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Author: search.filters.author.Wiman, PanyaSubject: search.filters.subject.Brouwer diagram

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    Microstructure and high-temperature oxidation behaviour of AISI 304L stainless steel welds produced by gas tungsten arc welding using the Ar–N2–H2shielding gas
    (2025-01-01)
    Chueaprakha, Sompong
    ;
    Thublaor, Thammaporn
    ;
    Siripongsakul, Thamrongsin
    ;
    Wiman, Panya
    ;
    Chandra-Ambhorn, Walairat
    In the present work, we added 1.5 and 5% v/v hydrogen gas to an Ar–7% N<inf>2</inf> shielding gas for the gas tungsten arc welding of AISI 304L stainless steel to investigate its effect on the weld microstructure and oxidation rate. By using Ar–7% N<inf>2</inf> as a shielding gas, the weld metal contained 2.1% of delta ferrite in an austenite matrix. The addition of 1.5 and 5% hydrogen gas in the shielding gas provided the welds with a higher ratio of delta ferrite to austenite matrix, ranging from 3.8 to 6.9%, thus helping reduce the risk of hot cracks. The weld metals were further subjected to an oxidation test in synthetic air at 700°C, and the parabolic oxidation kinetics were observed. The parabolic rate constant of the weld metal produced using the Ar–7% N<inf>2</inf> shielding gas was 5.44 × 10<sup>–13</sup> g<sup>2</sup> cm<sup>–4</sup> s<sup>–1</sup>. When 1.5 and 5% hydrogen gas was added to the Ar–7% N<inf>2</inf> shielding gas, the rate constants were reduced to 64% and 24% of that of the weld produced using only Ar–7% N<inf>2</inf> shielding gas, indicating the promising role of the presence of hydrogen in the Ar–7% N<inf>2</inf> shielding gas on improving the weld metal oxidation resistance for high temperature services.
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    Corrosion behaviour of AISI 430 stainless steel in O2-40%H2O at 800 °C
    (2022-07-15)
    Wiman, Panya
    ;
    Thublaor, Thammaporn
    ;
    Rojhirunsakool, Tanaporn
    ;
    Bidabadi, Mohammad Hassan Shirani
    ;
    Yang, Zhi Gang
    Less mass gain and poorer scale adhesion assessed by the tensile test of the AISI 430 stainless steel exposed to O<inf>2</inf>-40%H<inf>2</inf>O at 800 °C were observed in comparison with the exposure to O<inf>2</inf>. The reduced mass gain was partly due to Cr-species volatilisation while the worse scale adhesion related to pores formed at scale/steel interface. The Brouwer diagrams were proposed to help discuss the water vapour effect on altering defect concentrations that could affect the oxidation rate and scale adhesion of the studied steel.