Analytical Evaluation of Strengthening, Local Internal Stresses and Microderformations in Welded Joint Metal during Wet Underwater Welding

2021 ◽  
Vol 410 ◽  
pp. 342-347
Author(s):  
Sergey Yu. Maksimov ◽  
Olena M. Berdnikova ◽  
Olena A. Prilipko
Keyword(s):  
Electromagnetic Field ◽  
Dislocation Density ◽  
Crack Resistance ◽  
Welded Joints ◽  
Lower Bainite ◽  
External Electromagnetic Field ◽  
Internal Stresses ◽  
Underwater Welding ◽  
Upper Bainite ◽  
Local Internal Stresses

Analysis of structural factor influence on local internal stresses and zones of deformation localization in upper and lower bainite structures in welded joints of low-alloy steel at wet underwater welding was performed. It is established that when welding joints under the water and applying an external electromagnetic field in the metal of the heat-affected zone (HAZ), a finer-grained substructure is formed with a general decrease in the dislocations density and with their uniform distribution. Estimates of the local internal stresses level considering the dislocation density distribution in the structural zones of their localization show that their maximum level is formed in the metal of the HAZ overheating region at welding without the external electromagnetic field along the upper bainite laths boundaries. The upper bainite structure is characterized by forming localized deformation zones, where the most significant dislocation density gradients are observed. This can lower the crack resistance of welded joints. Low values of local internal stresses are characteristic of welded joints obtained in the modes applying an external electromagnetic field. This is facilitated by the overall decrease in the dislocation density and their uniform distribution in the lower bainite structural components, which provides high crack resistance of welded joints.

scholarly journals Microstructure and dislocation hardening mechanism of VT8 alloy

2021 ◽  
Vol 99 (3) ◽  
pp. 22-31
Author(s):  
Z.A. Duriagina ◽  
◽  
I.A. Lemishka ◽  
O.S. Filimonov ◽  
A.M. Trostianchyn ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Titanium Alloy ◽  
Dislocation Density ◽  
Internal Stresses ◽  
Structural Components ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Local Internal Stresses ◽  
Scalar Dislocation Density

Specimens of titanium alloy VT8, which is used for the manufacture of gas turbine engine elements, were investigated in the initial state and after fracture toughness testing by methods of transmission electron microscopy and diffraction analysis. The features of the microstructure, structure morphology, the nature of phase distribution and structural components were established. Defects in the crystal structure, the formations of dislocation inhomogeneities and local concentrators of internal stresses were identified using JEM-200CX transmission electron microscope. The scalar dislocation density is determined by the secant method. The study of VT8 titanium alloy samples before and after destruction, which is used for the manufacture of GTE elements, using the methods of transmission electron microscopy and diffraction analysis was made. Microstructural investigations for a detailed analysis of the structure features, morphology and phase formations distribution, as well as their components establishment, the nature of crystal lattice defects, the formation of dislocation inhomogeneities and local concentrators of internal stresses were performed on a JEM-200CX transmission electron microscope. The scalar dislocation density was measured by the secant method. It is shown that the studied samples of VT8 titanium alloy are characterized by a two-phase (α + β) microstructure in the form of large -phase plates, 0.15 ... 0.76 μm in size, interspersed with an insignificant amount of thin-plate β-phase, with a size of 0.04 ... 0.21 μm. Based on scalar dislocation densities, the level of local internal stresses in the places of dislocation accumulations, which are sources of crack formation, was analytically estimated. Dispersed particles of secondary phases characterized by different sizes and different structure morphologies were identified. The calculated dislocation densities and an estimate of the average distance over which they move in the process of deformation are used as the basis for creating a statistical map of localized deformation level indicators in the alloy structural components and on the fracture surface. It is shown that as a result of fracture after testing for low-cycle fatigue, the dislocation density increases, the level of local internal stresses increases, and the formation of a cellular structure in the α- and β-phases and deformation grain-boundary defects occurs. Keywords: VT8 alloy, dislocation structure, microstructure, transmission electron microscopy, local internal stresses.

TREATMENT OF WELDED JOINTS BY A PULSE ELECTROMAGNETIC FIELD WITH SMALL SKIN-EFFECT

2018 ◽  
Vol 2018 (50) ◽  
pp. 106-114
Author(s):  
Yu. Vasetskiy ◽  
◽  
I. Kondratenko ◽  
I. Mazurenko ◽  
М. Pashchyn ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Welded Joints ◽  
Skin Effect ◽  
Pulse Electromagnetic Field

Recovery in 15%Cr Ferritic Stainless Steel after Large Strain Deformation

2007 ◽  
Vol 558-559 ◽  
pp. 119-124
Author(s):  
Andrey Belyakov ◽  
Kaneaki Tsuzaki ◽  
Yoshisato Kimura ◽  
Yoshinao Mishima
Keyword(s):  
Stainless Steel ◽  
Low Temperature ◽  
Dislocation Density ◽  
Ambient Temperature ◽  
Ferritic Stainless Steel ◽  
Vickers Hardness ◽  
Subgrain Size ◽  
Large Strain ◽  
Internal Stresses ◽  
Cumulative Strain

15%Cr ferritic stainless steel was machined in rectangular samples and then processed by multiple forging to a total cumulative strain of 7.2 at an ambient temperature. The large strain deformation resulted in almost equiaxed submicrocrystalline structure with a mean grain/subgrain size of 230 nm and about 2.2×1014 m-2 dislocation density in grain/subgrain interiors. The annealing at a relatively low temperature of 500oC did not lead to any discontinuous recrystallizations. The grain/subgrain size and the interior dislocation density slightly changed to 240 nm and 2.1×1014 m-2, respectively, after annealing for 30 min, while the Vickers hardness decreased from 3140 MPa in the as-processed state to 2900 MPa. This annealing softening was attributed to remarkable release (by 50%) of internal stresses, which are associated with a non-equilibrium character of strain-induced grain/subgrain boundaries.

scholarly journals PSEUDOCLASSICAL MODEL OF SPINNING PARTICLE WITH ANOMALOUS MAGNETIC MOMENTUM

1993 ◽  
Vol 08 (05) ◽  
pp. 463-468 ◽  
Author(s):  
D.M. GITMAN ◽  
A.V. SAA
Keyword(s):  
Electromagnetic Field ◽  
External Electromagnetic Field ◽  
Invariant Form ◽  
Pauli Equation ◽  
Spinning Particle ◽  
Dirac Quantization

A generalization of the pseudoclassical action of a spinning particle in the presence of an anomalous magnetic momentum is given. The action is written in reparametrization and supergauge invariant form. The Dirac quantization, based on the Hamiltonian analyzes of the model, leads to the Dirac-Pauli equation for a particle with an anomalous magnetic momentum in an external electromagnetic field. Due to the structure of first class constraints in that case, the Dirac quantization demands for consistency to take into account an operator’s ordering problem.

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