Microstructural evolution and stress relaxation cracking mechanism for Super304H austenitic stainless steel weld metal

Xiao, Xiaopeng; Li, Dianzhong; Li, Yiyi; Lu, Shanping

doi:10.1016/j.jmst.2021.06.010

Cited by 13 publications

(7 citation statements)

References 26 publications

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“…Pommier found that microcavity nucleation occurs in areas of high residual stresses due to the presence of intergranular M 23 C 6 carbides [18]. The appearance of carbides results in a discontinuous stress distribution at the intergranular carbide-matrix interface [21]. Hence, micro-cracks initiate at this weakest interface under tensile stress.…”

Section: Testing a Fractured Valvementioning

confidence: 99%

“…Hence, micro-cracks initiate at this weakest interface under tensile stress. Some authors [21] state that the presence of intergranular particles can induce intergranular strengthening and weakening of the boundary zones. This results in a difference in strength between GBs and grain interiors.…”

Section: Testing a Fractured Valvementioning

confidence: 99%

“…However, carbide precipitations can also influence this mechanism. Under long-term ageing conditions, intergranular M 23 C 6 carbides formed in Super304H steels were found to be more prone to fracture than intergranular nitrocarbides Nb(C,N) [21].…”

Section: Introductionmentioning

confidence: 96%

“…Formation of (Nb, Ti)C carbides should reduce the amount of carbon that causes the formation of M 23 C 6 and therefore the tendency for DCC [20]. However, on the other hand, there is a body of evidence that the presence of intergranular precipitates promotes the strengthening of the grain interior, which also translates into a weakening of the GBs [21]. It was found in [22] that the presence of precipitates at the GBs forming a carbon content of 0.024 wt% reduced the sensitivity to DDC compared to an alloy with an ultra-low carbon content.…”

Section: Introductionmentioning

confidence: 99%

“…Another type of cracking is called reheat cracking (RC) or stress relief/relaxation cracking (SRC), which is an intergranular failure caused by the relaxation of residual macro stresses at high temperatures [18,21]. The main mechanical condition for the appearance of RC has been found to be the presence of tensile residual stresses in the material prior to exposure to high temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Metallographic Evaluation of Increased Susceptibility to Intermediate Embrittlement of Engine Valve Forgings Made of NCF 3015 High Nickel and Chromium Steel

Lachowicz,

Zwierzchowski,

Hawryluk

et al. 2023

Materials

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This paper focused on determining the increased tendency of cracking after the die forging process of high nickel and chromium steel. The increase in carbon content in austenitic nickel–chromium steel promoted the tendency of valve forgings to forging intergranular crack on the valve head. Attention was paid to issues related to the chemical composition of the material to be considered when hot forming nickel–chromium steel components. Optical and scanning electron microscopies were used to examine the microstructure and fracture features of the samples removed from a fractured valve head. The embrittlement was due to microcavity formation at grain boundaries. Creep theory at grain boundaries was used to explain crack formation. The tensile behavior was interpreted from the evolution of the microstructure during deformation and referred to intermediate brittleness to explain the effect of carbon. It was found that the increased carbon content of the nickel–chromium steel and the strong undercooling observed at the edges of the valve head are factors that promote a reduction in grain boundary cohesion and enhance intermediate temperature embrittlement. Finally, it was found that the formation of a heterogeneous structure manifested by the presence of grain boundary M23C6-type carbides in the austenitic matrix was most likely related to the occurring brittleness.

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Section: Testing a Fractured Valvementioning

confidence: 99%

Section: Testing a Fractured Valvementioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Metallographic Evaluation of Increased Susceptibility to Intermediate Embrittlement of Engine Valve Forgings Made of NCF 3015 High Nickel and Chromium Steel

Lachowicz,

Zwierzchowski,

Hawryluk

et al. 2023

Materials

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Effect of Welding Microstructure on Stress Relaxation Cracking Studied by Controlled Residual Stress Generation in a 316L(N) Austenitic Stainless Steel

Py-Renaudie,

Goncalves,

Pascal

et al. 2023

Metall Mater Trans A

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The influence of heterogeneous welding microstructure on the stress relaxation cracking (SRC) in the SRC-resistant 316L(N) steel was investigated. To trigger SRC, pre-straining by compression was applied after the welding and before subsequent stress relaxation by heat treatment. To this end, compact tension (CT) type specimens were extracted from thick plates welded on both sides. The notch was aligned with the welding centreline and notch root across the thickness, thereby crossing the heterogeneous microstructure. Residual stresses and strain fields induced by welding and precompression were estimated by 3D finite element simulations and values of the same order of magnitude were obtained for all regions of the weld. After thermal heat treatment at 575 °C for 580 and 1470 h of the welded and further pre-strained CT samples, intergranular cavities and cracks similar to those found after the creep were observed. Cavities appeared exclusively on intergranular carbides and associated intermetallic precipitates. In the fusion zone (FZ), cavities preferentially nucleated on phases issued from the decomposition of the vermicular ferrite formed during welding. The highest number of cracks was systematically found in the coarse grain heat affected zone (CGHAZ) of the weld. An increase in both pre-compression load and relaxation time led to an increase in damage after the heat treatment.

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Diphylleia Grayi-Inspired Intelligent Temperature-Responsive Transparent Nanofiber Membranes

Zhao,

Liu,

Lin

et al. 2024

Nano-Micro Lett.

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Nanofiber membranes (NFMs) have become attractive candidates for next-generation flexible transparent materials due to their exceptional flexibility and breathability. However, improving the transmittance of NFMs is a great challenge due to the enormous reflection and incredibly poor transmission generated by the nanofiber-air interface. In this research, we report a general strategy for the preparation of flexible temperature-responsive transparent (TRT) membranes, which achieves a rapid transformation of NFMs from opaque to highly transparent under a narrow temperature window. In this process, the phase change material eicosane is coated on the surface of the polyurethane nanofibers by electrospray technology. When the temperature rises to 37 °C, eicosane rapidly completes the phase transition and establishes the light transmission path between the nanofibers, preventing light loss from reflection at the nanofiber-air interface. The resulting TRT membrane exhibits high transmittance (> 90%), and fast response (5 s). This study achieves the first TRT transition of NFMs, offering a general strategy for building highly transparent nanofiber materials, shaping the future of next-generation intelligent temperature monitoring, anti-counterfeiting measures, and other high-performance devices.

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Microstructural evolution and stress relaxation cracking mechanism for Super304H austenitic stainless steel weld metal

Cited by 13 publications

References 26 publications

Metallographic Evaluation of Increased Susceptibility to Intermediate Embrittlement of Engine Valve Forgings Made of NCF 3015 High Nickel and Chromium Steel

Metallographic Evaluation of Increased Susceptibility to Intermediate Embrittlement of Engine Valve Forgings Made of NCF 3015 High Nickel and Chromium Steel

Effect of Welding Microstructure on Stress Relaxation Cracking Studied by Controlled Residual Stress Generation in a 316L(N) Austenitic Stainless Steel

Diphylleia Grayi-Inspired Intelligent Temperature-Responsive Transparent Nanofiber Membranes

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