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<p>This study investigates the failure behavior and underlying mechanism of GH3536 Ni-based superalloy multi-ply bellows. The bellows were manufactured by tungsten inert gas (TIG) welding (Voltage: 12&#xa0;V; Current: 10 A; Ar flow rate: 10 L/min) and tested under simulated service conditions at 1000&#xa0;°C. In the failed bellows, only the outermost layer experienced local bulging and rupture along the longitudinal weld seam, while the inner layers remained intact. Morphological observations and spectroscopic analyses identified the failure mode as ductile tearing, resulting from the coupling of high-temperature creep and oxidation. The fundamental driving force for the failure was the immense internal steam pressure (≈&#xa0;480&#xa0;MPa) generated by the vaporization of residual water, which was entrapped between the outermost two plies during the hydraulic forming process. Quantitative analysis confirmed this. The internal critical pressure corresponding to the strength limit of the GH3536 alloy at 1000&#xa0;°C was 11.9&#xa0;MPa. The actual steam pressure was sufficient to subject the outermost ply to a hoop stress exceeding this limit. This provided a sustained stress source for creep and oxidation damage. The coarse columnar grain structure of the weld zone (average grain width: 26&#xa0;μm; average grain length: 132&#xa0;μm), along with its preferential oxidation in the high-pressure, high-temperature steam environment, served as the weak path for damage accumulation and crack propagation.</p>

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Study on the Mechanism of Selective Outer-Ply Cracking in GH3536 Multi-ply Bellows

  • 期刊论文

  • 发表日期：

    2025年11月18日

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  • Quanhou Zhang,
  • Caixu Wang,
  • Linhong Song,
  • Honghui Sun

摘要

This study investigates the failure behavior and underlying mechanism of GH3536 Ni-based superalloy multi-ply bellows. The bellows were manufactured by tungsten inert gas (TIG) welding (Voltage: 12 V; Current: 10 A; Ar flow rate: 10 L/min) and tested under simulated service conditions at 1000 °C. In the failed bellows, only the outermost layer experienced local bulging and rupture along the longitudinal weld seam, while the inner layers remained intact. Morphological observations and spectroscopic analyses identified the failure mode as ductile tearing, resulting from the coupling of high-temperature creep and oxidation. The fundamental driving force for the failure was the immense internal steam pressure (≈ 480 MPa) generated by the vaporization of residual water, which was entrapped between the outermost two plies during the hydraulic forming process. Quantitative analysis confirmed this. The internal critical pressure corresponding to the strength limit of the GH3536 alloy at 1000 °C was 11.9 MPa. The actual steam pressure was sufficient to subject the outermost ply to a hoop stress exceeding this limit. This provided a sustained stress source for creep and oxidation damage. The coarse columnar grain structure of the weld zone (average grain width: 26 μm; average grain length: 132 μm), along with its preferential oxidation in the high-pressure, high-temperature steam environment, served as the weak path for damage accumulation and crack propagation.