Filler Metal Research Articles

A Comparison of Sigma Phase Formation in Solubilized Hyper Duplex Stainless Steel and Super Duplex Stainless Steel Filler Metals

This study focuses on the kinetic analysis of sigma phase formation in filler metal wires on Super Duplex Stainless Steel (SDSS) and Hyper Duplex Stainless Steel (HDSS). Precipitation data reveal that in the solubilized microstructure, sigma phase kinetics are more prominent in SDSS. This increased susceptibility is attributed to the greater number of nucleation sites, which is facilitated by the larger interface area/volume and the higher chromium content in the ferrite. The difference in interface area/volume is significantly more influential in determining kinetics than the composition difference, with nucleation sites playing a central role. The sigma phase transformation in both materials was modeled using the JMAK kinetic law. The JMAK plots exhibit a transition in kinetic mechanisms, evolving from discontinuous precipitation to diffusion-controlled growth. In SDSS, the JMAK values indicate “grain boundary nucleation after saturation,” followed by “thickening of large plates.” In contrast, HDSS values point to “grain edge nucleation after saturation,” followed by “thickening of large needles.” The higher kinetics in SDSS are characterized by a smaller nucleation activation energy of 56.4 kJ/mol, in contrast to HDSS's 490.0 kJ/mol. CALPHAD-based data support the JMAK results, aligning with the maximum kinetics temperature of SDSS (875 °C to 925 °C) and HDSS (900 °C to 925 °C). Therefore, the JMAK sigma phase kinetics effectively describe the experimental data and its dual kinetics behavior, even though CALPHAD-based TTT calculations often overestimate sigma formation.

Microstructure and mechanical property of Zr-4 alloys brazed with Ag–Cu–Ti filler metal

Microstructure and mechanical property of Zr-4 alloys brazed with Ag–Cu–Ti filler metal

Influence of geometric imperfections of flange joints on the fatigue load of preloaded bolts

In an ideal flange joint configuration, the fatigue endurance of preloaded bolts is contingent upon factors such as the magnitude of preload, applied working load, and the geometric dimensions of the flange. However, real-world flanged joints often deviate from this ideal geometry, introducing imperfections that can markedly escalate the fatigue burden on bolts. This study endeavors to simulate the geometric imperfections inherent in a standard DN40 flange and ascertain their impact on bolt fatigue through a combination of empirical measurements and finite element (FE) analysis. The investigation reveals that even minor deviations in flange geometry, such as non-parallelism on the order of 0.03 mm, can exert a considerable influence on bolt fatigue, particularly when the flange gap aligns with the applied eccentric working load (same side). To mitigate the deleterious effects of these imperfections, the proposal and evaluation of employing filler material between the flanges are made. Specifically, it is demonstrated that a thin layer of liquid metal filler (KemisKit Fe21), substantially alleviates the fatigue burden on bolts. Empirical findings illustrate that this corrective measure enhances the fatigue life of bolts by a factor of more than 30 under the highest applied working load condition.

Alloy modification and ultrasonic-assisted milling of wear-resistant alloys with defined surfaces

The reduction of CO2 emissions is closely linked to the development of highly efficient and economical steel components in plant and process engineering. To withstand the high combined corrosive, tribological, thermal, and mechanical stresses, wear-resistant coatings tailored to the application and steel grade are used. In addition to the increasing demand to substitute conventional cobalt alloys with nickel alloys, there is also a growing need for defined or functional surfaces of high integrity. Due to high tool wear, milling operations required to produce the complex geometries of the components are often not economically feasible for SMEs. By means of alloy modification of the filler metals for nickel-based plasma build-up welded wear-resistant coatings and by the use of innovative ultrasonic-assisted milling processes more favourable machinability shall be achieved without reducing the wear protection potential. In this paper, the influence of the microstructure and precipitation morphology adjusted by means of alloy modification on the machinability is investigated. This is done based on a wear protection alloy NiCrMoSiFeB (trade name: Colmonoy 56 PTA) typically used for screw machines, which substitutes conventional CoCr alloys (Stellite). Metallurgical investigations and in-situ measurements of occurring process forces and temperatures at the tool cutting edge during milling as well as subsequent investigations of tool wear and surface integrity allow a detailed analysis and correlation between microstructural properties and machinability. For the cast samples, a clear change in the microstructure and hardness can be seen through the addition of Al, Ti, or Nb. These differences lead to an improvement in the machining process for Nb. Al and Ti cause long-needled or star-shaped precipitations and hardness increases, which lead to higher cutting forces and increased tool wear.

