• 제목/요약/키워드: Casting Defects

검색결과 189건 처리시간 0.02초

반용융 단조품의 제조 (Manufacturing of Product by Semi-Solid Forging)

  • 박형진;강충길;김병민;최재찬
    • 한국정밀공학회지
    • /
    • 제16권6호
    • /
    • pp.45-51
    • /
    • 1999
  • The semi-solid forging is a new forging technology in which the billet is heated to the semi-solid state coexisting liquid and solid phase for making globular microstructure and subsequently formed. As the semi-solid forging is compared with conventional casting such as die casting and squeeze casting for the characteristics of its process, the product without inner defects such as gas porosity and segregation can be obtained and its microstructure is globular grain. Simutaneously, its mechanical properties are improved by globular microstructure and the lower temperature of the slug causes the cycle time of manufacturing to be shortened and the die life to be lengthened. As it is compared with conventional cold and hot forging, it is possible to minimize the equipment of production owing to a lower forming load and reduce the number of process by a followed treatment for complex shaped product. Therefore it is needed to confirm the quality of a semi-solid forged product by defining its characteristics quantitatively under these advantages. This paper investigates the formability of a master cylinder by its forming variables. And the microstructural characteristics and mechanical property of it is also studied.

  • PDF

연속주조법에 의한 Sn-38%Pb 공정합금의 초소성특성 (A Study on the Superplastic Characteristics of Sn-38%Pb Eutectic Alloy Produced by Continuous Casting Process)

  • 송태석;조형호;최재하;지태구;김명한
    • 한국주조공학회지
    • /
    • 제17권3호
    • /
    • pp.252-257
    • /
    • 1997
  • The 8 mm dia: Sn-38%Pb eutectic alloy rods were produced by use of the horizontal continuous casting process with the heated mold and chill cast process. The cast rods were rolled into 2.0${\sim}$0.5 mm thick plates and structural and mechanical properties were examined. The results revealed that the plates produced by the continuous casting process with the heated mold show much higher superplasticity at ambient temperature (1550% elongation at 0.5mm thick plate and 0.5mm/min strain rate) than the plates procuced by chill cast process (630% elongation). Such a high superplasticity of the continuous cast plates is due to the high-quality plates free from any inside and surface defects with fine and uniform distribution of eutectic phases.

  • PDF

파이버 레이저를 이용한 이종 마그네슘 합금의 용접성에 관한 연구 (The Weldability of the Dissimilar Magnesium Alloy Welded by Fiber Laser)

  • 김종도;김영식;송무근;이정한
    • Journal of Welding and Joining
    • /
    • 제31권2호
    • /
    • pp.63-68
    • /
    • 2013
  • Magnesium alloys have gained increased attention in recent years as the structural materials, because of their attractive properties such as good specific strength, excellent sound damping capability. However, to expand their applications, a reliable joining process is absolutely necessary. In this study, a CW fiber laser was used to investigate the lap weldability of sand casting and wrought magnesium alloys. The effect of defocused distance on lap weldability was examined, and it was found that spatters always generated at the around focused distance because of the high power density of the laser beam. Thus, defocused distance was required to obtain sound welds. In addition, the application of fillet welding was evaluated for minimizing the affect of sand casting magnesium alloy that have relatively poor weldability. As a result of this study, we could confirm good weldability without weld defects.

A356 합금 시편의 수축공 결함형상에 대한 피로해석용 형상 모델링 방법 (On Shrinkage Cavities Shape Modeling for Fatigue Simulation of A356 Alloy Specimen)

  • 곽시영;조인성
    • 한국주조공학회지
    • /
    • 제39권1호
    • /
    • pp.1-6
    • /
    • 2019
  • During the casting process, it is possible to minimize shrinkage and blowholes by modifying the casting design. However, it is impossible to eliminate these factors completely. Therefore, mechanical design engineers apply a sufficient safety factor owing to the possibility of insufficient performances of the cast products. In this paper, prediction method of the fatigue life of cast products containing shrinkage is conducted by using CT (computed tomography) and the SSM (shape simplification method), and additional fatigue analyses are carried out. The analysis results are then compared to results from actual experiments on samples with shrinkage defects. It is found to be that the considering actual shrinkage in cast products by means of stress and fatigue analyses is more accurate and effective. It is also considered that the proposed hot spot method provides us a good tool to predict the fatigue lifes of cast product.

Numerical and Experimental Study of Semi-solid A356 Aluminum Alloy in Rheo-Forging process

  • 김현호;강충길
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2009년도 추계학술대회 논문집
    • /
    • pp.371-374
    • /
    • 2009
  • Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D. Samples of metal parts were subsequently fabricated by using hydraulic press machinery.

