• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.82-88
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• 2000

The effect of the welding for the offshore structure in the TMCP steel on the fatigue crack propagation rate and crack opening-and-closure behavior was examined. The welding anisotropy of the TMCP steel and crack propagation characteristics of the excessive loading were reviewed. (1) It seemed that a heat which was generated by the welding made a compressive residual stress over the base metal, so fatigue crack propagation rate was placed lower than in case of the base metal. (20 In the base metal, an effect of the anisotropy which has an effect of fatigue crack propagation rate of the excessive load and the constant amplitude laos was not found but in the welding material case, fatigue crack propagation rate of the excessive load in the specimen of the width direction was located in the retard side as compared with a specimen rolling direction. (3) A crack opening ratio of the used TMCP stel in this study was not changed after excessive loading but a retard phenomenon of crack propagation was observed. Consequently, it was thought that all of the retard phenomenon of crack propagation did not only a cause of the crack opening-and-closure phenomenon.

• Fire Science and Engineering
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• v.27 no.6
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• pp.21-25
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• 2013

Fire resistance steel, grading 490 MPa, had developed by using Thermo-mechanical control process (TMCP) and it has better performance at welding, seismic resistance than those of the ordinary structural steel, But the fire resistance performance is required to verify against the ordinary fire resistance, FR 490. Therefore this study was done to make database of mechanical properties at high temperature and to evaluate the structural stability at high temperature in terms of materials and structural member such as H-section from that of FR 490. The result of this study was that the structural stability of TMCP was lower than that of ordinary FR 490 at the range up about $700^{\circ}C$.

• Proceedings of the KWS Conference
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• 1994.10a
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• pp.35-37
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• 1994

• Proceedings of the KWS Conference
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• 1993.10a
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• pp.133-136
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• 1993

• Proceedings of the KWS Conference
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• 1993.10a
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• pp.137-140
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• 1993

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.774-779
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• 2016

This study was performed to study the possibility of TMCP's application for side shell plating curved structures through mechanical property testing to understand if the rules and regulations of DNV and the quality standard of IACS after line heating for TMCP steel and normalizing DH32 material steel could be satisfied. Experimental results showed that TMCP's strength was measured to YS = 385 MPa, 18% higher than the required 315 MPa and TS = 525 MPa, complying with the required range of between 440 and 570 MPa. The minus 20 degree impact test for the Charpy V-Notch complied with the required standard and in addition the hardness test satisfied the requirement of 'Hv10 = 130 ~ 320' by reaching an average of T : 216 and L : 275 respectively.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.79-81
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• 2005

Bridges constructed recently are preferred to have long spans and simple structure details considering not only the function as bridge but scenic beauty, maintenance, construction term and life cycle cost, etc. Therefore, they require high performance steels like extra-thick plate steels and TMCP steels. A TMCP steel produced by themo-mechanical control process is now spot lighted due to the weldability for less carbon equivalent. It improved at strength and toughness in microstructure. Recently, the SM570-TMC steel which is a high strength TMCP steel whose tensile strength is 600MPa has been developed and applied to steel structures. But, for the application of this steel to steel structures, it is necessary to elucidate not only the material characteristics but also the mechanical characteristic of welded joints. In this study, the characteristics of residual stresses in welded joints of SM570-TMC steel were studied through the three-dimensional thermal elastic-plastic analyses on the basis of mechanical properties at high temperatures obtained from the elevated temperature tensile test.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.15-21
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• 2014

FCAW(Flux Cored Arc Welding), SAW(Submerged Arc Welding), EGW(Electro Gas Welding), and three-pole SAW are applicable in manufacturing the offshore wind tower. In this paper, mechanical properties of these welded-joints for TMCP steels were evaluated in all above welding processes. The tensile strength of welded-joints for all the welding methods satisfied the standard guideline (KS D 3515). No cracking on weldment was found after the bending test. Changes of weldedments hardness with welding processes were observed. In a weld HAZ (heat-affected zone), a softened HAZ-zone was formed with high heat input welding processes (SAW and EGW). However, the welded-joint fractures were found in the base metal for all cases and small decrease in welded-joint strength was caused by a softened zone. The multi-pole SAW welds exhibited similar mechanical properties comparing to the one with one-pole SAW process.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.276-278
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• 2005

Bridge constructed recently is preferred to have a long span and a simple structure detail considering not only functions as bridge but scenic beauty, maintenance, construction term and life cycle cost, etc. Therefore, it demands a high quality steel like a thick plate steel and a high performance steel. A TMCP steel produced by theme-mechanical control process is now spotlighted due to the weldability for less carbon equivalent. It improved at strength and toughness in microstructure. Resently the SM570-TMC steel, a high strength TMCP steel whose tensile strength is 600MPa, is developed and applied to steel structures. But, for the application of this steel to steel structures, it is necessary to elucidate not only the material characteristics but also the mechanical characteristic of welded joint. In this paper, we investigated the characteristics of residual stresses generated by welding of SM570-TMC steels through an experimental study

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.679-682
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• 2011

The effects of heat input(1.5~3.6kJ/mm) and postweld heat treatment(PWHT, $600^{\circ}C$, 40hr.) on the TMCP HSB600 steel weldments made by GMAW process were investigated. The tensile strength and CVN impact energy of as-welded specimens decreased with increasing heat input. The fine-grained acicular ferrite was mainly formed in the low heat input while polygonal and side plate ferrites were dominated in the high inputs. Meanwhile, tensile strength and hardness of PWHT weldments decreased due to the coarsening of microstructure and reduction of residual stresses.