• 제목/요약/키워드: Cast Iron

검색결과 691건 처리시간 0.023초

鑄鐵에 있어서의 黑鉛球狀化機構에 關한 硏究 (1) (Study on the Spheroidizing Mechanism of Graphite in Cast iron (part 1))

  • 최형섭;장지영
    • 대한화학회지
    • /
    • 제7권1호
    • /
    • pp.51-57
    • /
    • 1963
  • It is well known that the graphite flakes become spherulite, when a suitable amount of nodulizing element, such as cerium or magnesium, is added to the cast iron. The change of graphite from flake to nodular shape improves not only the tensile strength but the ductility as well. However, the mechanism of spheroidization of graphite in cast iron has not yet been clearly understood, and various theories proposed by a number of investigators were such that it may be due to the special nucleation effect, prevention of flake formation by the adsorption of magnesium vapour on the graphite surface or file surface free energy difference between plain graphite and magnesium-adsorbed graphite. Regardless of the speculations of spheroidizing mechanism of the graphite in the cast iron, the final phenomenon comes to the conclusion that it may be due to the lack of wettability between graphite and iron matrix. In order to collaborate this fact through an experimental method, the authors have constructed a vacuum arc furnace for the wettability measurement as its first step. Our study and experiments were then directed to the comparison of the wettability between iron and graphite on the two cases (namely, the one where magnesium was preliminarily coated on the graphite surface and the other not coated), by means of contact angle measurements. The result was such that a significant difference of the contact angles has been shown between the above two cases. indicating the spheroidization of graphite which might have resulted from the lack of wettability between magnesium-adsorbed graphite and iron matrix.

  • PDF

An Electrochemical Evaluation on the Corrosion of Weld Zone in Cold Arc Welding of the Cast Iron

  • Moon, Kyung Man;Kim, Jin Gyeong;Lee, Myung Hoon;Kim, Ki Joon
    • Corrosion Science and Technology
    • /
    • 제7권2호
    • /
    • pp.134-137
    • /
    • 2008
  • Cold arc welding of cast iron has been widely used with repair welding of metal structures. However its welding is often resulted in the galvanic corrosion between weld metal zone and heat affected zone(HAZ) due to increasing of hardness. In this study, corrosion properties such as hardness, corrosion potential, surface microstructures, and variation of corrosion current density of welding zone with parameters of used electrodes for cast iron welding were investigated with an electrochemical evaluation. Hardness of HAZ showed the highest value compared to other welding zone regardless of kinds of used electrodes for cast iron welding. And its corrosion potential was also shifted to more negative direction than other welding zone. In addition, corrosion current density of WM in polarization curves was qualitatively smaller than that of HAZ. Therefore galvanic corrosion may be apparently observed at HAZ. However galvanic corrosion may be somewhat controlled by using an optimum welding electrode.

삽입금속을 사용한 구상흑연주철과 2024 알루미늄합금의 마찰압접에 관한 연구 (Friction Welding of Spheroidal Graphite Cast Iron and 2024 Aluminium Alloys using Insert Metal)

  • 김창규;김치옥;김광일
    • 한국해양공학회지
    • /
    • 제17권5호
    • /
    • pp.76-81
    • /
    • 2003
  • Friction welding of GCD45 spheroidal graphite cast iron and 2024 aluminum alloy has been studied, especially in terms of the joint faces and strength of friction welding. For appropriate results of the friction welding of GCD45 graphite cast iron and 2024 aluminum alloy, an insert of A1050 pure aluminum metal was used. The joint strength of the A1050 pure aluminum insert approached the maximum strength of 165.7Mpa, compared to 128MPa for the joint between GCD45 graphite cast iron and A1050 pure aluminum without the insert metal. Maximum strength, 165.7Mpa, was possible for the following optimum conditions: 20MPa for the friction pressure, P1, 60MPa for the upsetting pressure, P2, 1 second for the friction time, t1, 3000rpm for the rotation, N, and 0.3 seconds for the brake time, tB.

