Review of Reheat Crack in Welded Joint of Low Alloy Heat-Resistant Steels

Chen, Zhongbing; Lv, Yi Shi; Qi, Quan You; Wang, Hai Bo

doi:10.4028/www.scientific.net/kem.730.15

Cited by 3 publications

(2 citation statements)

References 32 publications

(17 reference statements)

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“…RC, also known as stress relief cracking (SRC), is a kind of inter-granular cracking that occurs in the CGHAZ of welded joints during post weld heat treatment (PWHT) or high-temperature service. It is generally considered that the plastic deformation caused by residual stress relaxation exceeds the plastic deformation capacity of GB and eventually leads to inter-granular cracking [9][10][11]. Therefore, improving the hot ductility of CGHAZ, especially the GB plastic bearing capacity, will allow it to resist more deformation during residual stress relaxation and preventing the occurrence of RC.…”

Section: 25cr16wmovnb Steel (Asme Sa213-t23mentioning

confidence: 99%

Influence of boron segregation on the hot ductility of T23 steel CGHAZ

Zhang,

Wang,

2023

Science and Technology of Welding and Joining

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Boron segregates in a non-equilibrium segregation mode at lath, packet, block boundaries as well as prior austenite grain boundaries (PAGBs) in 2.25Cr1.6WVNb steel coarse grain heataffected zone (CGHAZ) during the thermal cycle, and tends to segregate only at PAGBs in the same mode during the high-temperature tensile test. Boron segregation along PAGB increases GB plasticity but not inter-granular strength. This is because the boron segregation at PAGBs occupies the vacancies and other defect positions, which inhibits the nucleation and growth of micro-voids, and reduces plasticity consumption. As a result, the hot ductility of CGHAZ is enhanced.

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Section: 25cr16wmovnb Steel (Asme Sa213-t23mentioning

confidence: 99%

Influence of boron segregation on the hot ductility of T23 steel CGHAZ

Zhang,

Wang,

2023

Science and Technology of Welding and Joining

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“…RC, also known as stress-relief cracking (SRC), occurs in the coarse grain heat-affected zone (CGHAZ) or weld metal (WM) under postweld heat treatment (PWHT) or service at high temperature, with the sensitive temperature range usually being between 500-750°C (932-1382°F) (Refs. [13][14][15][16][17]. The occurrence of SRC usually results in sudden fracture without obvious plastic deformation, which is very dangerous during service.…”

Section: Introductionmentioning

confidence: 99%

Influence of Boron on Stress-Relief Cracking Susceptibility of T23 Steel

ZHENG,

WANG

2024

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The effect of boron on stress-relief cracking (SRC) sensitivity in the coarse grain heat-affected zone (CGHAZ) of ASME SA213-T23 was studied by thermo-mechanical simulation. Then, the fracture mode, microstructure, carbide evolution, and boron segregation were observed by an optical microscope, a scanning electron microscope, a transmission electron microscope, and an electron probe microanalyzer. Finally, the mechanism of increasing boron content to improve SRC resistance was described. The results showed that when the boron content is lower than 0.0038 wt.-%, T23 steel is sensitive to SRC at 550–750°C (1022–1382°F), and the sensitive temperature range narrows as the boron content increases. When the boron content increases to 0.010 wt.-%, SRC can be eliminated. Moreover, boron addition did not improve grain boundary (GB) strength nor did it fundamentally change the fracture mode at high temperatures, but it significantly improved intergranular ductility. This is because the boron segregation at the GB inhibits the precipitation of M23C6 carbides, which reduces the void nucleation and alloy element depletion near the GB, thus significantly improving intergranular plasticity. The improvement of intergranular plasticity gives the grain sufficient time to deform and greatly improves the overall plasticity of the CGHAZ. As a result, the SRC resistance of the welded joint is significantly improved because the stress can be released through enough plastic deformation during postweld heat treatment or service.

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Investigation of stress relief crack susceptibility of CrMoV steels coarse grain HAZ via simulation of uniaxial stress conditions during PWHT

Czeskleba,

Nietzke,

Rhode

et al. 2023

Weld World

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Creep-resistant steels such as the 13CrMoV9-10, used in the construction of thick-walled pressure vessels, are most commonly submerged arc welded (SAW). These steels can develop stress relief cracks (SRC) if the mandatory post weld heat treatment (PWHT) is performed improperly. Current PWHT parameters, such as heating rate and holding time at a specific holding temperature, are based on both empirical experience and conventional free shrinking welding experiments to characterize the SRC-susceptibility of the weld. These cannot adequately depict the higher residual stresses caused by the structurally induced stiffness of the surrounding construction.This study discusses the development of a repeatable, precise, and time-efficient methodology to study the effects of different stress levels and heating rates on the SRC susceptibility of the coarse grain heat-affected zone (CGHAZ). For that purpose, samples were thermically treated to simulate a coarse grain heat-affected zone (CGHAZ) and subsequently exposed to representative levels of stress during the heating phase of a PWHT. The recorded stress and heating rate–dependent strains were mathematically analyzed via curve tracing/calculus to identify interdependent effects. This procedure facilitates the measurement of material characteristics such as carbide growth on grain boundaries at the µm-scale via an integrated value over the entire sample volume. The first and second derivatives show a slight, precipitate-dependent, increase in hardness of the sample, depending on the heating rate and applied stress. This new methodology generates an improved assessment of the SRC susceptibility of SAW microstructures of creep-resistant CrMoV steels.

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Review of Reheat Crack in Welded Joint of Low Alloy Heat-Resistant Steels

Cited by 3 publications

References 32 publications

Influence of boron segregation on the hot ductility of T23 steel CGHAZ

Influence of boron segregation on the hot ductility of T23 steel CGHAZ

Influence of Boron on Stress-Relief Cracking Susceptibility of T23 Steel

Investigation of stress relief crack susceptibility of CrMoV steels coarse grain HAZ via simulation of uniaxial stress conditions during PWHT

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