Hardness and Effective Strain)

  • 권순구;박준홍
    • 한국산업융합학회 논문집
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    • 제2권2호
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    • pp.125-130
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    • 1999
  • It is already known that hardness value of cold-forged product is in close conjunction with its effective strain. This paper presents the method to predict the relation between effective strains and hardness values by using FE-simulation of hardness test from the conception that hardness indicates resistance to plastic deformation. The results of FE-simulation for the material with pre-strain arc compared with those of experiments of the references to show the feasibility of the proposed method.

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한국산업표준(KS)에 따른 로크웰 경도 시험기의 불확도 산정에 관한 연구 (A Study on the Evaluation of Uncertainty of Rockwell Hardness C Scale According to the Korean Industrial Standards(KS))

  • 방건웅;탁내형
    • 열처리공학회지
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    • 제13권3호
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    • pp.163-169
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    • 2000
  • Recently, uncertainty of hardeness became a major concem for the people working on the laboratory evaluation and accreditation. It is required to indicate uncertainty of hardness tester on the report after calibration. In addition to this, uncertainty of certified hardness reference block is also required to indicate on the certification sheet. Method on the evaluation of uncertainty in hardness measurement is agreed only recently for Rockwell hardness C scale. In this paper, a preliminary calculation of uncertainty based on type B evaluation has been made for hardness testers which satisfies the requirements of Korean Standards. It was found that the tolerance limit of mean value specified in KS should be increased to be compatible with the calculated uncertainty.

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원형핀의 밀리 전방압출에서 녹아웃패드와 압출비가 기계적 성질 변화에 미치는 영향 (Effects of knock-out Pad and Extrusion Ratio on Mechanical Property Changes in Milli-Forward Extrusion of Cylindrical Pin)

  • 심경섭;김용일;이용신;김종호
    • 소성∙가공
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    • 제12권6호
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    • pp.582-587
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    • 2003
  • This paper is concerned with the mechanical property changes of the milli-size products manufactured by forward extrusion processes with square dies. Experiments are carried out with pure aluminum and pure copper billets. Extrusion ratio and knock-out pad are chosen as the important process parameters affecting the changes of mechanical properties such as shear strength and hardness. Shear strength tests with the extruded milli-size pin have shown the strong relation between victors hardness and shear strength in the neck of a stepped pin. As the extrusion ratio increases, the hardness on both the surface and the center line of a pin also increase. It is also noted that the hardness on the surface is a little higher than that on the center. The existence of knock-out pad in extrusion die causes the hardness in the neck of a extruded pin to increase. Finally, the approximated linear relations between shear strength and hardness of a pin are suggested.

니켈쌀파메이트 전주층의 물성과 미세구조 (Study on the Mechanical Properties and Microstructure of Nickel Sulfamate Electroform)

  • 김인곤
    • 한국표면공학회지
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    • 제37권1호
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    • pp.40-48
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    • 2004
  • Hardness and internal stress are very important in nickel electroforming. Nickel sulfamate bath has been widely used in electroforming because of its low internal stress and moderate hardness. Nickel sulfamate bath without chloride was chosen to investigated the effect of plating variable such as temperature, PH, current density and sodium naphthalene trisulfonate as addition agent on the hardness and internal stress. It was found that hardness increased with increasing temperature and decreasing current density and ranged from 150∼310 DPH. The hardness was highest at $55^{\circ}C$ and 10∼40 mA/$\textrm{cm}^2$. The internal stress increased with increasing current density and decreasing temperature. It was minimum at PH 3.0∼3.8. Low internal stress within $\pm$1,500 psi was obtained at both $50^{\circ}C$ and $55^{\circ}C$ in 10-20 mA/$\textrm{cm}^2$. The addition of sodium naphthalene trisulfonate was found to be effective in refine columnar grains thus resulted in decreasing internal stress, increasing hardness and improving brightness.

Effect of Sintering Temperature, Heat Treatment and Tempering on Hardness of SH737-2Cu-0.9C Sintered Samples

  • Anand, S.;Verma, N.;Upadhyaya, A.
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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    • pp.555-556
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    • 2006
  • The study examines hardness pattern of SH737-2Cu-.9C samples transient liquid phase sintered at different temperatures viz. $1120^{\circ}C$, $1180^{\circ}C$ and $1250^{\circ}C$, heat treated by various methods and then tempered at different temperatures. Sintered samples were characterized for density and densification parameter, and austenitized at $900^{\circ}C$, subsequently cooled by four different methods viz. annealing, normalizing, oil and brine quenching. Hardness pattern was found minimum for air cooled and maximum for brine quenched, and samples sintered at $1250^{\circ}C$ had relatively higher hardness. The O.Q and B.Q samples were then tempered at $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$ and $700^{\circ}C$. Hardness pattern typically showed secondary hardness taking place, with maximum around $600^{\circ}C$.

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축임물의 경도에 따른 평판인쇄잉크의 유화량 변화에 관한 연구 (Effect of Hardness of Dampening Solution on Emulsification for Lithography Ink)

  • 조진우;김성빈;오지만
    • 한국인쇄학회지
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    • 제20권1호
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    • pp.123-132
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    • 2002
  • The literature often mentions the hardness of water in dampening solutions as possible source of problem. In most literature describes that the water hardness affects print quality. However water hardness affects not only print quality, but also emulsification of ink and dampening solution. Therefore the purpose of this study was to determine if water hardness actually affects the emulsification rate of dampening solution and ink. And this study for the factors determining the emulsion velocity, we have measured water pick-up and calculated emulsion velocity constant 'k' and activation energy.

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유동응력과 비커스경도의 관계 실험적 연구 (An Experimental Study on the Relation between Flow Stress and Vickers Hardness)

  • 이충호
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 춘계학술대회논문집
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    • pp.65-68
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    • 1997
  • Vickers hardness is defined as indenting force per unit area indented by a pyramid-shaped diamond at the hardness test. It is well known that Vickers hardness has a direct relation with the flow stress of the strain-hardened material. This relation was theoretically investigated and the result was summerized in a form of algebraic equation in the last paper. In the present paper and experimental validation of this theoretical relation is given along with mathematical formulas for conversion of Vickers hardness into the flow stress in the strain-hardened material for practical use.

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유동응력과 비커스경도의 이론적 관계 연구 (A Study on the Theoretical Relation between Flow Stress and Vickers Hardness)

  • 이충호
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 춘계학술대회논문집
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    • pp.69-72
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    • 1997
  • The indentation process in the Vickers hardness test is a kind of controlled local plastic deformation. Vickers hardness is defined as indenting force per unit area indented by a pyramid-shaped diamond at the hardness test. That is a measure of mechanical resistance against indentation of a rigid body into the deformable material. Therefore it is well known that Vickers hardness has a direct relation with the flow stress of the strain-hardened tmaterial. This relation is theoretically investigated and the result is given for use in practice.

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