Flux-cored Wire Research Articles

Effect of heat input on interfacial microstructure, tensile and bending properties of dissimilar Al/steel lap joints by laser Welding-brazing

Laser welding-brazing technique was used for lap joining of Q235 steel to AA5052 aluminum alloy using a flux-cored Zn-22Al filler wire. The influence of heat input on microstructure, joint strength and bending property of laser Al/steel joints was investigated. The results showed that the types of interfacial intermetallic compounds (IMCs) were kept unchanged with the different laser powers, i.e., Fe2Al5-xZnx phase and FeZn10; while the thickness and morphology of IMC layer changed significantly. This was mainly ascribed to the large increase of the interfacial temperature with the rising laser power, which led to an intensified diffusion reaction. The fracture load first increased and then reached a plateau with the increasing laser power. However, the laser power had very limited influence on the joint bending property because of the formation of dispersed tough FeZn10. Numerical simulation indicated that the interfacial temperature along the interfacial region varied, decreasing from the weld root to weld toe. The peak temperature increased by 700 ℃ and liquid–solid reaction time increased 3.41 s with the increased laser power, which was responsible for the change of IMCs layer.

Effects of High Carbon Ferrochrome Additions on the Microstructure and Properties of Fe-C-Cr-Nb Hardfacing Alloys

Fe-Cr-C-Nb hardfacing alloys composed of 1.07-1.33 wt% C, 0.08-2.61 wt% Cr, and 4.55-4.98 wt% Nb were prepared on C45E4 steel surfaces using alloy steel flux-cored wires. The alloy microstructures were studied by optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) and the effects of the alloying elements on the hardfacing properties were determined. The results indicate that these alloys contain martensite, austenite and NbC phases. As the C，Cr and Nb mass fraction in the surfacing material increases, the austenite and NbC contents increase, and the martensite content decreases. The NbC crystallite size in the surface layer affects its hardness and thus its wear resistance. The wear resistance first increases and reaches to its maximum value which is 5.7 times higher than that of the C45E4 steel substrate, while by higher increasing of the mentioned elements, it decreases.

Influence of the wire diameter and particle fraction of Fe-Al2O3/ZrO2 flux-cored wires processed by wire arc spraying on the abrasive wear properties of the coating

The embedding of ceramic particles of a certain size and concentration in a ductile matrix is a strategy for producing wear-resistant coatings. In wire arc spraying, flux-cored wires with a metallic sheath and particle-filled core can be used for this purpose. The influence on wear properties of wire diameter and particle fraction has hardly been investigated so far. Due to the high kinetics of arc and gas flow, there are considerable challenges with regard to reproducibility, homogeneity and material efficiency. As a basis for a significantly improved understanding of the process, the relationships between the wire diameter, the particle fraction used and the wear resistance of the produced coatings have been investigated. The objects of investigation were flux-cored wires with an iron sheath and a particle filling of Al2O3/ZrO2. By using the ball-on-disc test and rubber wheel test, the wear resistance of the respective coatings was investigated.

Application of Taguchi method and ANOVA analysis for optimization of process parameters and exothermic addition (CuO-Al) introduction in the core filler during self-shielded flux-cored arc welding

The main factors affecting the mechanical properties of the deposited metal in arc hardfacing are primarily the chemical composition and the cooling rate. The latter depends on the filler materials composition, hardfacing condition (mode), and hardfacing technology, determining the geometric parameters and parameters of the welded bead shape, the amount of deposited metal dilution with the base metal, and the amount of the introduced heat. The goal of this work is to analyze the effect of exothermic addition introduction to the core filler and the effect of welding condition on weld bead morphology, thermal indicators, and mechanical properties of the deposited metal. The deposited metal of the Fe-C-Cr-Cu-Ti-V-Al alloying system was used. The Taguchi technique was adopted as the experimental plan design, as follows: the orthogonal array L9 (3 ^ 4) and signal-to-noise ratio (S/N). The analysis of variance (ANOVA) was also applied for determination of the variables contribution to the dependent parameters. Application of the Taguchi method is simpler, more efficient, and quicker. It requires fewer experiments to determine the optimal values of the studied variables. Microstructural studies using an optical microscope were additionally performed for individual samples of the weld metal with the best mechanical properties, for each of the experimental flux-cored wires. We determined that introduction of CuO-Al exothermic addition of to the core filler had a significant effect on such indicators of the weld bead morphology as the weld reinforcement height and the weld reinforcement form factor (WRFF). Introduction of exothermic addition (CuO-Al) to the core filler had a significant effect on the welding current (I), heat input rate (HIR), and microhardness. The arc voltage (Р(Ua) = 45.8 %) had the greatest influence on the microhardness value, while the percentage of exothermic addition in the core filler (P (EM) = 26.9%) and the wire feed rate (P (WFS) = 21.5%) had a smaller effect. It was shown that it is important to take into account complex parameters, such as dilution variation and weld reinforcement form factor (WRFF) for the geometric characteristics of the weld bead and heat input rate (HIR) for heat indicators in order to optimize hardfacing conditions and composition of the core filler (introduction of exothermic addition). According to the results of the article, the value is the most correlated with the average values of microhardness.