  • PDF

게이트 형상이 결정입 제어 소재의 미세조직에 미치는 영향 (The Effect of the Gate Shape on the Controlled Material the Microstructure of Grain Size)

  • 정용식;배정운;서판기;강충길
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2004년도 추계학술대회논문집
    • /
    • pp.152-155
    • /
    • 2004
  • In the semi-solid die casting process, the important thing is the flow behaviors of semi-solid material. The flow patterns of semi-solid material can make the defects during die filling. To control of the flow patterns, is very important and difficult. In this paper, the flow behaviors of the semi-solid A356 alloy material during die filling at various die gate shapes has been observed with the grain size controlled material. The effects of the gate shape on the die filling characteristics were investigated. The filling tests in each plunger strokes were experimented, also simulated on the semi-solid material die casting process by MAGMAsofi. According to the filling tests and computer simulation, the effect of the gate shape on liquid segregation had been investigated.

  • PDF

Fabrication of Plasma Electrolytic Oxidation Coatings on Magnesium AZ91D Casting Alloys

  • Lee, Sung-Hyung;Yashiro, Hitoshi;Kure-Chu, Song-Zhu
    • 한국표면공학회지
    • /
    • 제50권6호
    • /
    • pp.432-438
    • /
    • 2017
  • AZ91D casting alloy requires an advanced plasma anodizing processing because large amount of defects are liable to generate during anodization. In this study, plasma electrolytic oxidation (PEO) of AZ91D Mg alloy was conducted by the application of either constant voltage or current using a pulse mode and its effects on pore formation, surface roughness and corrosion resistance were investigated. The PEO films showed a three-layer structure. The PEO film thickness was found to increase linearly with voltage. The surface roughness, Ra, ranged between $0.2{\mu}m$ and $0.3{\mu}m$. The corrosion resistance increased from RN 3.5 to 9.5 by the PEO treatment when evaluated according to the 72 hour salt spray test. The PEO-treated surface exhibited higher pitting potential than the raw material.

AI 기반의 주조 공정 파라미터 최적화를 통한 알고리즘 개선 (Algorithm Improvement Through AI-Based Casting Process Parameter Optimization)

  • 심현;최서영;김현욱
    • 한국전자통신학회논문지
    • /
    • 제18권3호
    • /
    • pp.441-448
    • /
    • 2023
  • 제조 공정 데이터에 있어 주조 공정은 가장 중요한 공정이면서 높은 불량률의 원인을 발생시키는 공정이다. 주조 공정의 품질관리는 생산성과 품질평가의 핵심 요소라 할 수 있다. 본 연구에서는 공정 데이터를 통한 요인 분석, 상관 분석, 회귀 분석 결과를 기반으로 최적화 된 머신러닝 모델 알고리즘을 개발한다. 이를 적용한 주조공정을 통해서 불량률을 줄이고 스마트 팩토리의 데이터 적합성을 검증하고자 한다.

3D-ESPI 시스템을 이용하여 결정된 응력집중계수가 피로수명에 미치는 영향에 관한 연구 (A Study on the Effect of Stress Concentration Factor Determined by 3D-ESPI System on the Fatigue Life)

  • 김경수;심천식
    • 한국해양공학회지
    • /
    • 제16권1호
    • /
    • pp.46-51
    • /
    • 2002
  • Fatigue life estimation by the theoretical stress concentration factors are, in general, considerably different from test results. And in calculating stress concentration factor, it is very difficult to consider actual geometry and material property which are the notch shapes, imperfections or defects of materials such as porosities inclusions and casting defects, etc. Therefore, the paper deals with the experimental method to find out the more exact stress concentration factors by measuring the strain distributions on each specimen by 3D-ESPI(Electronic Speckle Pattern Interferometry) System. Then the fatigue lives are compared between theoretical calculations using stress concentration factors determined by 3D-ESPI system and fatigue test results.

X-ray 실시간 관찰에 의한 알루미늄 합금의 응고 결함 관찰 (In-situ X-Ray Observation of Shrinkage Defect of the Aluminum Alloy Castings)

  • 조인성;김정인;임채호
    • 한국주조공학회지
    • /
    • 제30권5호
    • /
    • pp.174-178
    • /
    • 2010
  • In the present study, in-situ real-time observation with an X-ray radioscopic facility was carried out on pure aluminum and aluminum alloy solidification. The three kinds of aluminum alloys, such as pure aluminum, Al-8.5%Si alloy, commercial A356 (AC4C) alloys, were used in the present study. The formations of the shrinkage defects in the castings were visualized and different formation phenomena for different aluminum alloys were investigated.