Papers by Author: Ching Yuan Huang

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Authors: T.C. Chen, Wen Hao Chien, Yuan Tsung Wang, Ching Yuan Huang, Hung Wei Yen, Hsin Chih Lin
Abstract: The demand for new materials that provide excellent structural performance while reducing weight and being cost-effectively manufactured is increasing. For applications with high strength requirements, ultra-high strength steels (UHSS) have been widely used. However, with such a high strength level, UHSS are very sensitive to the hydrogen that could be ease by the tempering process. In this research, the correlation of hydrogen and tempering process on commercial UHSS 15B30 has been studied. Results show that the tensile strength (TS) of as-quenched 15B30 is about 1900MPa. After tempering treatment of the quenched 15B30, the TS decreases from 1600MPa to 1200MPa with tempering temperature increased from 200°C to 400°C. The 15B30 specimens, being subjected to hydrogen charge, exhibit the dramatic reduction of mechanical strengths.
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Authors: Chieh Yu, Ta Chien Cheng, Ren Kae Shiue, Tze Ching Yang, Ching Yuan Huang
Abstract: The purpose of this investigation is focused on the direct quench and temper mechanisms of the high strength offshore steel. Microstructural analyses of martensite and retained austenite in the direct quenched steel, simulations of martensitic transformation temperatures, Ms/Mf, and morphologies of bainite and ferrite have been evaluated in the experiment. Additionally, carbide formation after temped at various temperatures and microhardness depth profiles after heat treating are also included in the study. The direct quenched steel is primarily comprised of martensite, bainite and a few retained austenite with Vickers microhardness above 300. Tempered martensite, iron carbide and bainite are widely observed from all tempered specimens.
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Authors: Ta Hung Tseng, Chieh Yu, Ren Kae Shiue, Tze Ching Yang, Ching Yuan Huang
Abstract: Microstructures, Vickers depth profiles and low-temperature toughness of the tempered direct water quenched steels have been evaluated in the experiment. Martensite dominates the direct quenched specimen, and it is brittle at low-temperature toughness test. The toughness of direct quenched steel is improved when it is tempered at 500 °C for 1800 s. However, increasing the tempering temperature from 500 °C to 660 °C has little effect on low-temperature toughness of the steel. The application of offshore steel must avoid bainite formation. Tempering treatment is very effective to improve low-temperature toughness of the martensite dominated structure.
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Authors: Tze Ching Yang, Ching Yuan Huang, Ta Chien Cheng, Chieh Yu, Ren Kae Shiue
Abstract: The purpose of this investigation is focused on two high strength low alloy steels for offshore application. TTT, CCT curves, Vickers depth profiles and microstructures of direct water quenched steels are evaluated in the experiment. Microhardness of the direct quenched surface is as high as 400 Hv, and the central region hardness of water quenched specimen is above 250 Hv. Martensite dominates the microstructure of quenched surface. In contrast, the mixture of martensite, bainite and ferrite is widely observed from the center of quenched specimen.
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