• Journal of Welding and Joining
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• 제9권1호
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• pp.9-15
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• 1991

국내에서는 1988년 하반기부터 50kg/mm$^{2}$급 TMCP강재가 생산되기 시작하여 국내 조선 업계도 TMCP강재의 사용이 가능하게 되었다. 이에 따라 국내수요가들은 국산 TMCP 강재의 원활한 사용을 위하여 생산자 주관으로 'TMCP강종개발위원회'를 주기적으로 개최하여 국산 TMCP강의 품질 평가와 함께 TMCP강의 단점 등을 여러 측면에서 검토, 보완하고 있다. 본 해설에서는 TMCP강재의 문제점들 중에서 선박용 강재로 사용하고자 할 때 가장 큰 문제점으로 제기되고 있는 절단변형에 대해 기술코자 한다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.6-8
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• 2005

The purpose of this study is to evaluate characteristics of plate forming by flame heating for E and EH36 TMCP steel. The characteristics of interest were heat-formability of TMCP steel and mechanical properties of heated area. For a given dimension, heat-formability of TMCP steel was inferior to that of a conventional steel because TMCP steel required more heating passes and time. Angular distortion and transverse shrinkage of TMCP steel decreased with an increase in line heating speed for given heating conditions. The mechanical properties of TMCP steel after plate forming by flame heating were high enough to satisfy the requirements.

• Journal of Welding and Joining
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• 제17권3호
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• pp.96-101
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• 1999

Microstructures and mechanical properties of weldments were studied for EH36 TMCP higher-strength hull steel with electrogas welding jprocess. In case of a newly designed EH36 TMCP steel for large heat input welding process, the Microstructures of HAZ shows more narrow width of grain coarsed region than that of conventional EH36 TMCP weldments, the amount of acicular ferrite, which is beneficial to impact toughness, increased while the amount of grain-boundary ferrite decreased. Charpy V-notched impact tests show that a newly designed EH36 TMCP steel weldment satisfies all the requirement of specifications, especially at the fusion line +2mm where the conventional EH36 TMCP steel fails to exceed the requirement.

• Journal of Welding and Joining
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• 제6권2호
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• pp.9-18
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• 1988

본 고에서는 가속냉각형 TMCP강재에서 발생되는 연화현상을 정립하고자, 본 저자들의 그간 연구결과와 기존의 연구보고들을 종합적으로 검토하여 연화현상에 미치는 제반 인자들의 영향을 정량화하고자 하였다. 연화현상에 관계되는 인자로는 화학성분이나 강재 두께 등의 강재자체의 내적인자와 용접, 후열처리 등의 외적인자로 나누어 평가하였다. 이를 토대로 시공시 발생되는 가속냉각형 TMCP강재의 강도변화를 예측함으로써 TMCP강재를 보다 효율적으로 중공업분야에 확대적용하고자 한다.

• Journal of Welding and Joining
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• 제16권6호
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• pp.44-51
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• 1998

It is well known that the fine bainitic microstructure obtained by TMCP(thermo-mechanical control process) secures the high toughness of base metal. Besides, TMCP steel is very suitable for high heat input in welding as it has low carbon equivalent. In HAZ, however, the accelerated cooling effect imparted on the matrix by the weld thermal cycles is relieved and thus the weldment of TMCP steel has softening zone which shows low fracture toughness compared with base metal. Therefore, PHWT of weldment is carried out to improve the fracture toughness in weldment of TMCP steel which has softening zone. In this study, the effects of PWHT on the weldment of AH36-TMCP steel are investigated by the small punch (SP) test. From the several results such as SP energy and displacement at room temperature, the behavior of transition curves, the fracture strength at -196$^{\circ}C$, distribution of (DBTT)sp and (DBTT)sp, the PWHT condition of A.C. after 85$0^{\circ}C$-1 sec W.C. was suitable condition for recovering a softening zone of HAZ as welded.

• Journal of Welding and Joining
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• 제15권1호
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• pp.46-54
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• 1997

The object of this paper is to evaluate SCC(stress corrosion cracking) susceptibility for parent metal and bond line region of weld joints which have the various weld heat input condtions in TMCP(thermo-mechanical control process) steel by SP-SSRT(small punch-slow strain rate test) method. And the SCC test results of TMCP steel are compared with those of the conventional HT50 steel which has te almost same tensile strength level like TMCP steel. The loading rate used was $3\times10^{-4}$mm/min and the corrosive environment was synthetic sea water. According to the test results, in the case of parent metal, TMCP steel showed higher SCC susceptibility than HT50 steel because of the high plastic strain level of ferrite microstructure obtained by accelerated cooling. And in the case of bond line, the both TMCP steel and HT50 steel showed low load-displacement behaviors and higher SCC susceptibility above 0.6. These results may be caused by theembrittled martensite structure on HT50 steel and by the coarsened grain and the proeutectoid ferrite structure obtained by the impart of accelerated cooling effect on TMCP steel.