Release of nickel and chromium ions from stainless steel brackets as a result of long-term exposure to commonly used toothpaste

Background: Brackets in fixed orthodontic appliances are mostly made from metal or stainless steel. Maintaining oral hygiene by brushing the teeth with toothpaste during orthodontic treatment is important. One of the ingredients in toothpaste, sodium fluoride, can cause degradation of the stainless-steel surface, which has the potential to corrode or release metal elements. Purpose: the purpose of this study is to describe the Nickel and chromium ion release of stainless-steel brackets against toothpaste use in orthodontic treatment by means of narrative review. Review: The main corrosion products of stainless-steel brackets are nickel and chromium. Toothpaste detergents contain sodium lauryl sulfate, which can cause the release of nickel ions due to the presence of sodium ions, which can trigger redox reactions. In addition, the fluoride content will combine with hydrogen to produce hydrofluoric acid, which can damage the oxide layer on orthodontic wires, resulting in the release of metal ions such as nickel and chromium. The effects of the release of these ions can be carcinogenic, cause hypersensitivity reactions, and cause cytotoxicity. Corrosion causes the dissolution of filler metal, resulting in weakened bracket material and increased friction, leading to delayed tooth movement. Conclusion: Toothpaste can affect the release of nickel and chromium ions in stainless steel brackets in the presence of sodium and fluoride.

17-4 PH Steel Parts Obtained through MEX and PBF-LB/M Technologies: Comparison of the Structural Properties.

The material extrusion (MEX) method utilizing highly filled metal filament presents an alternative to advanced additive metal manufacturing technologies. This process enables the production of metal objects through deposition and sintering, which is particularly attractive compared to powder bed fusion (PBF) technologies employing lasers or high-power electron beams. PBF requires costly maintenance, skilled operators, and controlled process conditions, whereas MEX does not impose such requirements. This study compares research on 17-4 PH steel manufactured using two different commercially available techniques: MEX and powder bed fusion with laser beam melting (PBF-LB/M). This research included assessing the density of printed samples, analyzing surface roughness in two printing planes, examining microstructure including porosity and density determination, and measuring hardness. The conducted research aimed to determine the durability and quality of the obtained samples and to evaluate their strength. The research results indicated that samples produced using the PBF-LB/M technology exhibited better density and a more homogeneous structure. However, MEX samples exhibited better strength properties (hardness).

Ag-based filler metal wetting behavior and brazed joint performance on SLMed Ti/TiB2 substrate

PurposeThis study aims to investigate the wetting behavior of AgCuTi and AgCu filler metals on selective laser melting (SLMed) Ti/TiB2, and to analyze the microstructure and fracture characteristics of SLMed Ti/TiB2/AgCuTi or AgCu alloy/SLMed Ti/TiB2 brazed joints. The wetting behavior of AgCuTi and AgCu filler metals on the selective laser melted (SLMed) Ti/TiB2 has been studied. The analysis of microstructures and fracture characteristics in vacuum-brazed SLMed Ti/TiB2 substrate, using AgCuTi and AgCu filler metals, has been conducted to elucidate the influence of brazing temperature and alloy composition on the shear strength of the brazed joints.Design/methodology/approachBrazing SLMed-Ti/TiB2 in a vacuum using AgCuTi and AgCu filler metals, this study aims to explore the optimal parameters for brazed joints at various brazing temperatures (800°C−950°C).FindingsThe findings suggest that elevated brazing temperatures lead to a more extensive diffusion region in the joint as a result of the partial melting of the filler metal. The joint composition changes from distinct Ti2Cu layer/TiCu layer/filler metal to a-Ti (ss) + ß-Ti (ss)/TiCu. As the brazing temperature increases, the fracture mode shifts from brittle cleavage to ductile fracture, mainly attributed to a decrease in the CuTi within the brazed joint. This change in fracture behavior indicates an improvement in the ductility and toughness of the joint.Originality/valueThe originality of this study lies in the comprehensive analysis of the microstructure and shear strength of vacuum brazing SLMed Ti/TiB2 using AgCuTi and AgCu filler metals.

