scholarly journals Hot cracking tendency of flux-cored arc welding with flux-cored wires of types Ni 6625

Author(s):  
Stefan Burger ◽  
Manuela Zinke ◽  
Sven Jüttner

AbstractDue to their mechanical and corrosive properties, nickel-based alloys are very important in several industrial sectors like power stations, chemical apparatus, and the oil industry. While flux-cored arc welding (FCAW) of carbon steels often uses flux-cored wires (FCW), the use of Ni-based flux-cored wires is industrially less common. The reasons for this include the lower degree of recognition and the higher material costs compared to solid wires. In comparison to solid wires, flux-cored wires have some technological benefits such as the possibility of welding without pulsed arc technology using low-cost standard mixed gases, which has a much lower tendency to weld defects due to high penetration depth. Depending on the slag, the flux-cored wires have a good weldability and excellent mechanical properties. Based on the self-stressed and externally stressed hot crack tests, the basic FCW showed a higher hot cracking susceptibility, contrary to the original assumption. Even if the causes have not yet been finally clarified, a negative influence of the comparatively high sulfur and oxygen contents in the basic FCW is suspected. The weld metal of the solid wires showed the highest hot crack resistance.

2020 ◽  
Vol 65 (2) ◽  
pp. 87-90
Author(s):  
Muralimohan Cheepua ◽  
Jung Parkb ◽  
Hyo Baekc ◽  
Sang Chod

9% Nickel steel has been widely used for storage of liquefied gases, oxygen, and nitrogen in competition with aluminium and austenitic alloys due to its low cost. The development of 9% nickel steel with low ductile-brittle transition temperatures reformed the LNG industry by extensive storage and transportation. In recent years, the demand for 9% nickel steel fuel tanks increasing due to the International Maritime Organization regulations on the reduction of sulphur oxides from 3.5% to 0.5%. Hence, the LNG fuel tanks made with 9% nickel steel became a major part of the international energy industry. However, the weldability, fabrication cost, and productivity of these steels are one of the major concerns for manufacturers. Flux cored arc welding (FCAW) process is the most commonly used joining method for 9% nickel steel with Hastelloy fillers. In FCAW, the loss of deposited metal due to inter pass cleaning by grinding action caused to a reduction in total productivity. Demands for higher production, low cost, better mechanical properties, and reliability are the main driving forces for new developments in this area. To achieve these, the most recently developed "Super-TIG Welding" with C-type filler was successfully applied to improve the 9% Nickel steel weldability, productivity and, mechanical and metallurgical properties of the butt welds. In SuperTIG welding, alloy 625 filler was used, which is cheaper and good weldability over the Hastelloy fillers. The weldability evaluation tests resulted in improved resistance to hot cracking susceptibility using Super-TIG welding. The mechanical properties of the Super-TIG welded joints performed better than the FCAW joints. Most importantly, the productivity of the welding dramatically improved by Super-TIG welding. Super-TIG welding is capable of producing higher feeding rates with clean beads. Therefore, the alloy 625 C-Filler and avoidance of inter pass cleaning in Super-TIG welding resulting in increased productivity. The newly developed Super-TIG welding achieved many things to obtain satisfactory products in the recent welding industry.


Alloy Digest ◽  
1977 ◽  
Vol 26 (2) ◽  

Abstract SAF 1039 steel can be used in the hot-rolled, normalized, oil-quenched-and-tempered or water-quenched-and-tempered condition for general-purpose construction and engineering. Its manganese content is a little higher than some of the other standard carbon steels with comparable carbon levels; this gives it slightly higher hardenability and hardness. It provides medium strength and toughness at low cost. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: CS-66. Producer or source: Carbon steel mills.


Alloy Digest ◽  
1996 ◽  
Vol 45 (1) ◽  

Abstract INCO WELD C Electrode is a stainless-alloy electrode especially designed for shielded-metal-arc welding of a broad range of materials, including many difficult-to-weld compositions. It can be used in stainless steels, mild and medium-carbon steels,and spring steels. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on joining. Filing Code: SS-632. Producer or source: Inco Alloys International Inc.


2014 ◽  
Vol 216 ◽  
pp. 151-156 ◽  
Author(s):  
Liviu Bereteu ◽  
Mircea Vodǎ ◽  
Gheorghe Drăgănescu

The aim of this work was to determine by vibration tests the longitudinal elastic modulus and shear modulus of welded joints by flux cored arc welding. These two material properties are characteristic elastic constants of tensile stress respectively torsion stress and can be determined by several non-destructive methods. One of the latest non-destructive experimental techniques in this field is based on the analysis of the vibratory signal response from the welded sample. An algorithm based on Pronys series method is used for processing the acquired signal due to sample response of free vibrations. By the means of Finite Element Method (FEM), the natural frequencies and modes shapes of the same specimen of carbon steel were determined. These results help to interpret experimental measurements and the vibration modes identification, and Youngs modulus and shear modulus determination.


Smart Cities ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 919-937
Author(s):  
Nikos Papadakis ◽  
Nikos Koukoulas ◽  
Ioannis Christakis ◽  
Ilias Stavrakas ◽  
Dionisis Kandris

The risk of theft of goods is certainly an important source of negative influence in human psychology. This article focuses on the development of a scheme that, despite its low cost, acts as a smart antitheft system that achieves small property detection. Specifically, an Internet of Things (IoT)-based participatory platform was developed in order to allow asset-tracking tasks to be crowd-sourced to a community. Stolen objects are traced by using a prototype Bluetooth Low Energy (BLE)-based system, which sends signals, thus becoming a beacon. Once such an item (e.g., a bicycle) is stolen, the owner informs the authorities, which, in turn, broadcast an alert signal to activate the BLE sensor. To trace the asset with the antitheft tag, participants use their GPS-enabled smart phones to scan BLE tags through a specific smartphone client application and report the location of the asset to an operation center so that owners can locate their assets. A stolen item tracking simulator was created to support and optimize the aforementioned tracking process and to produce the best possible outcome, evaluating the impact of different parameters and strategies regarding the selection of how many and which users to activate when searching for a stolen item within a given area.


2016 ◽  
Vol 16 (3) ◽  
pp. 39-42 ◽  
Author(s):  
M. Gucwa ◽  
J. Winczek ◽  
R. Bęczkowski ◽  
M. Dośpiał

Abstract The welding technologies are widely used for design of protection layer against wear and corrosion. Hardfacing, which is destined for obtaining coatings with high hardness, takes special place in these technologies. One of the most effective way of hardfacing is using self shielded flux cored arc welding (FCAW-S). Chemical composition obtained in flux cored wire is much more rich in comparison to this obtained in solid wire. The filling in flux cored wires can be enriched for example with the mixture of hard particles or phases with specified ratio, which is not possible for solid wires. This is the reason why flux cored wires give various possibilities of application of this kind of filler material for improving surface in mining industry, processing of minerals, energetic etc. In the present paper the high chromium and niobium flux cored wire was used for hardfacing process with similar heat input. The work presents studies of microstructures of obtained coatings and hardness and geometric properties of them. The structural studies were made with using optical microscopy and X-ray diffraction that allowed for identification of carbides and other phases obtained in the structures of deposited materials. Investigated samples exhibit differences in coating structures made with the same heat input 4,08 kJ/mm. There are differences in size, shape and distribution of primary and eutectic carbides in structure. These differences cause significant changes in hardness of investigated coatings.


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