글로우 방전/방출분광분석법에 의한 주철시료의 분석 (Analysis of Cast Iron by Glow Discharge Emission Spectrometry)

  • 조경행;우진춘;한명섭
    • 분석과학
    • /
    • 제6권3호
    • /
    • pp.297-305
    • /
    • 1993
  • 글로우 방전 방출원을 다색화장치에 연결시켜 개발된 글로우방전/방출분광법으로 탄소의 농도가 수 퍼센트에 이르러 스파크방출분광법으로서는 분석이 곤란한 주철시료를 분석하고 정확성을 검토하고자 하였다. 알곤가스 압력, 전압, 방전시간 등 glow discharge lamp(GDL)의 방전조건을 최적화시키고 이 조건에서 두 종류의 주철 표준시료(BAS, LECO)에 대해 원소별 방출 복사선의 세기와 농도의 상관관계를 조사하였다. Mn, Si, P, S 등 대부분 원소의 검정곡선이 양호한 직선성을 보여 주었고 탄소의 경우에는 표준시료의 종류에 따라 절편과 기울기값이 미소하게 계통적인 차이를 나타내었다.

  • PDF

구상흑연주철재의 화상해석에 의한 흑연의 극치통계 평가 (Evaluation of Statistical distribution of extreme values of Graphite in Ductile Cast Iron by Image Analyzer)

  • 윤명진
    • 한국기계가공학회지
    • /
    • 제9권6호
    • /
    • pp.71-77
    • /
    • 2010
  • Although the problems of defects and nonmetallic inclusion in metal fatigue are very complicated, it is particularly important to view these problems from the perspective that defects and inclusions are virtually equivalent to small cracks. This concept will help one to understand various fatigue phenomena caused by Ductile Cast Iron. For different ferrite-pearlite matrix structure, containing more than 90% spheroidal ratio of graphite, GCD 45-3, GCD 50, GCD 60 series and 70%, 80%, 90% spheroidal ratio of graphite, GCD 40, GCD 45-1, GCD 45-2 series, this paper has carried out image analyzer, estimated maximum and mean size of graphite, investigated correlation. It was concluded as follows. (1) A good quality of Ductile cast iron using in this experiment, the graphite was separated well. The effect of the interaction by graphite was verified by microscopic observation and by fracture mechanics investigation in surface, interior of the specimen. (2)${\sqrt{area}}_{max}$ of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of ${\sqrt{area}}$ may be used as a guide line for the control of inclusion size in the steel making processes.

가스분무 공정에 의한 과공정 Al-Si 합금 분말 압출재의 마모 거동 (Wear Behaviors of Gas Atomized and Extruded Hypereutectic Al-Si Alloys)

  • 진형호;남기영;김용진;박용호;윤석영
    • 한국분말재료학회지
    • /
    • 제13권4호
    • /
    • pp.250-255
    • /
    • 2006
  • Wear behaviors of gas atomized and extruded Al-Si alloys were investigated using the dry sliding wear apparatus. The wear tests were conducted on Al-Si alloy discs against cast iron pins and vice versa at constant load of 10N with different sliding speed of 0.1, 0.3, 0.5m/s. In the case of Al-Si alloy discs slid against the cast iron pins, the wear rate slightly increased with increasing the sliding speed due to the abrasive wear occurred between Al-Si alloy discs and cast iron pins. Conversely, in the case of cast iron discs against Al-Si alloy pins, the wear rate decreased with increasing the sliding speed up to 0.3m/s. However, the wear rate increased with increasing the sliding speed from 0.3m/s to 0.5m/s. It could be due to adhesive wear behavior and abrasive wear behavior_between cast iron discs and Al-Si alloy pins.

주철과 Fe-Mn-Al강 이종금속 용접부의 조직변화에 관한 연구 (A study on the microstructure change during the welding of a cast iron with a Fe-Mn-Al steel powder)

  • 김경중;서정현
    • Journal of Welding and Joining
    • /
    • 제8권4호
    • /
    • pp.35-45
    • /
    • 1990
  • Casting are widely used nodays as complicated and diversified forming materials due to its superior castability. However the welding of cast iron has not been accompaniced satisfactory resulting in an microstructure change happened in the heat affected zone (HAZ), especially the graphite are formed and shaped consecutively in the area and it has great impact on the crack occuring and growth together with martensite forming in this area. It case of gray cast iron welding, it is required for pre-heat treatment or specific welding consumables to restrain forming the martensite in the HAZ. In this study, by applying the plasma surface overlaid welding. Fe-Mn-Al steel powder has been used for improvement of anti-crackability in the HAZ and much attention has been paid to establish the overlaid welding method for gray cast iron so that optimum welding conditions may prevent the cracking. With our experiments, we have found that to prevent defects which may occur in the HAZ, the overlaid welding technique for gray cast iron has been developed.