Optimising thermal conductivity of the epoxy using copper as filler particles for improved performance of cryosorption pumps: An experimental investigation

Fusion reactors are one of the best possible solutions to produce sustainable power. In these reactors, by-product helium needs to be continuously removed as they might react with the fuel (tritium) thereby affecting the reaction kinetics. To achieve the same, clean, vibration free and ultra-high vacuum pumps are used which are also unaffected by external electrical and magnetic fields. Considering these limitations, cryosorption pump is the most effective solution. These pumps remove helium molecules by adsorbing them on a cold adsorbent which is maintained at a low temperature by conducting heat from it to a cryopanel via an adhesive. Hence, there is a need for adhesives with high thermal conductivity (T.C.) and optimum bonding strength (B.S.). Towards this, here, we have mixed two different metallic fillers particles namely silver and copper in the epoxy adhesive in different volume fractions. The thermal conductivity and bonding strength of epoxy-silver and epoxy-copper composite adhesives are measured experimentally at the temperatures of 4 K and 7 K, and the latter is found to be the better option. Thus, epoxy-copper adhesive is selected for the development of the cryosorption pump and subsequent measurement of the helium gas pumping speed to achieve the required favourable conditions.

CORROSION BEHAVIOR OF HRB 400 REINFORCING STEEL WELDING JOINT IN SIMULATED CONCERT ENVIRONMENT BASED ON SVET

Based on SVET technology, the corrosion tendency of HRB400 steel welded joint and its base metal in simulated concrete environment and the influence of corrosion products were studied in this paper. The results show that the microstructure of the weld metal and base metal are ferrite+pearlite, and the microstructure of the heat affected zone is incompletely transformed bainite+ferrite+pearlite. Since the region produces smaller grains and more grain boundaries after welding, it becomes the most prone area for corrosion of welded joints. The addition of Cl– inhibited the passivation of HRB400 steel welded joint in the simulated concrete pore fluid. Through the analysis of Nyquist curve and polarization curve, it was found that under high chloride ion concentration, the base metal is more sensitive to chloride ions compared to welded joints.With the increase of Cl– concentration, the current density in the welded joint area gradually increased, but after reaching the chloride concentration of 0.5 mol/L, the current density tended to be flat. The occurrence of this phenomenon confirms the above conclusion. Further more,through SVET testing of the filler metal, it can be found that the filler metal has good adaptability to the HRB400 welding joint, forming a welding joint with better performance.

Effect of PWHT on microstructure and mechanical properties of welded joint of a new Fe-Ni-based superalloy

In this study, the effect post weld heat treatment (PWHT) on microstructural evolution and mechanical properties of weld metal of HT700P alloy with Inconel 617 filler metal was investigated. After welding, columnar grain, dendritic microstructure and segregation of Mo, Co and Ti elements related to the equilibrium distribution coefficient were observed in the weld metal. The PWHT was conducted in both direct-aging treatment with different time and solution treatment with different cooling methods. The results showed that direct-aging treatment had a limit impact on homogenization of weld metal, while microstructural homogenization and elemental segregation were significantly improved after solution treatment and massive M6C and M23C6 carbides precipitated at the grain boundaries and interdendritic region of weld metal. It was found that the elongation at 700 °C of welded joints after solution treatment was relatively increased, which was related to the decrease of residual stress and the precipitation of Mo-rich carbides at the grain boundaries. The fracture occurred in the weld metal presented interdendritic fracture characteristics, and the fracture mechanism for stress relaxation cracking was the strong grain interior induced by the precipitation of γ′ phase, leading to the stress concentration and nucleation of cavities at grain boundaries. After solution treatment, the creep lifetime of furnace cooling was much greater than that of water quenching. The superior creep properties of furnace-cooled joint could be attributed to the lower residual stress and the migration of carbon element in the fusion line, which inhibited the nucleation and aggregation of cavities in the partially melted zone.

