Flux-cored Wire Research Articles

Application of flux-cored wires at surfacing, remelting and in metallurgy

Application of flux-cored wires at surfacing, remelting and in metallurgy

Comprehensive analysis of spatter loss in wet FCAW considering interactions of bubbles, droplets and arc – Part 1: Measurement and improvement

The spatter loss under different welding parameters and in different surroundings was measured and compared. The spatter loss coefficients were calculated via considering the net weight of metal from flux-cored wire. Experiments indicated that the spatters mainly congregated near the weld seam in 5 mm. The congregated spatters seriously influenced the evenness of weld seam and caused weld bead shrinkage and overlap. According to the measured values, the spatter loss coefficients significantly decreased along with the increasing welding current. It was deduced that spatter loss can be effectively improved by elevating the welding current level, in which case droplet transfer mode, droplet transfer resistance and bubble shielding could contribute.

Structural transformations of martensitic class coatings deposited by a flux-cored wire with carbide-boride-nitride doping during tempering

This work examines the influence of tempering regimes on the structure and characteristics of a metal deposited with a high-chromium flux-cored wire of a martensitic class with carbide-boride nitride doping. It is shown that tempering at a temperature of 800 °C provides acceptable for machining values of metal hardness. As a result of the release of the metal with borides, the structure decays with the formation of a ferrite matrix, the amount of eutectics and particles of the strengthening phases decreases, and their microhardness decreases to 358-438 HV for the matrix, to 548-754 HV for the eutectic and to 1071-1174 HV for hardening phases.

Hardening of coatings based on chromium steel alloyed with a complex of boride compounds by quenching

This article explores the effect of quenching regimes on the structure and characteristics of a metal deposited by a high-chromium flux-cored wire of a martensitic class with carbide-boride-nitride doping. We established that quenching from a temperature of 1020 °C provides a hardness in the range of 54-58 HRC. It is shown that the hardening is caused by the formation of a martensitic structure, an eutectic composition based on chromium and iron borides, carboboride, carbide and nitride particles for the most part of chromium and titanium with increased microhardness. The hardness of such a metal practically coincides with the hardness of the metal after surfacing.

Structure and Characteristics of the Metal of the Cr-Ni-Mo-Mn-Si-Ti-Nb System Obtained by Surfacing with a Flux-Cored Wire Alloyed by Boron Carbide

This study explores structure and characteristics of the nickel-chrome steel of the Cr-Ni-Mo-Mn-Si-Ti-Nb-B doping system obtained by surfacing with a flux-cored wire alloyed by boron carbide. It has shown that the deposited metal has a composite structure consisting of a supersaturated with alloyed elements solid solution with an austenite-martensitic matrix and a eutectic component (Mo, Cr, Fe, Nb)2B in the form of sections along the boundaries of former austenite grains. Because of the significant content of ferrite-forming elements in the process of crystallization, a metastable δ-ferrite is formed in the weld metal in the form of differently oriented interlayers between the martensite rails. As a result of aging of such a deposited metal at 500 °C for 2 hours, the metastable ferrite undergoes decay at the interphase boundaries α/δ with the formation of the σ phase, which represents sharpened plates with the size of 300÷550 nm. Moreover, aging leads to hardening of the matrix by finely dispersed carboboride and intermetallic phases (Cr, Mo, Fe, Nb, Ti)23(С,В)6, (Fe, Cr, Si)2(Mo, Ti) и (Ni, Fe)3Ti, causing high levels of hardness and wear resistance. The usage of this wire as a surfacing material allows to increase significantly the operability and reliability of the stop valve parts, which work on abrasion in contact with corrosive medium.

Effect of heat treatment on microstructure and wear resistance of high manganese steel surfacing layer

The high manganese steel surfacing layer was deposited on Q235 steel by flux-cored wire gas shielded welding. The as-welded surfacing layer was heated at 1050[Formula: see text]C and quenched in the water, then was tempered at 300[Formula: see text]C. The microstructure, hardness and wear resistance of as-welded surfacing layer and that after heat treatment were comparatively analyzed. The results showed that compared with the as-welded surfacing layer, a large number of fine carbides dispersed in the austenite matrix for the surfacing layer after heat treatment. Meanwhile, the hardness and wear resistance of surfacing layer were slightly improved. The furrow in the abrasive wear for surfacing layer was shallower. Under the action of work hardening, the hardness of high manganese steel surfacing layer gradually increased while the loss weight decreased with the wear time less than 30 min. The hardness of surfacing layer reached the maximum and the loss weight of wear remained unchanged when the wear time was 30–60 min.