  • PDF

오스템퍼 처리(處理)한 구상흑연주철(球狀黑鉛鑄鐵)의 강인화(强靭化)에 관(關)한 연구(硏究)(1) (The Study on the Strength and Toughness of Austempered Ductile Cast Iron)

  • 이영기;김석원;김동건;이방식
    • 한국주조공학회지
    • /
    • 제10권2호
    • /
    • pp.144-153
    • /
    • 1990
  • Ductile cast iron has good ductility and toughness, for the graphite morphology is spheroidal. It has been reported that the strengthening and toughening of the ductile cast iron was resulted from the modification of matrix structure by the heat treatment or the addition of alloying elements. In this study, effects of various special heat treatments (cyclic heat treatment and intermediate heat treatment) and Ni addition on the toughness and strength of the austempered ductile cast iron were studied. The results obtained from this study were as follows : 1. The amount of fine pearlite was increased with the Ni content and the number of cycle in cyclic heat treatment. 2. When the specimens treated and not by special heat treatment at 820 was austempered, in the former the austenite was formed on grain boundary entirely, but in the latter on grain boundary partially. 3. The impact energy was decreased with the Ni content, because the coarisen austenite pools formed with the Ni content was transformed into martensite during quenching. 4. The mechanical properties of austempered ductile cast iron containing 2%Ni treated cyclic heat treatment(5 cycles)was very excellent in handness 99(HRB), impact energy 12(kg-m) maximum fracture load 1500(kg-f).

  • PDF

원심주조법에 의한 주철-Babbitt Metal 복합관 제조에 관한 연구 (A Study on the Fabrication of Cast Iron-Babbitt Metal Composite Pipes by Centrifugal Casting Process)

  • 이충도;강춘식
    • 한국주조공학회지
    • /
    • 제13권1호
    • /
    • pp.42-49
    • /
    • 1993
  • Conventional manufacturing process for cast iron-babbitt metal composite is complicate and bimetallic bonding by centrifugal casting is also difficult because their melting point is largely different and nonmetallic inclusion exists on outer shell. This study is aiming to simplify multistage process by adding Cu-powder as insert metals during cast iron solidification. The variables on fabrication of composite pipe are mold rotating speed and inner surface temperature of outer metal. The optimum temperature range for fusion bonding between cast iron and Cu-layer was $1100^{\circ}C-1140^{\circ}C$ in case of mold rotating speed was 700rpm. When the inner surface of Cu-layer was at $900^{\circ}C$, the value of interfacial hardness between Cu-layer and babbitt metal were higher than Cu-matrix by forming diffusion layer, interfacial products between Cu-layer and babbitt metal are proved to be $Cu_6Sn_5({\eta})$by XRD.

  • PDF

회주철 프레스 금형에 대한 경화육성 자동 MIG 용접시 균열 및 기공방지 기법의 개발 (The development of prevention technique for crack and porosity occured during hardening overlay auto MIG welding for press die of gray cast iron)

  • 유광선;황재련;김덕환;김병훈;황지선;조상명
    • 대한용접접합학회:학술대회논문집
    • /
    • 대한용접접합학회 2005년도 추계학술발표대회 개요집
    • /
    • pp.114-116
    • /
    • 2005
  • There are some problems when weld gray cast iron which is used well in automobile industry with auto MIG welding. the problems are followed like this 1) Occurrence of porosity and hardening organization. 2) Occurrence of crack due to lower elongation of gray cast iron when restraint stress works on. 3) Occurrence of porosity and unstable bead shape due to unstable arc under low current MIG welding.. especially there is a restraint on chemical composition of weld metal because the weldment demands more than 570Hv hardness. so it is hard to use Fe-Ni wire to prevent cracks occured on weldment and new welding method is needed to resolve that problems. This study shows how to prevent porosity and cracks occurring when weld gray cast iron trimming die and shows a new welding method for press die of gray cast iron

  • PDF