Nickel base hardfacing alloys serve to mitigate corrosion losses at elevated temperatures. Efficacy of Nickel base hardfacing alloys can be compromised when applied onto Fe base substrates due to ...iron dilution in hardfacing. The degree of Fe dilution can be reduced by using advanced deposition methods and optimized deposition parameters. Gas Tungsten Arc Welding (GTAW) method is commonly employed for its cost-effectiveness and versatility, but it tends to induce higher Fe dilution due to increased heat input. This study aims to reduce the degree of Fe dilution and enhance corrosion resistance by introducing a nickel base buffer layer (alloy 625) between the nickel base hardfacing alloy and AISI 316L stainless steel substrate. For comparative purposes, Ni base hardfacing alloy was deposited on the substrate without any buffer layer. Hardfacing depositions were prepared using manual GTAW process. Process parameters namely, deposition current, voltage, travelling speed, pre-heating temperature, and cooling method were kept constant. Samples underwent aging at 1123 K for 4 h, followed by microstructural examination via optical and scanning electron microscopes. Iron (Fe) dilution quantification was performed using energy dispersive spectroscopy (EDS). The EDS analysis showed that the use of buffer layer between the hardfaced deposit and the substrate decreased the degree of Fe dilution in the hardfaced deposit. X-Ray diffraction (XRD) analysis was performed to identify various phases formed in the hardfaced deposit. Potentiodynamic polarization test was performed to assess the corrosion resistance of hardfaced deposit in 3.5 wt% NaCl solution. Results show significant improvement in corrosion resistance of hardfacings deposited sample with buffer layer as compared to those without buffer layer. Aging treatment further enhanced corrosion resistance. The corrosion resistance data is correlated with the microstructure and phases formed in various samples.
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•The impact of buffer layer on hardness, microstructure, Fe dilution, and corrosion resistance in Ni-based hardfacing using the GTAW method.•Higher Ni concentration in the hardfacing deposition reduces Fe dilution, improving the Ni/Fe ratio in Ni-based hardfacing.•Presence of Mo and Nb in the hardfacing refine microstructure and improve corrosion resistance.•Solidification analysis performed to assess the impact of Mo and Nb addition using phase and Scheil diagrams.
The conventional Fe–Cr–C overlay is studied due to the lack of information regarding the response of this material system to impact wear conditions. Previously the same material system has been ...successfully used in erosion wear conditions. The high stress abrasive impact wear resistance and low and high surface fatigue wear behaviour of a Fe–Cr–C overlay (FeCrC—matrix) produced by plasma transferred arc welding (PTA) were studied.
The overlays with varied PTA hardfacing process cooling parameters were tested. The cooling parameters were as follows: (1) active cooling—application of gas cooling of substrate during the welding process; (2) passive cooling—application of copper plate under substrate with constant temperature of 20°C and (3) standard—cooling in the air. Different cooling time leads to differences in microstructure and formation of residual stresses (surface cracks, etc.).
The abrasive impact testing reveals the difference in the overlays response to the cyclic stressing at high impact energy. The surface fatigue wear (SFW) testing is accompanied by the abrasive impact wear (AIW) testing. The SFW incorporates cyclic loading of the overlays surface with spherical indenter with radius of 10mm at high loads, while in AIW testing the specimens are bombarded almost in normal direction with granite gravel particles (diameter of <6mm) with the energy in the range of 0.14–0.52J.
The study proposes the relation between high energy impact/abrasive wear behaviour and the surface fatigue wear behaviour of Fe–Cr–C hardfacings produced under varying cooling conditions.
