Microstructural evolution of 9Cr–1Mo deposited metal subjected to weld heating

Wang, Honghong; Zhang, Hanqian; Li, Jin-Fu

doi:10.1016/j.jmatprotec.2008.06.035

Cited by 22 publications

(5 citation statements)

References 8 publications

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“…below A c1 temperature), typically in the range from 720 to 760 • C [3,19]. It is well-known that the "classical" PWHT decreases the hardness of a welded joint and improves its toughness [3,[21][22][23]. However, the remaining problem during creep exposure of these weldments is their premature failure by the "type IV cracking" mode, i.e.…”

Section: Introductionmentioning

confidence: 99%

The influence of PWHT regime on microstructure and creep rupture behaviour of dissimilar T92/TP316H ferritic/austenitic welded joints with Ni-based filler metal

Falat¹,

Výrostková²,

Svoboda³

et al. 2011

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In this paper the dissimilar welded joints between the ferritic (tempered martensitic) steel T92 and the non-stabilised austenitic steel TP316H were investigated in terms of microstructure and creep rupture behaviour characterisation. The welded joints were prepared by the TIG method using the Ni-based filler metal Nirod 600 (Inconel-type). After the welding, the individual weldments were subjected to the two different regimes of post-weld heat treatment (PWHT), either the "classical" PWHT (i.e. subcritical tempering -below Ac1 temperature) or the so-called "full" PWHT including the re-normalisation. The use of "classical" PWHT preserved microstructural gradient in the ferritic steel heat-affected zone (HAZ), which led to a premature creep failure by the "type IV cracking" mode. In contrast, the application of "full" PWHT eliminated the critical HAZ region of T92 steel and changed the creep failure mode to the "interfacial cracking" between the ferritic steel and the Ni-based weld metal. Consequently, this suppression of the "type IV cracking" failure led to a significant creep life increase of the studied ferritic/austenitic welded joints. K e y w o r d s : dissimilar weldment T92/TP316H, post-weld heat treatment (PWHT), microstructure, creep, type IV cracking, interfacial cracking

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Section: Introductionmentioning

confidence: 99%

The influence of PWHT regime on microstructure and creep rupture behaviour of dissimilar T92/TP316H ferritic/austenitic welded joints with Ni-based filler metal

Falat¹,

Výrostková²,

Svoboda³

et al. 2011

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“…The white zone is a direct solidification microstructure in the last weld bead of the weld metal, which is solidified from liquid pool to ambient temperature without undergoing weld heating. It is the zone that plays a vital role in determining the mechanical properties of weld metal [20]. The direct solidification microstructure of weld metal exhibits a columnar dendrite structure and the dendrite grains are straight as shown in Figure 2(b).…”

Section: Resultsmentioning

confidence: 99%

Microstructure, non-metallic inclusions and impact toughness of high-Mn cryogenic steel weld metal

Zhang

Wang

et al. 2022

Science and Technology of Welding and Joining

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Microstructure, inclusions and cryogenic impact toughness of Fe-22.03Mn-0.45C austenitic weld metal were investigated. The results show that microstructure of weld metal consisted of straight columnar dendrites with different orientations. Microsegregation of Mn was observed in the interdendritic regions and Mn depletion thus occurred in the dendrite core, which is suggested to lead to the different morphologies of MnS oxides (Mn-Al-Si-O) depending on their location. MnS patch-type oxides were found at dendrite boundary and MnS shell-type oxides were found at dendrite core. Inclusions as crack sources were distributed in the dimple of cryogenic impact fractography, it was found that MnS patch-type oxides were more ready to act as a crack source and cause the formation of dimples than MnS shell-type oxides.

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“…For weld metals of 9–12% Cr F/M steels, the effect of non-equilibrium solidification and rapid cooling would most likely cause the formation of residual delta-ferrite (δ) [5,6], which was deemed to deteriorate the impact toughness and raise the ductile-to-brittle transition temperature (DBTT) [5,7]. The δ-phase may also transform into a brittle sigma phase on long-term exposure at elevated temperature, which will deteriorate the creep properties [8].…”

Section: Introductionmentioning

confidence: 99%

Formation of delta-ferrite and its effect on impact toughness of GTAW weld metals in a 12 wt-% Cr steel

Tian

Zhang

et al. 2023

Science and Technology of Welding and Joining

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This research focused on the formation of the δ-phase and the corresponding effect on the impact toughness in a GTAW weld metal of a 12%Cr F/M steel. Two kinds of δ-phase were identified: one located at the prior austenitic grain boundaries (PAGBs) (called δ PAGB ) and the other was in the inter-dendritic region (called δ inter ). The δ inter implied that the peritectic transition that occurred at the final stage of solidification in the DSC test, was suppressed in the welding process. A preheating treatment at 95°C decreased optimally the δ-phase fraction and thereby decrease the ductile-brittle transition temperature (DBTT). However, excessive preheating at higher temperatures enhanced the fraction of the δ inter by promoting the micro-segregation and thus increased the DBTT.

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Microstructural evolution of 9Cr–1Mo deposited metal subjected to weld heating

Cited by 22 publications

References 8 publications

The influence of PWHT regime on microstructure and creep rupture behaviour of dissimilar T92/TP316H ferritic/austenitic welded joints with Ni-based filler metal

The influence of PWHT regime on microstructure and creep rupture behaviour of dissimilar T92/TP316H ferritic/austenitic welded joints with Ni-based filler metal

Microstructure, non-metallic inclusions and impact toughness of high-Mn cryogenic steel weld metal

Formation of delta-ferrite and its effect on impact toughness of GTAW weld metals in a 12 wt-% Cr steel

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