scholarly journals Molding gate optimization for weld line location away from structures loaded area

2021 ◽  
Vol 1925 (1) ◽  
pp. 012056
Author(s):  
E I Kurkin ◽  
O E Lukyanov ◽  
V O Chertykovtseva ◽  
O U Espinosa Barcenas
Keyword(s):  
Weld Line ◽  
Loaded Area

scholarly journals Failure Analysis of Premature Corrosion of HF Seam-Welded Steel Pipe in Central Heating System

2021 ◽  
Author(s):  
Dorota Tyrala ◽  
Bogdan Pawlowski
Keyword(s):  
High Frequency ◽  
Energy Dispersive Spectrometry ◽  
Weld Line ◽  
Welding Process ◽  
Heating System ◽  
Bond Line ◽  
Steel Pipe ◽  
Huge Number ◽  
Welded Steel ◽  
Central Heating

AbstractPremature corrosion in the form of longitudinal cracking in a high-frequency (HF) induction seam-welded steel pipe occurred after just 24 months in service. The failed pipe was investigated to reveal the main cause of its failure, and the results of microstructural examinations (light optical microscopy, scanning electron microscopy with energy-dispersive spectrometry) suggest that the failure resulted from an HF induction welding process defect—a so-called cast weld, that is, a huge number of iron oxides in the weld line caused by insufficient ejection of the molten metal from the bond line.

scholarly journals Static ultrasonic welding of carbon fibre unidirectional thermoplastic materials and the influence of heat generation and heat transfer

2021 ◽  
pp. 002199832097681
Author(s):  
F Köhler ◽  
IF Villegas ◽  
C Dransfeld ◽  
A Herrmann
Keyword(s):  
Cross Sections ◽  
Weld Line ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Thermoplastic Composites ◽  
Squeeze Flow ◽  
Anisotropic Flow ◽  
Lap Shear ◽  
Anisotropic Thermal Conductivity ◽  
Edge Defects

Ultrasonic welding is a promising technology to join fibre-reinforced thermoplastic composites. While current studies are mostly limited to fabric materials the applicability to unidirectional materials, as found in aerospace structures, would offer opportunities for joining primary aircraft structures. However, due to the highly anisotropic flow of a molten unidirectional ply undesired squeeze flow phenomena can occur at the edges of the weld overlap. This paper investigates how the fibre orientation in the plies adjacent to the weld line influences the welding process and the appearance of edge defects. Ultrasonic welding experiments with different layups and energy director configurations were carried out while monitoring temperatures at different locations inside and outside the weld overlap. The joints were characterized by single lap shear tests, analysis of corresponding fracture surfaces and microscopic cross-sections. Results showed that the anisotropic flow and the anisotropic thermal conductivity of the plies adjacent to the weld line have a distinct effect on the appearance and location of edge defects. By using energy directors that cover only part of the weld overlap area a new approach was developed to mitigate edge defects caused by the highly directional properties of the unidirectional plies.

The extent of relaxation of weld residual stresses on cutting out cross-weld test-pieces

2009 ◽  
Vol 24 (S1) ◽  
pp. S31-S36 ◽  
Author(s):  
J. Altenkirch ◽  
A. Steuwer ◽  
M. J. Peel ◽  
P. J. Withers
Keyword(s):  
Thin Plate ◽  
Mechanical Performance ◽  
Characteristic Length ◽  
Weld Line ◽  
Proper Understanding ◽  
Test Pieces ◽  
Weld Residual Stress ◽  
Cutting Out ◽  
Empirical Curve ◽  
Lateral Width

Weld residual stress (RS) measurements are often undertaken on test-pieces which have been cut out from large components, yet it remains unclear to what extent the RSs in test-pieces are representative of those present in the original component. Similarly weld mechanical performance tests are frequently undertaken on cross-weld test-pieces without a proper understanding of the level or influence of retained RS. We present a systematic study of the relaxation of longitudinal RS in thin-plate butt welds produced using different materials and welding methods (FSW, laser-MIG, and pulsed-MIG). In each case the RSs were measured repeatedly in the same location as the welds were progressively and symmetrically cut down. Although cutting inevitably leads to stress redistribution, significant relaxation of the longitudinal RS was only observed when the weld length or width was reduced to below a certain value. This critical value appears to correlate with the lateral width of the tensile zone local to the weld-line and may be considered to be the characteristic length as defined in St. Venant’s principle. Further, it was found that the level of stress relaxation as a function of weld length for all the welds studied could be collapsed onto a single empirical curve using a simple approach based on the characteristic length scales of the weld. Given the range of materials and welding methods used, this relation appears to be of general use for thin-plate welds although further work is required to test the limits of its applicability.

Effect of Weld Line Formation on Morphology and Mechanical Properties for 3D-MID Technology

2015 ◽  
Vol 659 ◽  
pp. 659-665
Author(s):  
Supakit Chuaping ◽  
Thomas Mann ◽  
Rapeephun Dangtungee ◽  
Suchart Siengchin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Injection Molding ◽  
Filler Content ◽  
Research Work ◽  
Weld Line ◽  
Processing Conditions ◽  
High Reduction ◽  
Flexural Tests

The topic of this research work was to demonstrate the feasibility of a 3D-MID concept using injection molding technique and investigate the effects of two weld line types on the structure and mechanical properties such as tensile, flexural strength and morphology. In order to obtain more understanding of the bonds between polymer and metals, two different polymer bases of polyphthalamide (PPA) with the same type and amount of filler content were produced by injection molding at the different processing conditions. A mold was designed in such a way that weld and meld line can be produced with different angles by changing as insert inside of the mold. The mechanical properties such as stiffness, tensile strength and flexural strength were determined in tensile and flexural tests, respectively. The results showed in line with the expectation of high reduction on mechanical properties in area where weld/meld lines occurred. The result of tensile test was clearly seen that weld and meld line showed a considerable influence on mechanical properties. The reduction in tensile strength was approximately 58% according to weld line types, whereas in flexural strength was approximately 62%. On the other hand, the effect of the injection times and mold temperatures on the tensile strength were marginal.

Conjugated Heat Transfer in Skirt Hot Box in Pressure Vessels

2006 ◽  
Author(s):  
Hossein Shokouhmand ◽  
Manoochehr Bozorgmehrian
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Temperature Gradient ◽  
Thermal Stresses ◽  
Weld Line ◽  
Pressure Vessels ◽  
Conductive Heat ◽  
Air Pocket ◽  
Cyclic Operation ◽  
Conjugated Heat Transfer

Pressure vessels are common equipment in oil, gas and petrochemical industries. In a hot containing fluid vessel, excessive temperature gradient at junction of skirt to head (weld line), can cause unpredicted high thermal stresses; Thereby fracture of the vessel may occur as a result of cyclic operation. Providing a hot box (air pocket) in crotch space is a economical, applicable and easy mounted method in order to reduce the intensity of thermal stresses. Natural convection due to temperature difference between the wall of pocket, will absorb heat near the hot wall (head of the vessel) and release that near the cold wall (skirt of the vessel), then the skirt wall conducts heat to the earth as a fin. This conjugated heat transfer removes the temperature gradient boundary at welded junction. This phenomena will lead the temperature gradient on the weld line from a sudden to smooth behavior, thereby the skirt-head junction, that is a critical region, could be protected from excessive thermal stresses. In this paper the profit of hot box and conjugated heat transfer in cavity has been demonstrated experimentally. As a result it is shown that the conductive heat transfer through the skirt (which acts as a fin) ensures the continuation of natural convection in the box. Also the governing equations has been solved numerically and compared with experimental results.

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