Alternative Metallic Fillers for the Preparation of Conductive Nanoinks for Sustainable Electronics

AbstractThe development of electronics with net zero carbon emissions through more efficient and environmentally friendly materials and processes is still a challenge. Here, alternative chemical synthesis routes of metal conductive nanoparticles, based on biodegradable materials are explored, such as nickel, iron–nickel alloy and iron nanoparticles, to be used, in the long term, as fillers in inks for inject printing. Thus, Ni and FeNi metal nanoparticles of 25–12 nm, forming aggregates of 614–574 nm, respectively, are synthesized in water in the presence of a polyol and a reducing agent and under microwave heating that enables a more uniform and fast heating. Iron nanoparticles of 120 ± 40 nm are synthesized in polyol that limits the aggregation and the oxidation degree. Commercial metal nanoparticles of iron and nickel, are coated with ethylene glycol and used for comparison. The conductivity of nanoparticles when pressed into pellets remains similar for both commercial and synthesized samples. However, when deposited on a strip line and heated, synthesized Ni, FeNi, and Fe nanoparticles show significant conductivity and interesting magnetic properties. It is demonstrated that the nanosize facilitates sintering at reduced temperatures and the capping agents prevent oxidation, resulting in promising conductive fillers for printed electronic applications.

An investigation on tensile shear strength of CMT spot weld-brazing of 5052 aluminium alloy and SS 400 galvanized steel

The main purpose of the research is to investigate the effects of spot weld-brazing variables, such as cold metal transfer (CMT) modes and current, on the tensile shear strength of 5052 aluminium alloy for dissimilar joining to SS400 galvanized steel.The method employed in the study was a 3k full factorial design with three replications. Analysis of variance (ANOVA) techniques were employed to identify the variables that influenced the responses of interest. The response optimiser method displayed which factors affected the variables and their impact on strength. In addition, the response optimiser method was employed to find which factors produced the best value for the response variable. A mathematical model was developed to predict the strength of the joints. An optical microscope (OM) and scanning electron microscope (SEM) were also employed to confirm the microstructure. Energy dispersive spectroscopy (EDS) was used to determine the chemical composition of the microstructure.The strength of the weld-brazing joints was affected by the modes and currents used in the joining process. The weld-brazing mode selection was found to have an impact on strength. The synergic mode was shown to have a strength greater than the CMT pulse and pulse synergic modes. The excess or little weld-brazing current was shown to be unsuitable for the joint. The maximum tensile shear strength value was obtained in the synergic mode with a current of 110 A. The resulting prediction model was evaluated with the newly collected experimental data, and the average per cent error was estimated to be 2.07%. In addition, the reaction layer at the aluminium alloy and steel interface was composed of a Fe(Al, Si)3 phase. The optimal conditions for the spot weld-brazing activities resulted in a larger fracture area, a small contact angle, and excellent weld bead geometry.The prediction accuracy of the model appeared satisfactory. However, the altered chemical composition of the filler metals and substrate materials could impact the findings. It is recommended that the electrical signal waveform be studied during spot weld-brazing, as well as the characteristics of other material joints with various other parameters.The weld-brazing mode and current had no significant effect on the type of interface layer of the joints.It is highly possible that the CMT spot weld-brazing technique could be applied to join other dissimilar materials in order to reduce the joining time, but the filler metal chosen must be appropriate.

High temperature and high strain rate properties of brazed honeycomb liner material Haynes 214

Abradable honeycomb sealing systems are essential for gas turbine efficiency. Experimental data on the rubbing performance of Haynes 214 metal sheets brazed with the nickel-chromium-silicon filler metal BNi-5 is presented. The brazing layer in the double foiled honeycomb sections turned out to have a major impact on rubbing behavior. Damage on the rotor was analyzed with a large chamber scanning electron microscope and energy-dispersive X-ray spectroscopy. The results demonstrate a significant influence of the brazing process on the mechanical properties, especially after exposure to 1000 °C. A hard aluminum nitride phase formed in the brazed metal sheets can cause severe damage to the rotor.

