Development of Technological Recommendations for Improving the Quality of Welded Joints of Pipeline System Elements Made of Stainless Alloys for Aviation Purposes

2021 ◽  
pp. 41-53
Author(s):  
A.S. Kravchenko ◽  
P.V. Bakhmatov
Keyword(s):  
Stainless Steel ◽  
Welded Joints ◽  
Arc Welding ◽  
Welding Parameters ◽  
Pipeline System ◽  
Welding Equipment ◽  
Pipeline Systems ◽  
Single Production ◽  
Thin Walled

There is a substantial body of literature on improving the quality of welded joints of stainless steels. However, as practice shows, in a single production facility the level of defects can be quite high, which can be explained by the specifics and features of this production. Currently, there is insufficient information about the optimal modes of argon arc welding of thin-walled stainless steel pipe systems. The welding modes given in the current regulatory documentation are not always relevant and optimal for modern welding equipment. In addition, there is no model to predict the change in the mechanical properties of the weld depending on the welding parameters. This leads to the need to carry out a series of laborious experiments for each new alloy or piece of welding equipment in order to build diagrams that allow you to determine the range of parameters for obtaining the best quality welded joints. This study examines the influence of argon arc welding on the structure and properties of welded joints of thin-walled stainless steel elements of pipeline systems. A linear regression model is obtained that reflects the dependence of the tensile strength of the welded joints on the argon arc welding mode. Technological recommendations for manufacturing welded elements for stainless steel pipeline systems for aviation purposes are developed.

scholarly journals Contributions Regarding the Use of Mechanical Vibrations in Order to Improve the Properties of Steels and Welded Joints Used in Metal Constructions

2020 ◽  
Vol 21 (2) ◽  
pp. 67-71
Author(s):  
Gheorghe Novac ◽  
Bogdan Novac
Keyword(s):  
Welded Joints ◽  
Arc Welding ◽  
Significant Contribution ◽  
Welding Process ◽  
Internal Stresses ◽  
Welding Equipment ◽  
Welding Technology ◽  
Submerged Arc ◽  
Very High

The paper presents aspects regarding the influence of vibrations on the mechanical properties of welded joints, made with basic materials of Spanish and Romanian origin. In this research is presented the practical way to make the necessary assemblies for the proposed tests. The tests show that vibrations have a significant contribution to the quality of welded joints. This is explained by the appearance of several crystallization centres which makes the structure finer. By using vibrations, the atoms are rearranged in the structure, ensuring a proper de-tensioning. The stresses induced in welded metals are significantly reduced by the use of vibration during welding process. The addition materials have a significant contribution to the emergence of stresses in welded joints as well. These stresses can contribute to the appearance of microstructural constituents with significant hardness. The welding equipment and technologies used also have a significant contribution to the emergence of the remaining stresses. For example, the submerged arc welding technology (SAF) can introduce very high internal stresses. By using vibrations during the welding process, it is achieved a fine structure and a significant reduction of remaining stresses in the welded joints.

scholarly journals Influence of welding method on microstructural creation of welded joints  

2011 ◽  
Vol 57 (Special Issue) ◽  
pp. S50-S56 ◽  
Author(s):  
P. Čičo ◽  
D. Kalincová ◽  
M. Kotus
Keyword(s):  
Welded Joints ◽  
Arc Welding ◽  
Welded Joint ◽  
Gas Metal Arc Welding ◽  
Structural Phase ◽  
Welding Parameters ◽  
Welding Method ◽  
Welding Technology ◽  
Metal Arc Welding

This paper is focused on the analysis of the welding technology influence on the microstructure production and quality of the welded joint. Steel of class STN 41 1375 was selected for the experiment, the samples were welded by arc welding including two methods: a manual one by coated electrode and gas metal arc welding method. Macro and microstructural analyses of the experimental welded joints confirmed that the welding parameters affected the welded joint structure in terms of the grain size and character of the structural phase.