Mathematical Analysis of the Influence of the Flux-Cored Wire Chemical Composition on the Electrical Parameters and Quality in the Underwater Wet Cutting

Abstract The paper presents research in the field of underwater wet cutting with the use of flux-cored wires in order to improve the quality and performance. The research has resulted into the development of gas and slag systems for flux-cored wires and determination of, optimal parameters for cutting stability and quality. The underwater wet cutting mechanism is a cyclical process with the formation of periodic keyholes in metal, and it consists of operating and idle cycles. Efficiency of the cutting process can be determined by analyzing cycle times, welding current, voltage, power and a number of short circuits. To assess the stability and efficiency of the underwater wet cutting process, the authors have developed the method for analyzing oscillograms to calculate the probability density of current, voltage and power. To determine the quality of cutting, the authors have provided a criterion based on the ratio of the voltage probability density in the idle and operating cycles.

Розробка порошкових дротів нового покоління для електродугового зварювання в середовищі захисного газу з’єднань низьколегованих сталей з межею міцності 640…940 МПа

Розробка порошкових дротів нового покоління для електродугового зварювання в середовищі захисного газу з’єднань низьколегованих сталей з межею міцності 640…940 МПа

Development of new generation flux-cored wires for gas-shielded arc welding of joints of low-alloy steels with ultimate strength of 640–940 MPa

Development of new generation flux-cored wires for gas-shielded arc welding of joints of low-alloy steels with ultimate strength of 640–940 MPa

Welding fume nanoparticles from solid and flux-cored wires: Solubility, toxicity, and role of fluorides

Welding fume particles are hazardous. Their toxicity likely depends on their composition and reactivity. This study aimed at exploring the role of sodium or other fluorides (NaF), which are intentionally added to flux-cored wire electrodes for stainless steel welding, on the solubility (in phosphate buffered saline) and toxicity of the generated welding fume particles. A multi-analytical particle characterization approach along with in-vitro cell assays was undertaken. The release of Cr(VI) and Mn from the particles was tested as a function of fluoride solution concentration. The welding fume particles containing NaF released significantly higher amounts of Cr(VI) compared with solid wire reference fumes, which was associated with increased cytotoxicity and genotoxicity in-vitro. No crystalline Na or potassium (K) containing chromates were observed. Cr(VI) was incorporated in an amorphous mixed oxide. Solution-added fluorides did not increase the solubility of Cr(VI), but contributed to a reduced Mn release from both solid and flux-cored wire fume particles and the reduction of Cr(VI) release from solid wire fume particles. Chemical speciation modeling suggested that metal fluoride complexes were not formed. The presence of NaF in the welding electrodes did not have any direct, but possibly an indirect, role in the Cr(VI) solubility of welding fumes.

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

Due 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.

Titanium effect on the microstructure and properties of the layer deposited by Fe-C-Si-Мn-Сr-Mo-Ni flux cored wire on the parts working in severe wear conditions

The study results of the structure and properties of the layer deposited with flux-cored wires of the Fe-C-Si-Mn-Cr-Mo-Ni system additionally alloyed with titanium are presented. Surfacing with the investigated flux-cored wires was carried out on a substrate made of 09G2S steel using silicomanganese slag flux.

Infl uence of titanium introduction into fl ux-cored wire of the FE—C—SI—МN—СR—MO—NI system on the parameters of hardening surfacing

Samples of flux-cored wire samples based on the Fe—C—Si—Мn—Сr—Mo—Ni system by adding different amounts of titanium powder, or submerged-arc surfacing from slag obtained during the production of silicomanganese. The data on the microstructure of surfacing and the presence of non-metallic inclusions in them are presented. The results of studies of the dependence of hardness and wear resistance of deposited layers on the percentage of titanium are shown and the corresponding correlation models are presented.