Modified Bitumen Materials from Kazakhstani Oilfield

The oil bitumen BND 90/130, produced at the “LLP SP Caspi Bitum” with the modifier, which consists of copolymer of ethylene with butyl acrylate and glycidyl methacrylate taken in an amount of 0.5–1.6 wt%, and the tire reclaim (4–20 wt%), which is the destructate of mesh elastomers of different chemical nature, was modified; possibility of using the developed bitumen-elastomer binders in road asphalt concrete was justified. Modification of bitumen with a copolymer of ethylene with butyl acrylate and glycidyl methacrylate leads to an improvement in the properties of road bitumen: the softening point, hardness, deformability at low temperatures, elasticity, and adhesion to metal and mineral filler increase. It was shown that ethylene with butyl acrylate and glycidyl methacrylate chemically interacts with the functional groups of bitumen asphaltenes through the epoxy group of glycidyl methacrylate. Analysis of the spectra and group composition indicates an increased content of high molecular weight asphaltenes in the modified bitumen with a slight increase in structuring resins. It has been established that bitumen modified with rubber crumbs of 0.6–1.0 mm in size has high elasticity. The most effective composition of a bitumen-regenerated composite material based on tire reclaim has been determined. In terms of the totality of physicochemical and operational characteristics and comparative cost, the most acceptable is the bitumen-regenerated composition (with a regenerate content of 20%) and is superior in the complex of properties to bitumen modified with an optimal content of ethylene with butyl acrylate and glycidyl methacrylate (1.6%). The technology for modifying bitumen with tire reclaim is less time-consuming, more economically profitable, and environmentally effective, since it utilizes large-tonnage waste of worn-out tires. The resulting bitumen-polymer compositions have a high positive set of properties: softening point, hardness, elasticity, frost resistance, and low-temperature characteristics.

Microstructure and mechanical properties of IN738LC superalloy repaired by wide gap activated diffusion brazing method

In the current study, the effect of the weight percentage of filler and additive powder on the microstructural and mechanical properties of the wide gap activated diffusion brazing process was studied. IN738LC base metal powder and AMDRY BRB filler were used as filler metal for IN738LC superalloy brazing. Subsequently, diffusional heat treatment and aging cycle were used to modify the microstructure and mechanical properties in the restoration structure. Optical microscope and scanning electron microscope were used to identify the phases in the braze area and four-point bending tests were performed to evaluate the mechanical properties of the wide gap. For the sample brazed at 1180 °C for 30 min, heat treated at 1120 °C for 4 h, and aged at 850 °C for 24 h, the porosity and eutectic phases in the brazed area and the diffusion-affected zone maintained as low as possible. Thus, it can be referred to as the optimized sample. The samples containing 40 wt% filler had the optimum mechanical properties at ambient temperature and high temperature. Fractography showed that the place of crack initiation was mainly in the filler metal.

Role of buttering layer composition on microstructural heterogeneity and mechanical properties of Alloy 617 and P92 steel dissimilar welded joints for future Indian AUSC program

Restrictive operating conditions (even exceeding 700 °C) of materials in advanced ultra super critical (AUSC) power plants and the need to minimize manufacturing and maintenance costs require the production of dissimilar metal welded joints (DMW). Significant differences in the physical and chemical properties of welded materials lead to phenomena that reduce the weldability of the metals used and force the search for solutions that limit unfavorable phenomena, e.g., the use of buttering layers. The study presents a comparison of two types of joints with Alloy 617 (UNS N06617) and ferritic P92 (UNS K92460) steel made using Inconel 82 (ENiCrFe-3) and Inconel 617 (ERNiCrCoMo-1) alloys buttering layer and the corresponding chemical composition of filler metals. All areas of the joints made with the gas tungsten arc welding process were subjected to structural investigations (optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) and mechanical tests (microhardness, room and high temperature tensile, and toughness testing). Despite the more complicated welding procedure, sound welded joints were obtained with favorable properties resulting, inter alia, from the reduced thickness of the martensite layer in HAZ of P92 steel and the limited diffusion of alloy components compared to welded joints without the buttering layer. This also resulted in a reduction of the maximum hardness (especially in the case of Inconel 82 buttering—by 15–30 HV0.5 in comparison with Inconel 617 buttering) and an increase in strength while limiting the decrease in plasticity (even 663 MPa tensile strength and 21% of elongation for Inconel 617 buttered joint). Moreover, improved high-temperature performance (approximately 70–100 MPa) of the welded joint following the application of the buttering layer was confirmed. The presented results allow for drawing general conclusions that both proposed welding procedures can be recommended for use in the working conditions occurring at AUSC.