Influence of boron microalloying on the structure and properties of joints welding rolled high-strength steel with a standard yield point of 750 MPa by flux-cored wire

The effect of boron on the structure and mechanical properties of a welded high-strength steel with a standard yield strength of 750 MPa has been studied. The flux-cored wire of grade 48PP-69 has been developed on the basis of results.

The effect of aging on the hardening property of steel G7M3S2AFTYu

Abstract This study explores the effect of aging on the structure and characteristics of the metal of composition G7M3S2AFTYu deposited by flux-cored wire. The best results were obtained at a temperature of 550 °C, maintained for 6 h. It was shown that hardening of steel as a result of aging is due to the release of particles of the intermetallic compounds Fe0.875Mo0.125, Fe0.91Si0.09, V1.98Ti0.02, carbonitride Ti2CN, nitride MnN0.457 and VC carbide. As a result of the experiment, we obtained high values of the metal hardness after aging. Therefore, we recommend this steel for surfacing parts operating under conditions of moderate wear.

Rešenja za materijale za tvrdo navarivanje za visokokvalitetne obloge u aplikacijama habanja I korozije

The protection of machinery and structural components by thermal coatings is of huge economic importance. Each hour of downtime, caused by deficient coatings as a result of wear and corrosion, costs a fortune. Savings by reducing these downtime hours can be achieved by applying optimized functional coatings which show enhanced properties. The main welding processes for applying coatings are GMAW or OA, PTA or Laser, each with their pros and cons. The PTA process can be seen as the intermediate process bridging the low cost, high deposition rate and the expensive but high end Laser. Recently, the PTA and especially the laser process are gaining more attention and market shares. Nowadays the flux-cored wires can be upgraded more and more with for instance complex carbides and achieve coatings similar to the high performance coatings obtained by PTA and Laser welding but at much lower costs. The common problems accompanying the GMAW process: a large heat affected zone and dilution, can be circumvented by using the cold metal transfer (CMT), the AC-GMAW and the GMAW hot wire process, allowing the flux-cored wires to fully deploy their large potential and compete with the welding techniques. The current paper will describe the modern GMAW hot wire process and then deal with innovative materials and process concepts for the high performance flux-cored wire to give a competitive alternative for the PTA process and expensive laser.

РАЗРАБОТКА ТЕХНОЛОГИЧЕСКОГО РЕГЛАМЕНТА НАУГЛЕРОЖИВАНИЯ ЧУГУНА В 30-т КОВШЕ. ЧАСТЬ 1

The results of numerical simulation of the carbonization of low-carbon iron as a by-product of the production of titanium slag for the designed unit ladle-furnace (LF) installation as applied to the conditions of PJSC Zaporizhzhya Titanium-Magnesium Combine are presented. The technological regulations have been developed and a numerical study has been carried out on the carburization of metal in a 30-ton ladle at the LF. For the production of commercial pig iron, associated iron-containing waste is used. The purpose of the work is to identify factors of the influence of out-of-furnace processing on technology optimization. A numerical simulation was performed of the carburization technology of liquid low-carbon (up to 2% carbon) cast iron with lump (fraction up to 50 mm) graphite and coke introduced onto the surface of a ladle bath (excluding slag cover). The material and energy balances of the process were carried out, the properties of carburizing materials were studied, and the diffusion coefficient of carbon in a liquid metal was estimated. The results of studies of the hydrodynamic and thermal conditions in the bucket bath of the LF are estimated from the contour diagrams of the flow rates and temperature fields for different flow rates of argon supplied through the bottom and submerged tuyeres. The optimal fractions of carbon-containing materials were determined. It has been shown that treatment on LF with lump graphite requires a shorter duration (≈ 45%) compared with lump coke. To accelerate the process of diffusion dissolution of carbon, it is necessary to periodically (every 3 portions of 70 kg of graphite and coke) heat the melt to a temperature of 1520-1530 ° C. Injection of powdered graphite and coke contributes to a more efficient absorption of carbon and a decrease in the duration of the process (≈ by 1/3). Research continues in the direction of using flux-cored wire for carburizing cast iron at LF.