Non-destructive testing of residual stresses during underwater wet welding of shipbuilding steel using flux-cored wire

Non-destructive testing of residual stresses during underwater wet welding of shipbuilding steel using flux-cored wire

Weld Metal Dendritic Structure Modification by Dispersed Refractory Oxide Particles

The paper deals with the modification effect of dispersed oxides particles (Al2O3, MgO, ZrO) on the dendrite structure in low-alloy weld metal. The flux-core wire 1.6 mm diameter for inoculating of oxides powder to weld pool was purposed. Obtained results confirmed an influence of inoculated refractory oxides on dendrites size and morphology, microstructure and mechanical properties of the weld metal.

Influence of introduction of titanium into the composition of a powder wire of type 25X5FMS

The effect of titanium introduction on the microstructure and physical and mechanical properties of metal deposited with flux-cored wire 25X5FMS has been studied. Surfacing of the investigated samples was carried out using a flux made from crushed slag produced by silicomanganese. The microstructure and non-metallic inclusions in the deposited layer have been studied. It is shown that with an increase in the concentration of titanium in the deposited metal, the hardness increases and the wear decreases.

Microstructure, Toughness and Hardness of a Simulated HAZ in Steel S1100QL and of the HAZ of an Actual MAGWelded Joint Made Using a Metallic Flux-Cored Wire

Simulation tests discussed in the article involved structural steel S1100QL having a yield point of more than 900 MPa. The simulations included single (Tmax = 1250°C) and double welding thermal cycle (Tmax = 1250°C + 600°C, Tmax = 1250°C + 760°C and Tmax = 1250°C + 900°C) as well as cooling times t8/5 = 3, 5 and 10 s. Specimens with the simulated heat affected zone (HAZ) were subjected to impact strength tests performed at a temperature of -40°C and +20°C, Vickers hardness tests (HV10) and microscopic metallographic tests (involving light microscopy). Test results were presented in diagrams and photographs. Related comparisons included results of the structural, hardness and toughness tests of simulated HAZs with analogous results obtained during the actual repair welding of a MAG-welded joint made of steel S1100QL. The final part of the article contains discussion concerning the test results and the statement concerning the obtainment of the significant conformity of the phase composition and the morphology of the microstructure as well as the average hardness values of the HAZ areas obtained in the simulations and those of the HAZ area obtained in the actual welded joint. In relation to all tested simulation variants, the impact energy of the simulated HAZ area of steel S1100QL satisfied the minimum criterion of KV = 27 J both in relation to a test temperature of -40°C and that of +20°C. The number of repeated (1 through 4) thermal cycles having preset parameters did not trigger explicitly noticeable changes in impact energy values as regards the simulated HAZ of steel S1100QL.

Study on bonding properties between arc surfacing layers and 1045 steel substrate using pull-lift test method

Three kinds of surfacing layers of the austenitic steel, niobium alloyed steel and hypereutectic high chromium alloyed cast iron were prepared on 1045 steel substrate by arc surfacing process with self-shielding flux-cored wires. The bonding strength between surfacing layers and the substrate was tested by pull-lift test method. The experimental results show that the bonding strength between austenitic steel surfacing layer and the substrate is the highest up to 549.1 MPa, and the fracture location is near the fusion line with quasi-cleavage fracture characteristic. The bonding strength between the surfacing layer of niobium alloyed steel and the substrate is 314.4 MPa and the fracture mainly occurred at the bottom of the surfacing layer, which also presents quasi-cleavage characteristic. While the bonding strength between hypereutectic high chromium alloyed cast iron surfacing layer and the substrate is as low as 170.7 MPa and the specimen ruptures along the fusion line with brittle fracture characteristic. The bonding properties between surfacing layers and the substrate are directly related to the compositions and microstructures near the fusion line.

Features of formation of the structure and proper-ties of surface layers reinforced with flux-cored wires based on the Fe-Ti-B-C system

In this work it was established that the structure of surfacing materials based on the Fe-Ti-B-C system depends on the brand of powders that were used for production of flux-cored electrodes. Two experimental electrodes of Fe-Ti-B-C were studied using two different brands of Ti powders. The brands were PHT and PTM, that are obtained by various methods. Microstructure of the coating with PHT Ti are characterized with the structure without hard TiB2 and TiC phases, which is a proof of the absence of “in-situ” synthesis reaction during FCAW surfacing. Such structure is also characterized by low hardness. Microstructure of the coating with PTM Ti consist of uniformly distributed hard phases in metal matrix, which is a proof of “in-situ” synthesis reaction during FCAW surfacing. The hardness of such structure is higher than the hardness of the previous example. The experiment shows that using powders of different brands can significantly affect the structure and physical and mechanical properties of the surfacing.

