• 제목/요약/키워드: Cast-Forging

검색결과 60건 처리시간 0.024초

고대 한반도 주조철기 열처리 기술에 대한 고찰 (A Study of Cast Ironware Heat Treatment Technique in Ancient Korea)

  • 최영민
    • 헤리티지:역사와 과학
    • /
    • 제53권1호
    • /
    • pp.168-183
    • /
    • 2020
  • 기원전 5세기부터 중국에서는 주조철기의 사용을 늘리기 위해 주조철기 특유의 취성(脆 性)을 제거하려 노력해 왔다. 그중 한 가지는 주조철기를 생산한 다음 별도의 가마에서 풀림열처리를 하는 기술이다. 이 기술은 조직 내 탄소를 응집하거나 제거해, 주조철기의 취성을 제거하고 단조(鍛造)를 가능하게 만드는 것이다. 풀림열처리 기술의 실체를 명확히 하기 위해 현재의 제철 기술 및 중국·일본의 연구 성과를 바탕으로 한반도 출토 고대 주조철기 가운데, 풀림열처리 기술이 확인된 가단주철제 주조철기를 검토하였다. 그 결과 원삼국시대 이전까지 가단주철제 주조철기는 모두 외부로부터 수입된 것으로 추정된다. 또한 일본 이시가미신궁에 소장 중인 칠지도가 한반도에서 제작된 것으로 본다면, 4세기에 들어서야 백제에서는 풀림열처리 기술을 확보했을 가능성이 있다. 하지만 당시에는 괴련철을 중심으로 철 생산이 이루어졌으며, 괴련철을 정련한 괴련강을 소재로 다량의 단조철기가 제작되었다. 또한 기존의 주조철기 중 주조괭이를 제외한 대부분의 주조철기가 단조철기로 대체되었다. 따라서 삼국시대까지 풀림열처리 기술은 많이 사용되지 못하였다. 하지만 통일신라시대에 들어서 철 생산 및 유통의 지역 거점인 장안리 유적에서 확인될 정도로 기술이 확산된 것을 확인하였다.

김포 양촌유적 출토 원삼국시대 철부에 적용된 제작기술 검토 (Study on the Manufacturing Technology Applied on Iron Axes of Proto-Three Kingdoms excavated from Yangchon, Gimpo)

  • 유재은;이재성
    • 보존과학회지
    • /
    • 제29권4호
    • /
    • pp.367-378
    • /
    • 2013
  • 원삼국시대에 속하는 경기도 김포시 양촌유적에서 출토된 단조철부 5점과 주조철부 1점을 대상으로 미세조직 관찰과 비금속개재물 분석을 실시하였다. 단조품에 사용된 소재는 순철에 가까운 소재와 저탄소강이 사용되었고 성형 후 1점에만 담금질을 하였다. 주조품은 주철을 탈탄시킨 미세조직이 보여 주철탈탄 제강법이 적용된 것을 확인하였다. 비금속개재물 분석결과 철부는 고체저온환원법으로 제련하여 생산된 괴련철을 두드려서 제작하였다. FeO 함량이 $SiO_2$에 비해 비교적 높게 나타나 제련 시 노의 온도가 환원에 충분하지 못해 Fe의 회수율이 적었던 것으로 보이며 이 과정에서 광물에 포함된 K, P, Mg, Mn, Ti 등 불순물이 혼입되었다. Ca 함량이 높게 검출되는 곳이 있어 일부는 조제제로 석회물질을 넣었던 것으로 추정된다.

회주철의 마찰용접 특성에 관한 연구 - 입열량 이론식을 중심으로 - (Friction Weldability of Grey Cast Iron - by the Concept of Friction Weld Heat Input Parameter -)

  • 정호신;방국수
    • Journal of Welding and Joining
    • /
    • 제32권3호
    • /
    • pp.95-101
    • /
    • 2014
  • Joining of grey cast iron by fusion welding has much difficulties for its extremely low ductility and low toughness because of the flake form of the graphite. And the brittle microstructure, i.e. ledeburite may be formed during fusion welding by its rapid cooling rates. By these kinds of welding problem, preheat and post heat treatment temperature must be increased to avoid weld crack or welding problems. In order to avoid these fusion welding problem, friction welding of cast iron was carried out for improving joint soundness, establishing friction welding variables. There is no factor for evaluating friction weldability in continuous drive type friction welding. In this point of view, this study proposed the parameters for calculating friction weld heat input. The results obtained are as follows ; 1. There was a close relationship between tensile strength and flash appearance of friction welded joint. 2. Tensile strength was decreased and flash was severely oxidized as increasing frictional heating time. 3. As increased forging pressure $P_2$, flash had a large crack and tensile strength was decreased. 4. As powdered graphite by rotational frictional force induced flat surface and hindered plastic flow of metal, tensile strength of welded joint was decreased. 5. Heat input for continuous drive type friction welding could be calculated by the factors of $P_1$, $P_2$ and upset distance(${\delta}$).

