Numerical Investigation of Strength Mismatch Effect on Ductile Crack Growth Resistance in Welding Pipe

Su, Lin; Xu, Jie; Song, Wenping; Chu, Lingyu; Gao, Hanlin; Li, Pengpeng; Berto, Filippo

doi:10.3390/app10041374

Cited by 4 publications

(4 citation statements)

References 35 publications

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“…Sample 1.6511Si2V has the highest volume fraction of retained austenite among the samples; despite the larger grain size due to the possibility of simultaneous blinding and the TRIP phenomenon resulting from its retained austenite, it was able to absorb great energy before failure. Rare earth elements, besides decreasing the grain size, which leads to increased fracture toughness [45][46][47][48][49][50][51][52], also increase the grain boundary strength [36]. It seems that there is an increase in energy required for the fracture of the 1.6511Si2M sample compared to the standard sample, and the 1.6511Si2 sample has a higher grain boundary volume and higher grain boundary strength compared to other samples.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Effect of Vanadium and Rare Earth on the Structure, Phase Transformation Kinetics and Mechanical Properties of Carbide-Free Bainitic Steel Containing Silicon

et al. 2022

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Carbide-free bainitic (CFB) steels with a matrix of bainitic ferrite and thin layers of retained austenite, to reduce the manufacturing costs, usually do not contain alloying elements. However, a few reports were presented regarding the effect of alloying elements on the properties of these steels. Thus, this study evaluates the effects of vanadium and rare earth (Ce-La) microalloying elements on the structure, phase transformation kinetics, and mechanical properties of carbide-free bainite steel containing silicon fabricated by the casting and austempering procedure. Optical and scanning electron microscopy (OM and SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) were used to study the microstructure and phase structure. The transformation kinetics were examined by a dilatometry test. Hardness, tensile, and impact tests evaluated the mechanical properties. Due to adding alloying elements, the fracture toughness and change in matrix phases relation was studied by the crack tip opening displacement (CTOD) test and SEM fractography. The microstructure of the silicon added sample was completely carbide-free bainite. The test results showed vanadium helped CFB formation, even in continuous cooling. The primary austenite grain (PAG) size grew by vanadium addition. The EBSD phase map illustrates an increment in the percentage of retained austenite by vanadium. In contrast, the addition of 0.03 wt% rare earth reduced the primary austenite grain size and reduced the retained austenite content. The results of the dilatometry test confirmed that vanadium and rare earth addition both reduced the critical cooling rate of the bainite transformation. Vanadium leads to an earlier cessation of bainite transformation, while rare earth elements postpone this transformation. Mechanical tests showed that the tensile strength of carbide-free bainite steels was strongly influenced by the morphology and volume fraction of austenite. Retained austenite, when transformed to martensite during the transformation-induced plasticity (TRIP) phenomenon, leads to increased tensile strength and fracture toughness, or retained austenite with a film-like shape prevents the growth of cracks by blinding the crack tip. The result of the CTOD test exhibited that retained austenite plays the leading role in increasing crack resistance when TRIP occurs.

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Section: Mechanical Propertiesmentioning

confidence: 99%

Effect of Vanadium and Rare Earth on the Structure, Phase Transformation Kinetics and Mechanical Properties of Carbide-Free Bainitic Steel Containing Silicon

et al. 2022

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“…erefore, it is necessary to calculate and predict the crack propagation direction and the strain eld and stress eld at the crack tip. In general, the mechanical property mismatch is de ned by the strength mismatch as the ratio of the yield strength of the weld metal to the base metal [12][13][14]. In most studies, the welded joint is simpli ed as a sandwich structure.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Crack Tip Mechanical Field of Inhomogeneous Materials in Welded Joints by USDFLD Subroutine

Yuan

Hao

et al. 2022

Advances in Materials Science and Engineering

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The unevenly distributed mechanical properties of welded joints are one of the important factors, which affect welded joints’ safety seriously. The user-defined field (USDFLD) subroutine in ABAQUS finite element software can introduce variable-dependent material properties. This method can define inhomogeneous materials whose mechanical parameters depend on spatial coordinates and can be used to characterize the uneven mechanical properties of heat-affected zone and fusion zone. By establishing the static crack finite element model of welded joint with continuous change in yield strength, the sudden change in mechanical field in the numerical simulation process of sandwich structure model is eliminated. Compared with the existing numerical simulation methods of local mechanical heterogeneity of welded joints, this method provides a method to realize the structural integrity evaluation of welded joints.

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“…In general, the mechanical property mismatch is defined by the strength mismatch ratio of the yield strength of the weld metal and base metal. Many efforts were made regarding the effect of strength mismatch on the crack-tip stress and strain field [ 5 ] and corresponding crack driving force [ 6 , 7 ], crack-tip constraint [ 8 , 9 ]. In most of these studies, the default weld metal and base metal have the same hardening properties, i.e., the true stress–strain curves of two metals after yielding are parallel.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mechanical Heterogeneity on Strain and Stress Fields at Crack Tips of SCC in Dissimilar Metal Welded Joints

et al. 2021

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The crack tip strain and stress condition are one of the main factors affecting stress corrosion cracking (SCC) behaviors in the dissimilar metal welded joint of the primary circuit in the pressurized water reactor. The mechanical property mismatch of base metal and weld metal can significantly affect the stress and strain condition around the crack tip. To understand the effect of different weld metals on strain and stress fields at SCC crack tips, the effects of strength mismatch, work hardening mismatch, and their synergy on the strain and stress field of SCC in the bi-material interface, including plastic zone, stress state, and corresponding J-integral, are investigated in small-scale yielding using the finite element method. The results show a significant effect of the strength mismatch and work hardening mismatch on the plastic zone and stress state in the weld metal and a negligible effect in the base metal. J-integral decreases with the single increase in either strength mismatch or work hardening mismatch. Either the increase in strength mismatch or work hardening mismatch will inhibit the other’s effect on the J-integral, and a synthetic mismatch factor can express this synergistic effect.

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Numerical Investigation of Strength Mismatch Effect on Ductile Crack Growth Resistance in Welding Pipe

Cited by 4 publications

References 35 publications

Effect of Vanadium and Rare Earth on the Structure, Phase Transformation Kinetics and Mechanical Properties of Carbide-Free Bainitic Steel Containing Silicon

Effect of Vanadium and Rare Earth on the Structure, Phase Transformation Kinetics and Mechanical Properties of Carbide-Free Bainitic Steel Containing Silicon

Characterization of Crack Tip Mechanical Field of Inhomogeneous Materials in Welded Joints by USDFLD Subroutine

Effect of Mechanical Heterogeneity on Strain and Stress Fields at Crack Tips of SCC in Dissimilar Metal Welded Joints

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