Effect of structure and phase composition on wear resistance of economical alloyed metastable and secondary hardening steels of Cr-Mn-Ti system

Problem. Despite a large number of studies in the field of assessing the causes of hot and cold cracks in the surfacing of wear-resistant surfacing alloys, today the issues of developing relatively inexpensive alloyed wear-resistant surfacing materials and the technology of their application remain relevant. Purpose. The purpose of this work is to study the effect of structure and phase composition on the wear resistance of economically alloyed metastable austenitic and secondary-hardening steels of the Cr-Mn-Ti system, additionally alloyed with Mo, B, V. Methodology. Metastable austenitic, martensitic-austenitic and secondary-hardening steels of the Cr-Mn-Ti system additionally alloyed with Mo, V were investigated. Mechanized surfacing was carried out with alloyed flux-cored wires under fluxes AN-22 and AN-20 with the supply of a de-energized filler flux-cored wire to the head of the welding pool. The use of surfacing with a de-energized flux-cored wire made it possible to reduce the proportion of the base metal in the deposited metal, to reduce the specific consumption of electricity and flux, and to increase the assimilation of alloying elements in the deposited metal. Manual arc surfacing was performed with a CaF2-coated flux-cored wire electrode and a de-energized flux-cored wire in a copper die. Automatic submerged arc surfacing was carried out in the following modes: IN = 300 ... 350 A, UD = 26 ... 30 V, q = 6 ... 10 kJ / cm, with manual surfacing: IN =180 ... 220 A, UD = 25 ... 28 V. Results. The studies carried out confirm the possibility of the formation of a "white band" both in alloys with a high concentration of elements - austenizers (Mn, C, Ni), and when alloying with carbide-forming elements with a relatively low affinity for carbon. (V, Mo). The indicators of resistance to cracking (КС, j-integral, δС), and, consequently, resistance to wear, of secondary hardening martensitic steels are higher than of metastable and tool steels.

Development of a new flux-cored wire based on the gas cleaning dust of the silicomanganese

ABSTRACT The possibility of producing flux-cored wire by using gas-cleaning dust of the silicomanganese production and gas-cleaning dust of aluminium production with a different ratio of components is studied. As components are used: gas cleaning dust of aluminium production, wt. %: Al2O3 = 21–46,23; F = 18–27; Na2O = 8–15; K2O = 0.4–6; CaO = = 0.7–2.3; Si2O = 0.5–2.48; Fe2O3 = 2.1–3.27; Ctotal = 12,5–30,2; MnO = 0.07–0.9; MgO = 0.06–0.9; S = 0.09–0.19; P = 0.1–0.18 and the dust of gas cleaning silicomanganese, wt. %: Al2O3 = 2.43; Na2O = 1.32; K2O = 5.56; CaO = 6.4; SiO2 = 29.19; BaO = 0.137; MgO = 7.54; S = 0.23; P = 0.04; Fe = 1.067; Mn = 27.69; Zn = 2,687; Pb = 3.833. The deposition is performed under a flux made from a slag of silicomanganese produced by the West-Siberian Metallurgical Plant with the chemical composition: Al2O3 = = 6.91–9.62%, CaO = 22.85–31.70%, SiO2 = 46.46–48.16%, FeO = 0.27–0.81%, MgO = 6.48–7.92%, MnO = 8.01–8.43%, F = 0.28–0.76%, Na2O = 0.26–0.36%, K2O = 0.6–2%, S = 0.15–0.17%, P = 0.01%. The deposition mode is selected. The samples wear tests carried out on the machine 2070 SMT-1. The chemical composition of the deposited metal is determined by the X-ray fluorescence method on an XRF-1800 spectrometer and the atomic emission method on a DFS-71 spectrometer. The hardness of the deposited layers is measured through the use of the MET-DU hardness tester. Evaluation of non-metallic inclusions was carried out according to GOST 1778–70 through the use of the optical microscope OLYMPUSGX-51. The principal possibility of manufacturing flux-cored wires for wear-resistant deposition through the use of the gas cleaning dust of the production of silico-manganese and gas cleaning of aluminium production with a different ratio of components is shown. Qualitative indicators are studied, and the manganese absorption coefficients for various ratios of components are calculated. Statistical processing of research results is carried out; statistical dependencies of the component composition effect on the properties of the deposited layer are constructed.

Hardfacing of Copper

The article discusses the primary issues of the hardfacing of copper elements exposed to intense abrasive wear, gas-abrasive wear at high temperature and in contact with liquid metal. In addition, the article presents test results concerning the surfacing of copper grade M1 performed using a self-shielded flux-cored wire providing weld deposit Fe14 and plasma powder surfacing performed using powder providing weld deposit Ni3 (in accordance with EN 14700).