Influence of welding parameters on pit initiation and pit growth in welded joints of X5CrNi18-10 stainless steel

2018 ◽  
Vol 63 (1) ◽  
pp. 167-179 ◽  
Author(s):  
Bore V. Jegdić ◽  
Biljana M. Bobić ◽  
Bojana M. Radojković ◽  
Behar Alić
Keyword(s):  
Stainless Steel ◽  
Welded Joints ◽  
Welding Parameters ◽  
Pit Initiation

Using of Welding Virtual Numerical Simulation as the Technical Support for Industry

2016 ◽  
Vol 1138 ◽  
pp. 49-55
Author(s):  
Marek Slováček ◽  
Josef Tejc ◽  
Mojmír Vaněk
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Welded Joints ◽  
Welding Process ◽  
Austenitic Steels ◽  
Welding Parameters ◽  
Efficient Production ◽  
Weld Joints ◽  
Mechanical Properties Prediction

Welding as a modern, highly efficient production technology found its position in almost all industries. At the same time the demands on the quality of the welded joints have been constantly growing in all production areas. Great demand on the quality of the welded joints consequently causes more experimental or prototype – so called – validation joints that take place before the welding of final construction. These experiments, prototypes aim at – for instance – defining the appropriate welding technology, material, pre-heating, welding parameters, clamping condition and optimizing the welding process. Naturally, these experiments and prototypes make production more expensive. Numerical simulations of welding – in the area of production preparation as well as of production proper – have been frequently used recently. Numerical simulations supported by experimental measurements can simulate the actual welding process very close to reality. The new material models for hardness and mechanical properties prediction based on numerical simulation solution will be introduced.The paper covers some typical welding cases from energy industrial sector. The homogenous and heterogeneous weld joints from modern energy Cr-Mo-Ni-V steels (including modern austenitic steels) were done as prototype welding. The numerical simulation of these weld joints including post weld heat treatment process were done and welding technologies were optimised based on the numerical simulation results. The calculated hardness was compared with real measurements. During project the complete material properties which are needed for numerical simulation were measured. Simplify numerical lifetime prediction of weld joints including results from numerical welding analyse (as residual stresses and plastic deformation) were done.

Welding and Fabrication of Stainless Steel Equipment for 500MWe Prototype Fast Breeder Reactor

2013 ◽  
Vol 794 ◽  
pp. 305-315
Author(s):  
Prabhat Kumar
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Arc Welding ◽  
Welding Distortion ◽  
Fast Breeder Reactor ◽  
Mandatory Requirement ◽  
Main Vessel ◽  
Grid Plate ◽  
Thin Walled ◽  
Inner Vessel

Austenitic stainless steel is the major structural material for the primary and secondary sodium systems (except for the steam generators) for the currently operating and planned fast reactors all over the world. The boundaries of sodium systems of Prototype Fast Breeder Reactor (PFBR) is designed so as to have an extremely low probability of leakage, rapidly propagating failure and gross rupture under the static & dynamic loads expected during various operating conditions.The degradation of material properties (e.g. effect of sodium, temperature and irradiation), transients, residual stresses, flaw size etc. are the important considerations, which shall be taken into account. The principal material of construction for PFBR is austenitic stainless steel of grade 316LN/304LN. The scope of welding and fabrication of PFBR components is too large due to versatile types of systems with varieties of components with complex constructional features. High operating temperature of various systems causing high stresses are to be minimized by designing thin walled structure. Most of the Nuclear Steam Supply System (NSSS) components are thin walled and require manufacturing in separate nuclear clean hall conditions to assure the quality.The welding with stringent tolerances along with high distortion in stainless steels due to high thermal expansion and low thermal conductivity makes the fabrication extremely challenging.The welding standards and acceptance criteria of PFBR equipment is stringent compared to other industrial specification. Manufacture of over dimensional components (diameter greater than 12m and thickness upto 40mm) such as MainVessel, Safety Vessel, Inner Vessel involves die pressing of large size dished end & conical petals. The solution annealing of cold worked petals is a mandatory requirement if strain exceeds 10%. Innovative welding techniques and many trials were conducted on mock up for establishing the process parameters. The forming techniques, bending methods and welding procedures were qualified with stringent non-destructive and destructive examinations and testing before taking up the actual job. Thermal Baffle has two large concentric cylindrical shells, inner and outer shells of about 12.4m diameter and fabrication is a challenging task. PFBR also involves dissimilar joint welding between carbon steel (A48P2) and austenitic stainless steel (316LN) at integration location of roof slab & main vessel. This welding is carried out by combination of Gas Tungsten Arc Welding (GTAW) & Shielded Metal Arc Welding (SMAW) processes using ER 309L & E 309-16 welding consumables with controlled heat input to minimize the dilution of carbon & distortion. The weld between primary pipe & grid plate cannot be accessed for in-service inspection and therefore requires extra-ordinary skilled welders. Space constraints & lack of accessibility makes the welding & inspection challenging. This paper highlights the welding and fabrication aspects of few major, over dimensional and critical equipment of 500MWe Prototype Fast Breeder Reactor. Keywords: Stainless Steel, Main Vessel, Safety Vessel, Inner Vessel, Grid Plate, PFBR, SS welding, distortion.