Study on Welding Techniques of 316L Lined Bimetallic Pipe

It is well known that welding technique was often a knotty problem for bimetallic lined steel pipes to use widely. A number of failures in secession of weld cracking and weld corrosion had been observed in oil fields in recent years, which seriously disrupted the order of oil and gas production. To solve welding problems of 316L bimetallic lined pipes, works outcome about failure analysis and welding process research were presented in this paper. Failure analysis results confirmed that Welding defects, high hardness regions was the main reasons about failure problems of weld crack while structure design defects of seal weld and bad back-protection effects of flux-cored wire resulted in weld corrosion. Welding defects in the regions of seal weld became the failure source while the high hardness both in the region of seal weld and weld joint formed the crack propagation channel, and therefore both initially contributed to weld cracking. Additionally owing to the structure design of seal weld, liner layer would be heated over and over again during the period of seal weld and then it was not enough to protect CRA layers from being damaged during the period of girth weld. As a result the corrosion resistance in the welding area was reduced to become a weak area. On the basis of failure analysis, further research work was carried out to improve welding performance. Seal weld structure and girth weld process was improved. The difference of welding wires and welding process was analyzed, and their defects were described separately. Results showed that the welding performance welding by ERNiCrMo-3 and supporting technology was more reliable than ATS-F309L and supporting technology, whether seal weld or butt welding. The distribution and value of the hardness could be effectively controlled; Moreover, corrosion resistance performance was also better. Therefore, the seal weld and girth weld conducted by ERNiCrMo-3 and supporting technology was feasible.

Development of flux-cored wire for surfacing of parts operating under conditions of wear

Powder wire for surfacing of abrasive-wearing products of Fe - C - Si - Мп - Cr -Ni - Mo system (type A according to IIW classification) was developed and investigated. Studies in laboratory conditions were performed according to the following scheme: multilayer surfacing of the samples was carried out with preheating of plates up to 350 °C and subsequent slow cooling (after surfacing). Surfacing was made by ASAW-1250 welding tractor with manufactured cored wire in six layers on plates of 09G2S steel. Instead of amorphous carbon, carbon-fluorine-containing dust containing 21 - 46 % Al2O3; 18 - 27 % F; 8 - 15 % Na2O; 0.4 - 6.0 % K2O; 0.7 - 2.3 % CaO; 0.5 - 2.5 % SiO2; 2.1 - 3.3 % Fe2O3; 12.5 - 30.2 % Cgen ; 0.07 - 0.90 % MnO; 0.06 -- 0.90 % MgO; 0.09 - 0.19 % S; 0.10 - 0.18 % P was introduced into the wire. The following powder materials were used as filler: iron powder PZhV1 as per GOST 9849 - 86, ferrosilicon powder FS 75 as per GOST 1415 - 93, high carbon ferrochrome powder F99A as per GOST 4757 - 91, carbon ferromanganese powder FMN 78(A) as per GOST 4755 - 91, PNK-1L5 nickel powder PNK-1L5 as per GOST 9722 - 97, ferromolybdenum powder FMo60 as per GOST 4759 - 91, ferrovanadium powder FV50U 0.6 as per GOST 27130 - 94, cobalt powder PC-1U as per GOST 9721 - 79, tungsten powder PVN as per PS 48-19-72 - 92. Studies of the deposited layer have shown that within the obtained limits, carbon, chromium, molybdenum, nickel, manganese and to a lesser extent vanadium simultaneously increase hardness of the deposited layer and reduce rate of wear of the samples. Increase in concentration of tungsten increases hardness of the deposited metal but reduces wear resistance. Low viscosity of matrix does not allow tungsten carbides to be kept on surface, as a result, wear occurs not according to the uniform surface abrasion scheme, but is reasoned by pitting high-strength carbide particles from the matrix, resulting in additional cracks formed in matrix, contributing to additional wear of matrix. Introduction of cobalt to the mixture composition does not have significant effect on hardness and abrasive wear of the deposited layer, which is associated with obtaining more viscous, but less solid matrix. In case of absence of solid particles of carbides embedded in matrix, the effect of introduction of cobalt is negative. According to the results of multivariate correlation analysis, dependences of hardness of the deposited layer and its wear resistance on mass fraction of elements included in flux-cored wires of the Fe - C - Si - Mn - Cr - Mo - Ni - V - Co system were determined.