대형 로터의 자유단조공정에서 기공압착 예측을 위한 유한요소해석 (FE Analysis for the Prediction of Void Closure on the Free Forging Process of a Large Rotor)

  • 이경진;배원병;김동권;김영득;조종래
    • 소성∙가공
    • /
    • 제16권2호
    • /
    • pp.126-131
    • /
    • 2007
  • Voids in a large rotor are formed in solidification process of a cast ingot. The voids have to be eliminated from the rotor by a forming process, because they would became stress-intensity factors which suddenly fracture the rotor in the operation. Previous studies on void-elimination of a large rotor have mainly focused on finding the process variables affecting the void-closure. But the study on the amount of void closure in a large rotor has been very rare. This study was performed to obtain an equation which predicts the amount of void-closure in a forging process of a large rotor and to evaluate the availability of the void-closure equation through finite element analyses. Firstly, 2D FE analysis was carried out to find effects of time integral of hydrostatic stress and effective strain on void volume rate of a large rotor in the upsetting process for various diameters and shapes of void, and material temperature. From the 2D FE analysis, we found that effective strain was suitable for predicting the void-closure of a large rotor, because there was a constant relationship between void volume rate and effective strain. And a void-closure equation was proposed fur predicting void-closure of a large rotor in the upsetting process. Finally, ken the 3D FE analysis, the proposed void-closure equation was verified to be useful for upsetting and cogging processes.

반연속주조된 대형 블룸에서 발생하는 거시편석 및 석출물 거동 (Behavior of Macrosegregation and Precipitation Developed in Semi-continuously Cast Large Bloom)

  • 김혜주;이형록;김경아;이주동;오경식;권상흠;김동규
    • 한국주조공학회지
    • /
    • 제39권1호
    • /
    • pp.7-13
    • /
    • 2019
  • Few studies of large blooms over 700 mm thick among those used for the forging of raw materials have been reported. The cooling rate difference between the surface and the center of a large bloom is large, and the degradation of the mechanical properties is likely in cases involving excessively coarse precipitates resulted from the slow cooling rate of a large bloom after casting. Therefore, a schematic investigation of the growth behaviors of precipitates while varying their locations in blooms is necessary. The dissolution behaviors of precipitates were investigated by simulating a reheating process during which the bloom is heated to a high temperature. The segregation behavior of the as-cast large bloom was also investigated. Reheating specimens were obtained after an isothermal heat treatment at $1150^{\circ}C$ with various holding times to simulate the reheating process, with the samples undergoing a subsequent water quenching step. The precipitates were extracted using an electrolytic extractor and a particle size analysis was conducted with the aid of SEM, EDS, and TEM. In the present work, Al oxide, MnS and Nb carbide were mainly observed.

삼국시대(三國時代) 철기유물(鐵器遺物)의 제작기술(製作技術) 연구(硏究) (Iron Technologies of the Three Kingdoms Period in Korea)

  • 정광용
    • 헤리티지:역사와 과학
    • /
    • 제35권
    • /
    • pp.138-158
    • /
    • 2002
  • To compare and analyze technical system related to manufacturing of ironware during the period of the Three Kingdoms, an analysis was conducted on the minute system of metalwork, as study objects, of the remains of the Mt. Wolpyeong fortress wall in Daejeon in the period of capital during the era of the Three Kingdoms in the 5th century, the Sanwol-ri remains in the 6th century in Gunsan and the remains of ironware excavated from the great ancient tomb of Hwangnam of the Silla dynasty in the 5th century. The result of analysis shows that in the most of the casting products, the minute system of white cast iron were contained. While the iron part of decarbonization was in the system by casting as white cast iron in the central part, on the surface layer it was turned out that comparatively uniform 100% pearlite system of about 1~2mm degree was existing. The part of pearlite on the surface layer was caused by decarbonization, which appears in all the parts of blade front end and handle. Therefore, it was found that the iron part of decarbonization was manufactured by casting, and then was processed at the high temperature by decarbonization. For the products of forging, after processing the products on the basis of pure iron for materials, they manufactured the ironware that raises the strength by carbonizing that keeps carbon infiltrated on the necessary part, by the method of black smith welding that add pure iron to steel, or by varying the method of heat processing onto the part required of strength. Though limited, we could understand that the technical systems for manufacturing skill of ironware in the areas of Baekje and Silla were different each other. In the technical system for Hwangnam great ancient tomb in the Silla area, it is found that they had raised the strength on the necessary part by applying the steelmaking method of carbonizing in the last stage of production of products, in the meantime in Baekje area, it appears that they had produced steel in advance in the first stage of production of the products, and used the produced steel only to the necessary part.

경주 양북면 봉길리 유적출토 청동검의 제작기술에 관한 연구 (Bronze Technology Observed in a Bronze Dagger Excavated from Bongili in Yangboongmyon, Gyeongju)

  • 주진옥;박장식
    • 보존과학회지
    • /
    • 제26권2호
    • /
    • pp.143-148
    • /
    • 2010
  • 본 연구에서는 경주 봉길리에서 출토된 청동검 한 점의 미세조직과 화학성분을 분석하였다. 그 결과 이 동검에는 납이 포함되지 않은 주석함량 10%의 청동합금이 사용되었으며 제작과정에 두드림 공정이 적용된 것으로 밝혀졌다. 지금까지 보고된 한반도 출토 동검의 절대다수가 납 청동을 주조하여 제작된 것임을 고려할 때 무연청동에 두드림 공정을 적용하였다는 점에서 본 동검은 다른 것들과 구별된다. 이 동검은 고고학적 가치가 큰 희귀한 자료로서 고대 경주지방에 독특한 청동기 기술을 구사하는 집단의 존재 가능성을 시사한다.