Ni-Cr-B-Si alloy is used for hardfacing of 316LN Stainless Steel components in Sodium-cooled Fast Reactors (SFRs) to enhance wear resistance and also to prevent self-welding. Since the shear force is ...acting between the substrate and the deposit due to dissimilar thermal expansion during high temperature operating conditions, it is necessary to focus on the hardfacing process which provides good bonding shear strength between them. Though low substrate dilution is advisable to attain high microhardness of the deposit, the deposit should not get de-bonded due to shear. To seek solution to this problem, three major hardfacing processes, viz., Plasma Transferred Arc, Gas Tungsten Arc and Laser processes were considered. Hardfaed shear specimens were prepared using each process and tested as per the ASTM A264. Faster cooling rate leads to finer grains and higher microhardness. The influence of dilution on the microhardness was studied. Scanning Electron Mircographs and Energy Dispersive Spectroscopic studies at the fractured surfaces were done to ascertain the reason for strength. Finally, the laser hardfacing process which provides a combination of good shear strength, high microhardness as well as low dilution is recommended for hardfacing of the components of the SFRs for their reliable operations.
This article describes the process of modeling the restoration operations of the destroyed segment of the spline and its complete restoration using modern methods, such as hardfacing in a protective ...gas environment with a consumable electrode. The ANSYS Workbench 19.2 software with an additional Welding Distortion and Moving Heat Source extension was used to simulate the process of hardfacing a damaged surface. The thermomechanical behavior of the deposited layer on the outer surface of the splined shaft is analysed. Dependences of the value of temperature fields on the parameters of the hardfacing mode in one and two passes depending on time are established. Dependences of residual stresses (0.413-239 MPa) and deformations (0.02-0.23 mm) in the process of semi-automatic hardfacing are determined. Experimental studies of samples during hardfacing were carried out for comparison with the geometry of the weld during modeling. The simulation results are in good agreement with the experimental data.
A Cu–Ni–Mn alloy based hardfacing coating reinforced by WC particles is deposited on steel substrates by a manual oxy-acetylene weld hardfacing method. Microstructure and wear resistance performance ...of the fabricated hardfacing coatings are investigated. There are no cracks or other defects observed in the hardfacing coating. Uniform distributed WC particles in the composite hardfacing coating are not dissolved, and its volume fraction is up to about 63%. A sound bond is formed at the interface of WC and Cu–Ni–Mn alloy, and the bond between the coating and the steel substrate is reliable. With silica sands, the wear resistance performance of the composite hardfacing coatings is about 4 times better than that of the high-Cr cast iron, and its volume loss presents approximately a linear relationship with the sliding distance. The main wear mechanisms are the plastic extrusion of the Cu–Ni–Mn matrix and the fracturing of WC-reinforcement particles under three-body abrasive wear condition in this paper.
•A WC/Cu–Ni–Mn composite is developed by an oxy-acetylene weld hardfacing method.•WC particles did not dissolve during the weld hardfacing process.•No defects are observed in the composite or at the interface of WC/Cu–Ni–Mn alloy.•The composite is 4 times more resistant against wear than high-Cr cast iron.•Wear mechanisms are the plastic extrusion of the matrix and the fracturing of WC particles.
•Two π-ferrosilicide containing carbon-free iron-based alloys with high hardness were developed.•The presence of ordered D03 precipitates in the ferrite matrix along with the orientation relationship ...between π-ferrosilicide and ferrite matrix provides promising wear properties in these alloys.•The dissolution of π-ferrosilicide at high temperatures enables easy thermomechanical processing of the alloys.
Recently, iron-based alloys with a π-ferrosilicide phase have emerged as potential alternatives to cobalt-based hardfacing alloys. Here, we present the development of two π-ferrosilicide containing alloys: one with a ferritic matrix and the other with a ferritic-austenitic matrix. In the as-cast condition, both alloys revealed fine Ni- and Si-rich coherent cubic shaped D03 precipitates in the BCC matrix. The π-ferrosilicide phase was found to have an orientation relationship with the ferrite phase, nucleating within ferrite matrix and from ferrite grain boundaries. In contrast to carbide-strengthened hardfacing Fe-alloys, here the dissolution of the π-ferrosilicide phase at 1200 °C enables easy thermomechanical processing of these alloys, which results in refinement of the π-ferrosilicide and additional formation of χ-phase precipitates in the ferrite. Nano-scratch tests provided evidence of a resilient silicide-ferrite interface, likely to due to it possessing some coherency. Both alloys also displayed compressive strengths approaching 2 GPa and ductility in compression of approximately 25 %. The combination of processability and attractive mechanical properties suggests that these alloys have the potential to serve as alternatives to carbide-reinforced hardfacing Fe-alloys.