Hardfacing material solutions for high performance coatings in wear and corrosion applications

The protection of machinery and structural components by thermal coatings is of huge economic importance. Each hour of downtime, caused by deficient coatings as a result of wear and corrosion, costs a fortune. Savings by reducing these downtime hours can be achieved by applying optimized functional coatings which show enhanced properties. The main welding processes for applying coatings are GMAW or OA, PTA or Laser, each with their pros and cons. The PTA process can be seen as the intermediate process bridging the low cost, high deposition rate and the expensive but high end Laser. Recently, the PTA and especially the laser process are gaining more attention and market shares. Nowadays the flux-cored wires can be upgraded more and more with for instance complex carbides and achieve coatings similar to the high performance coatings obtained by PTA and Laser welding but at much lower costs. The common problems accompanying the GMAW process: a large heat affected zone and dilution, can be circumvented by using the cold metal transfer (CMT), the AC-GMAW- and the GMAW hot wire process, allowing the flux-cored wires to fully deploy their large potential and compete with the welding techniques. The current paper will describe the modern GMAW hot wire process and then deal with innovative materials and process concepts for the high performance flux-cored wire to give a competitive alternative for the PTA process and expensive laser.

Effect of simultaneous addition of ferroniobium and ferrotitanium on properties of hardfacing

ABSTRACTThe slag-free self-shielded flux-cored wire with simultaneous addition of ferroniobium (Fe-Nb) and ferrotitanium (Fe-Ti) was developed to fabricate the iron-based hardfacing alloys. The transfer coefficients of Nb and titanium of slag-free self-shielded flux-cored wire were 91.2 and 63.8%, respectively. The changes in microstructures indicate that Nb and Ti addition shifted the carbon concentration in the remaining liquid to one corresponding to the near eutectic state owing to the formation of (Nb, Ti)C which consumed carbon. The wear loss of the hardfacing alloy with 18 wt-% Fe-Nb and 6 wt-% Fe-Ti addition was the smallest among all the alloys owing to the formation of reinforced uniform quadrangle-shaped (Nb, Ti)C carbides in the refined microstructure and the highest hardness.

Slag characterisation of 308L-type stainless steel rutile flux-cored wires

The behaviour of the weld characteristic of flux-cored wires is strongly influenced by the flux. The weld metal and weldability are determined by the flux composition and to a much smaller level by shielding gas used as well. The wide variety of components combined with the complexity of the welding process result in intricate mechanisms occurring in the slag. The slags of the different rutile flux-cored wires, designed for either position or standard downhand welding, were analysed in order to gain knowledge about the complex slag mechanisms and to carry out a metallurgical characterisation. Chemical analysis, differential thermal analysis and microstructural investigations of the slags were conducted to identify and characterise the formed phases. In addition, the viscosities of the slags were measured and correlated with the DTA results.

Alternative PWHT to Improve High-Temperature Mechanical Properties of Advanced 9Cr Steel Welds

Fil: Burgos, Ariel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Tecnologias y Ciencias de la Ingenieria "Hilario Fernandez Long". Universidad de Buenos Aires. Facultad de Ingenieria. Instituto de Tecnologias y Ciencias de la Ingenieria "Hilario Fernandez Long"; Argentina

Improving the quality of layers deposited on rolling rolls by optimising the composition of flux-cored wires