• 한국강구조학회 논문집
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• 제18권3호
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• pp.395-403
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• 2006

최근 건설되는 강교량은 지간의 장대화 및 교량으로서의 기능은 물론이고 외적 조형미, 유지관리, 공사기간과 수명주기 비용 등을고려한 구조적 단순함을 요한다. 이러한 요구를 충족시키기 위해 극후판이나 TMCP 강과 같은 고성능 강의 사용이 요구된다. TMCP (Thermo-Mechanical Control Proces)법에 의해 제조되는 TMCP 강은 탄소당량이 적고, 조직이 미세하며, 강도 및 인성이 좋다. 최근에는 인장강도 60MPa급의 고강도 TMCP 강인 SM570-TMC 강이 개발되어 토목구조물에 일부 적용되고 있으며, 점차 그 영역을 확장하려는 추세에 있다. 하지만 이러한 고강도 TMCP 강을 강구조물에 적용하기 위해서는 그 재료적 특성뿐만 아니라 용접 시 발생하는 접합부의 역학적 특징을 명확히 할 필요가 있다. 따라서 본 연구에서는 고온인장실험을 통해서 SM570-TMC 강의 고온시의 기 계적 특성을 조사하였고, 이를 잔류응력 특징을 명확히 하였다.

• Journal of Welding and Joining
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• 제6권1호
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• pp.28-34
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• 1988

The fatigue test was carried out to evaluate the fatigue characteristics of the accelerated cooled (ACC) TMCP steel and its welded joint. From this study, it was confirmed that ACC TMCP steel has higher fatigue strength than conventional steels. After welding, however, the fatigue strength of ACC TMCP steel was deteriorated associated with HAZ softening when weld reinforcement was removed. On the other hand, with weld reinforcement, there is no effect of HAZ softening on the fatigue strength of welded joint because it is strongly dependant on the detail weld geometry i.e., stress concentration factor. Accordingly the fatigue strength of actual welded joint increases with decreasing the stress concentration factor of welded joint, regardless of HAZ softening.

• Journal of Advanced Marine Engineering and Technology
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• 제12권1호
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• pp.47-54
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• 1988

TMCP steel manufactured by controlled rolling followed by accelerated cooling process is known to have extra-ordinary mechanical properties such as tensile strength and toughness. However, there is much uncertainty about the fatigue fracture characteristics of this steel. In this paper, the fatigue fracture behaviour of the TMCP steel in base metal and weldment were inspected through the Dynamic Implant test method. Those results were quantitavely compared with those of the ordinary normalized steel of same strength level. Moreover, the effect of the diffusible hydrogen included in the welded part on the fatigue fracture behaviour were made clear. As the experimental results, the fatigue fracture characteristics of the TMCP steel in case of base metal proved out to be superior to that of the normalized steel. However, the TMCP steel weldment including the diffusible hydrogen appeared to have inferior fatigue characteristics compared with the same conditioned normalized steel weldment.

• 한국화재소방학회논문지
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• 제27권6호
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• pp.21-25
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• 2013

대형화, 초고층 및 고스팬에 부응하기 위한 강재 기술개발의 노력으로 용접성능과 내진성능 그리고 내화성능이 부여된 새로운 강재인 Thermo-mechanical control process (TMCP) 내화강재가 개발되었다. TMCP 내화강재는 기존의 내화강재 생산과정 시 압연과 동시에 정밀한 열처리를 병행함으로 인장력과 용접성을 향상시킬 수 있는 새로운 기술인 TMCP 방법으로 개발되었으며, 화재와 같은 고온에서의 구조적 안전성에 관한 내력평가가 요구되었다. 따라서 본 연구에서는 고온 시 TMCP 내화강재의 내력평가를 목적으로 고온 시 항복강도, 탄성계수를 평가하고 각각에 대한 온도영역별 실험식을 제시하였으며, 이를 일반 내화강재의 고온 특성과 비교, 분석하였다. 또한 각각의 소재로 설정된 H형강 기둥부재를 대상으로 고온 시의 내력을 계산하여 그 안전성을 확인한 결과, TMCP 내화강재의 고온 시 내력특성은 일반강 내화강재의 고온 내력저하 특성보다 열위인 것으로 나타났다.