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•Ferroboron powder addition affected abrasive wear resistance positively.•Hard phase morphology has a major effect on wear resistance in addition to hardness.•Increasing FeB in powder mixture ...increased the hardness and the wear resistance.•Increasing boron content promoted the formation of primary hard phases.
The aim of this study is the investigation of the effect of ferroboron and the amount of powder mixture (ferroboron+ferrochromium) on wear resistance of Iron (Fe)–Chromium (Cr)–Carbon (C) based hardfacing alloys. Powder mixture, consisting of ferrochromium (FeCr) and ferroboron (FeB), was added to massive wire during welding process. Hardfaced layers were obtained by three different powder mixtures and two different powder/massive wire proportions. Hardfacing was applied to AISI 1020 steel substrate by open arc welding. Hardness test, Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analysis, dry sand/rubber wheel abrasion test were executed. Test results showed that increasing ferroboron content and increasing powder mixture amount enhanced the wear resistance.
Cold metal transfer (CMT) welding is a new gas metal arc welding process having several advantages such as low heat input and spatter free welding. This makes it of great advantage in weld cladding ...applications. In this study, hardfacing of AISI H13 die steel with Stellite 21 alloy has been carried using CMT process. Coatings were deposited on H13 substrate in annealed as well as quenched & tempered (Q&T) condition at room temperature as well as with a preheat of 400°C. The Q&T substrate with and without preheat and the annealed substrate without preheat were found to be susceptible to underbead cracking upon Stellite deposition. The cracking in the heat affected zone (HAZ) was due to formation of brittle martensite upon rapid cooling which is associated with formation of high tensile residual stresses at the bead toe. The annealed substrate with preheat of 400°C showed the least cracking tendency. The cracking tendency was investigated by studying the variation of the microstructure and microhardness along the depth of HAZ. The dilution levels based on Fe content was found to be 3–4%, which was considerably lower than that of conventional arc welding deposits. The Stellite coated H13 plate (annealed with preheat) could be successfully subjected to quenching & tempering heat treatment to restore the properties of the substrate without introducing any defects.
•Crack free deposition of Stellite 21 requires an annealed H13 with preheat of 400°C.•Formation of brittle martensite layer in HAZ provides easy path for crack propagation.•CMT process results in very low (3–4%) dilution Stellite 21 coatings.•Coated H13 can be heat treated to restore its properties.
Wear resistant welds are used in many industries when it is necessary to protect machine components and structures against wear caused by operating conditions. Often the main parameter determining ...the usefulness of these welds is high hardness reaching about 60HRC. In many cases, after the surfacing process, a mesh of cracks is formed in the surface layer, which can affect the durability of the hard-wearing layers used. The paper presents the analysis of the influence of preheating before welding up to 400 ° C on the properties of welds and its effect on the number of cracks in the surface layer. The use of preheating allowed to reduce the number of cracks in the surfacing to 1. The optimum heating temperature was 200 ° C, for which the number of cracks was reduced and the lowest wear was recorded.
The severe operation conditions of the hot working process lead to premature failure of the hot working tools. The dominant failure of hot working tools is wear of the tool surfaces induced by the ...thermal softening phenomenon. Several researchers related to the service life extension technology of hot working tools paid attention to the protective overlay coating technology, so called hardfacing, for preventing premature wear of the hot working tool. This paper reviewed recent research on the application of hardfacing technology to hot working tools. In addition, the key technology and the state-of-the art of the hardfacing technology related to improvement of the wear characteristics of hot working tools were discussed. Finally, future research issues of the hardfacing technology to enhance the service life and wear characteristics of the hot working tools were described.
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