ABSTRACTExperiments were carried out to investigate the effect of adding carbon–fluorine compounds (the waste from metallurgical production) and nickel powder to the composition of flux-cored wires of the C–Si–Mn–Cr–W–V and C–Si–Mn–Cr–V–Mo alloying systems. The results show that the addition of these compounds to the composition of the charge for producing the wires of the 35V9Kh3SF and 25Kh5FMS types improves a large number of the characteristics of the deposited layer: reduces the extent of contamination with non-metallic inclusions, increases the hardness of the deposited layer, refines austenite grains and results in the formation of fine-dispersion carbides which in practice may improve the thermal resistance of rolling rolls, and also prevents the formation of a ferrite network which may have a beneficial effect on cracking resistance. The experimental results can be used to develop new compositions of flux-cored wires for hardfacing rolling rolls protected by Russian Federation patents. The hardfacing technologies of the rolls using these flux-cored wires with the C–Si–Mn–Cr–W and C–Si–Mn–Cr–V–Mo alloying systems are now produced by the ElSib company.

Flux-Cored Wire for the Surfacing of Parts Subject to Wear

Flux-cored wire of Fe–C–Si–Mn–Cr–Ni–Mo composition (type A in the International Institute of Welding classification) is developed for the surfacing of abrasively worn parts. In the laboratory, multiple surface layers are applied to plate samples, with preliminary heating to 350°C and subsequent (after surfacing) slow cooling. An ASAW-1250 welding tool with the new wire is used for surfacing: six layers are applied to a 09Г2С steel plate. Instead of amorphous carbon, the wire consists of dust containing carbon and fluorine, with the following composition: 21–46% Al2O3, 18–27% F, 8–15% Na2O, 0.4–6.0% K2O, 0.7–2.3% CaO, 0.5–2.5% SiO2, 2.1–3.3% Fe2O3, 12.5–30.2% Ctot, 0.07–0.90% MnO, 0.06–0.90% MgO, 0.09–0.19% S, and 0.10–0.18% P. The filler is a powder: PZhV1 iron powder (State Standard GOST 9849–86); FS75 ferrosilicon powder (State Standard GOST 1415–93); FKh900A high-carbon ferrochrome powder (State Standard GOST 4757–91); FMn78(A) carbon ferromanganese powder (State Standard GOST 4755–91); PNK-1L5 nickel powder (State Standard GOST 9722–97); FMo60 ferromolybdenum powder (State Standard GOST 4759–91); FV50U0.6 ferrovanadium powder (State Standard GOST 27130–94); PK-1U cobalt powder (State Standard GOST 9721–79); and PVN tungsten powder (Technical Specifications TU 48-19-72–92). Analysis of the applied layer shows that, within the ranges studied, carbon, chromium, molybdenum, nickel, manganese and, to a small extent, vanadium both increase the surface hardness and slow sample wear. Increasing the tungsten concentration somewhat increases the surface hardness but decreases the wear resistance. The low ductility of the matrix prevents the retention of tungsten carbides at the surface and so, rather than uniform surface wear, what is observed is crumbling of strong carbide particles from the matrix, with the formation of cracks that facilitate additional wear. The introduction of cobalt in the batch does not markedly affect the hardness and surface wear: the matrix obtained is more ductile but less hard. With no hard carbide particles in the matrix, the introduction of cobalt is deleterious. Multifactorial correlation analysis yields dependences of the hardness and wear resistance of the applied layer on the content of elements in the Fe‒C–Si–Mn–Cr–Mo–Ni–V–Co flux-cored wire.

Physical and technical fundamentals of technology used to increase the wear resistance of working surfaces of large volume excavator buckets

Structural-phase states and tribological properties of the wear-resistant coating formed by electric arc surfacing with flux-cored wire on the low-carbon steel Hardox 450, used to protect large volume excavator buckets, are established.

Effect of Boron Microalloying on the Structure and Properties of a Welded Joint Made of a Flux-Cored Wire for Welding of Flat-Rolled High-Strength Steel Plates with a Standard Yield Stress of 750 MPa

Abstract—The effect of the boron microalloying on the structure and mechanical properties of a weld of high-strength steel with a standard yield stress of 750 MPa has been studied. On the basis of the results, a flux-cored wire of brand 48PP-69 has been developed.