Enhanced mechanical properties of TZM joint brazed at high temperature using Mo-Ni filler metal with Boron addition

Enhanced mechanical properties of TZM joint brazed at high temperature using Mo-Ni filler metal with Boron addition

Friction Welding Processes: A Review

Friction welding is a sort of solid-state welding process that does not use flux, shielding gases, or filler metal; instead, the heat needed to fuse the materials is produced by the friction between two or more objects moving relative to one another. This kind of welding is an alternative to the traditional fusion and adhesive-based welding procedures. The method is reliable, capable of joining materials that would seem hard to join with traditional welding, and suitable for joining both similar and dissimilar materials including wood, steel, aluminum, copper, masurium, nickel, zinc and carbon steel. Friction welding can be carried out by using several techniques including linear, rotary, friction stir, direct drive and inertia welding. Each of these welding techniques is distinct and are named according to the relative motion involved. Although the process varies slightly subject to the type of motion, the procedure is consistent and the resultant joint is comparable with those obtained through conventional welding technique. This study reviews the distinct friction welding processes and specific techniques involved in the process.

Study of the corrosion resistance of high chromium white cast iron welds in the presence of NaOH (30% w/w)

– In the mining industry, specifically in bauxite processing, adverse working conditions demand high mechanical and chemical resistance. For such conditions, the choice of potentially resistant materials, such as high chromium white cast iron (HCr-CWI), is necessary. However, presently, there is no effective recovery of equipment made with HCr-CWI, primarily due to the machining difficulties encountered during the repair process. An alternative recovery method is being developed by the Laboratory of Metallic Materials Characterization at UFPA – LCAM, using electric arc welding with two filler metals: the ER307L stainless steel wire andsa high Mn value wire. Within this context, this study aims to investigate the corrosion resistance of the welded joint obtained with these two filler metals. The base metal (HCr-CWI) was analysed as a reference, alongside the metals generated by the welded joints, ER307L and high Mn. The samples underwent tests involving optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and electrochemical tests for corrosion potential, polarization, and impedance. It was observed that the samples exhibited a similar matrix-carbide structure but with different organization and volumes. However, the electrochemical behaviour in terms of corrosion potential, polarization, and impedance was similar, with very close resultant values: 50 V; 3.53 μA; 0.18 kOhms, respectively. This was supported by the corrosion rate of 0.4mmpy and explained by calculations of Cr and Ni volume, which showed inverse concentration magnitudes among the samples.

Effect of heat input on the microstructure and hardness of AISI 321 stainless steel welds using ER 347 filler metal

Stainless steel is widely used in various fields, one of which is AISI 321, which is used for high-temperature applications because of its high resistance to creep and intergranular corrosion. The type of filler metal and heat input on stainless steel welds play an essential role in determining the microstructure and mechanical properties of the welded joints. The purpose of this experiment was to evaluate the microstructure and mechanical properties of AISI 321 stainless steel welds with variations in heat input. This study is expected to explore the performance of this weld joint, which can be anticipated in relevant fields. The welding method used in this experiment was Gas Tungsten Arc Welding (GTAW) with ER 347 as filler metal. Welding was carried out on three samples with a heat input of 0.92 kJ/mm, 0.64 kJ/mm, and 0.52 kJ/mm, respectively. The tests included tensile strength, Vickers microhardness, and microstructure observations. The tensile test results showed that a fracture occurred in the Base Metal (BM) area, indicating that the strength of the weld joint was higher than that in the BM. The Vickers microhardness test results showed that the Weld Metal's hardness (WM) was the highest, followed by the Heat-Affected Zone (HAZ) and BM. The welding experiment that used three variations in heat input demonstrated that higher heat input lowered the hardness of the weld joint. The microstructure observation results around the fusion line demonstrated the presence of step and ditch structures. The ditch structure indicates intergranular corrosion.