Effect of friction welding parameters and heat treatment on the quality of welded joints in creep-resisting deformable nickel alloys

2012 ◽  
Vol 26 (9) ◽  
pp. 728-731 ◽  
Author(s):  
V. I. Lukin ◽  
V. G. Koval'chuk ◽  
M. L. Samorukov ◽  
Yu. M. Gridnev ◽  
I. P. Zhegina ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Welded Joints ◽  
Friction Welding ◽  
Nickel Alloys ◽  
Welding Parameters

Springback Analysis of Thin-Walled Stainless Steel Bellow in Hydroforming

2015 ◽  
Vol 1095 ◽  
pp. 855-858 ◽  
Author(s):  
Jing Liu ◽  
Yang Liu ◽  
Lan Yun Li ◽  
Xiao Li ◽  
Shao Fei Yang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Stress Distribution ◽  
Radial Displacement ◽  
Axial Displacement ◽  
Fe Model ◽  
Forming Quality ◽  
Compressive Stresses ◽  
Thin Walled ◽  
Profile Change

Springback has an important influence on the forming quality of thin-walled stainless bellows hydroforming. By developing a FE model, the stress distribution is investigated and springback characteristics of two specification bellows are addressed. The results show that: (1) For tube Φ26×0.5, the maximum circumferential tensile/compressive stresses decrease by 32% and 29.1% after springback, respectively. The maximum longitudinal tensile/compressive stresses decrease by 51.8% and 39.6%, respectively. (2) Three indices are proposed to describe the bellow profile change after springback, namely, radial displacement of crown point; axial displacement of inner point; maximum convolution width. (3) For tube Φ26×0.1, after springback, the inward shrinkage of crown point increases by 0.7%, the bellow axial elongation is 0.76mm, the maximum convolution width increases by 30.3%.

scholarly journals Mechanical Behavior of ARC Welding using Different Flux Materials

2019 ◽  
Vol 9 (2) ◽  
pp. 4344-4349
Keyword(s):  
Stainless Steel ◽  
Arc Welding ◽  
Large Scale ◽  
Welding Process ◽  
Hardness Test ◽  
Welding Parameters ◽  
Small Scale ◽  
Work Piece ◽  
Welding Operation ◽  
Small Scale Industries

To perform welding process on the material under varying conditions with different flux materials, different welding parameters and further subjecting the material to various suitable tests such as tensile test, hardness test, optical tests and study the characteristics of the material under testing. The tests conducted on the welded work piece it is proposed the suitable parameters under which welding of greater precision can be performed. it is also analyzed the working conditions under which the selected work piece material of stainless steel grade 304 would deviate from its desired characteristics. From the results of the tests it is able to determine the conditions that would reduce the characteristics of the welded work piece. Thus it can be further used for reference when the welding process is done on the same material of stainless steel of grade 304. The electrodes that were chosen for this project were selected by the criteria of widely used and chief material in the welding of various grades of stainless steel. The composition of the chemicals that constitute the electrodes were tribiologically analyzed and studied. The need for high precision welding in large scale as well as small scale industries is relatively high as the threshold for errors in such areas are greatly undesirable. The results of this study would greatly contribute to the reduction of errors and defects in the welding operation.

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