고대와 현대 방짜수저의 균열발생 원인분석 (Failure Analysis of Cracks in Ancient and Modern Bronze Spoons)

  • 최병학;이범규;심종헌;고형순;조남철;이재성;박경균;김유찬
    • 한국재료학회지
    • /
    • 제26권10호
    • /
    • pp.528-534
    • /
    • 2016
  • The aim of this paper is to consider the effect of the manufacturing processes on corrosion and centerline cracking of ancient bronze spoons. The ancient bronze spoons in question were made by several steps of forging, in reheated condition with cast ingots. The manufacturing method is similar to that of the modern spoons. The investigations include observations from light and scanning electron microscopes of the microstructure in terms of the crack propagation. Cracks in the centerline are caused by solute segregation in the center-line region; this solute is solidified in the final stage of bronze spoon manufacture. Centerline cracking is also caused by ${\alpha}$ phase segregation, accompanied by forged overlapping along the longitudinal direction of the spoons. A vertical stripe with cracks along the centerline of the spoon's width is formed by folding in the wrought process. The overlapping area causes crack propagation with severe corrosion on the spoon surfaces over a period of a thousand years. The failure mechanisms of ancient bronze spoons may be similar to that of modern spoons, and the estimation of the failure mechanisms of ancient spoons can be appropriate to determine failure causes for such modern spoons.

매트릭스(matrix)형 냉간금형강의 기계적 특성에 미치는 NbC 탄화물 첨가의 영향 (Effect of NbC Carbide Addition on Mechanical Properties of Matrix-Type Cold-Work Tool Steel)

  • 강전연;김호영;손동민;이재진;윤효윤;이태호;박성준;박순근
    • 열처리공학회지
    • /
    • 제28권5호
    • /
    • pp.239-249
    • /
    • 2015
  • Various amount of NbC carbide was intentionally formed in a matrix-type cold-work tool steel by controlled amount of Nb and C addition. And the effect of NbC addition on the mechanical properties was investigated. Four alloys with different Nb and C contents were cast by vacuum induction melting, then hot forging and spheroidizing annealing were conducted. The machinability of the annealed specimens was examined with 3 different cutting tools. And tensile tests at room temperature were conducted. After quenching and tempering, hardness and impact toughness were measured, while wear resistance was evaluated by disk-on-plate type wear test. The increasing amount of NbC addition resulted in degraded machinability with increased strength, whereas the absence of NbC also led to poor machinability due to high toughness. After quenching and tempering, the additional NbC improved wear resistance with increasing hardness, whereas it deteriorated impact toughness. Therefore, it could be found that a moderate addition of NbC was desirable for the balanced combination of mechanical properties.

조선시대 족자 장황에 사용된 고리의 재료 및 제작기법 연구 (A Study of Material and Production Technique of Scroll Painting Ring in Joseon)

  • 장연희;윤은영;권윤미;김수연
    • 박물관보존과학
    • /
    • 제16권
    • /
    • pp.56-81
    • /
    • 2015
  • 족자 고리는 끈이나 유소를 고정시켜 걸 수 있도록 하는 장황 부속품으로 형태가 다양하며 여러 금속재를 사용하여 제작되었다. 현재 전통 형식의 고리는 대부분 개장으로 인해 유실되었으며, 일본식 고리를 사용하고 있다. 따라서 본 연구에서는 국립중앙박물관에 소장된 전통 족자 19점을 대상으로 고리의 형태와 제작기법, 성분을 조사하여 옛 형태를 복원해 보고자 하였다. 의궤 내용에서 고리는 원환(圓環), 국화동(菊花童), 배목(排目) 등 고유의 명칭으로 기록되어 있다. 휴대용 엑스선 형광분석기(portable X-ray fluorescence, Artax, Rontec)로 성분을 분석한 결과, 전통 형식의 고리는 황동, 철, 은-구리합금 등 다양한 금속재로 확인되었다. 구리와 아연이 주성분인 황동은 17점 족자 고리에 사용되었다. 전 윤시달 초상(신2339)의 배목에서는 철을 사용하였으며, 주석-납 합금으로 도금하였다. 이서구 초상(신1065)에서는 고리 전체가 은-구리합금으로 제작되었음을 확인하였다. 광학현미경(Leica, M205A)으로 제작 방법을 조사한 결과 원환은 금속봉을 절단한 뒤 둥글게 휘어 만든 유형과 주조로 제작된 유형으로 확인되었다. 배목은 주조한 합금으로 봉재나 판재를 만들고 다시 단조과정을 거쳐 제작하였고, 배목장식은 금속판재를 잘라 형태를 만든 후 축조와 타출기법 등으로 무늬를 새겨 장식하였다.