Hardfacing Layer Research Articles

Investigation of softening in hardfaced layers during welding

Hardfacing is a widely used technique to create wear-resistant layer on the base material to ensure good durability and performance under harsh operating conditions. However, despite its effectiveness in improving wear resistance, hardfaced layers can sometimes exhibit softening phenomena during welding, compromising their mechanical properties and overall performance. In this research, the effect of heat input was investigated in case of Fe-based hardfacing material with high Cr content. 4 different heat inputs were applied with gas metal arc welding and significant differences were determined in hardnesses, which can be influential to the lifetime of hardfaced parts. Hardness drop happens in the heat-affected zones between the hardfaced layers and the highest heat input causing the most significant softening (20% hardness drop).

Selection of a suitable technology for the repair of forged structural steel using surfacing welding method

The article discusses the selection of an appropriate technology for the repair of forged structural steel through the use of hardfacing MMA welding method. Investigated, additionally, is the wear resistance of the hardfacing layers. The method used to determine the wear resistance is "block on ring". The macrostructure, microstructure and Vickers microhardness (HV0.05) were also analyzed.

Hardness and Microstructure Characterization of Hardfacing Alloys Deposited by The Shielded Metal Arc Welding (SMAW) on AISI 1045 Medium Carbon Steel

A ring frame is a machine used for yarn production in the textile industry. Continuous use of the machine results in wear on the shaft timing pulley on the ring frame machine. To improve this condition, repairs are needed, one of which uses the hardfacing method. This study aims to determine the effect of hardfacing on the microstructure and hardness of the shaft timing pulley made from AISI 1045. The hardfacing process used the shielded metal arc welding (SMAW) method with welding current variations of 115 A, 125 A, 135 A, 145 A, and 155 A. In this study, the electrode used was AWS A5.1 E7018 with a diameter of 3.2 mm. The hardfacing product obtained was then finished with a lathe to produce a shaft with a final diameter of 30 mm. In this study, microstructure and hardness tests were carried out on specimens before and after finishing. The results of this study showed that an increase in current caused an increase in the number of pearlite phases in the weld metal and HAZ (heat-affected zone) areas. While in the base metal, the increase in current increased the number of ferrite phases. The highest hardness value was found in specimens that were hardfaced with a current of 145 A. However, the hardness of the hardfacing layer will decrease with the use of currents greater than 145 A. The hardness of the specimens with hardfacing treatment at a current of 145 A resulted in hardness in the weld metal, HAZ, and base metal of 225 HV, 209 HV, and 203 HV, respectively. After the finishing process, the weld metal, HAZ, and base metal in this specimen produced a hardness of 225 HV, 217 HV, and 208 HV, respectively.

Processing of crack-free Nickel- and Cobalt-based wear protection coatings and defined surfaces by subsequent milling processes

In the area of plant engineering, steel components are provided with a wear protection coating for efficient use to protect them against corrosive, tribological, thermal and mechanical stresses. The use of innovative ultrasound-assisted milling processes and plasma-welded nickel- and cobalt-based wear protection coatings are being investigated to determine how more favourable machinability can be achieved while retaining the same wear protection potential. The focus is on the NiCrSiFeB alloy, which is intended to replace CoCr alloys in the area of screw machines. The utilization of ultrasonic-assisted milling for the machining of coating materials is a novel approach. The modification of hard facing layers in terms of microstructure and precipitation morphology as well as suitability for machining is investigated and compared with the CoCr alloy. The alloy modifications are generated by a PTA process by systematically adjusting the preheating and interpass temperatures, a crack-free wear-resistant layer can be generated, which is subsequently machined by a milling process. In addition to the crack-free properties, the microstructure, the bonding as well as the mixing between the NiCrSiFeB alloy and a 1.8550 as well as between the CoCr alloy and a 1.4828 are analysed and compared in the joining areas. In addition, heating and cooling rates are determined and a chemical analysis of the weld metals is performed. Furthermore, it was found that the build-up layers of NiCrSiFeB alloy are more difficult to machine using the milling process than the CoCr alloy, as higher milling forces are required.

Restoration of the Impact Crusher Rotor Using FCAW with High-Manganese Steel Reinforced by Complex Carbides

Abstract A new hardfacing alloy within the Fe-Ti-Nb-Mo-V-C alloying system was utilized to restore the working surfaces of cone crusher rotors using Flux-Cored Arc Welding (FCAW). TiC, NbC, Mo2C, VC, Mn, and ferromanganese powders were selected as the base materials for manufacturing the welding wire. The resulting hardfaced layer exhibits a composite structure, with manganese austenite as the matrix and complex solid solution reinforcements with a NaCl structure, closely resembling the formula (Ti0.3Nb0.3Mo0.3)C. The primary advantages of this hardfacing alloy include its capacity for intensive deformation hardening along with high abrasion resistance. The hardness of the hardfaced layer is approximately 47 HRC in the as-deposited state and increases to around 57 HRC after work hardening, surpassing typical hardfacing alloys derived from high manganese steel by about 10 HRC. The efficacy of the alloy was tested in restoring rotors made of Hadfield steel in a PULVOMATIC series crusher model 1145, during the milling of sand-gravel mixtures ranging from 25 to 150 mm into spalls measuring 5 to 20 mm. With an average productivity of approximately 60 tons per hour and a production volume of 300 tons, the utilization of this hardfacing alloy enabled multiple restorations of the rotor while maintaining productivity at a level of 15 thousand tons of spalls.

An experimental study on the quality of hardfacing layer through resistance seam welding

Shaft-shaped parts work normally in wear-resistant conditions. Over time, the shaft might experience wear and fail to maintain the required size, affecting its workability and efficacy. This study examines the hardfacing layer quality of a restored steel shaft obtained through resistance welding. The researchers of this study designed nine welding conditions according to Taguchi's experimental matrix and applied each to experimentally weld steel shaft samples. A recovery welding machine system, which includes a resistance seam welding machine combined with a designed fixture, was used to weld the samples. The experimental results revealed that the welding layers’ surface is flat and has no surface defects. Meanwhile, the hardfacing layer and the retorted shaft surface have good cohesion, as observed through macrostructure photography. The hardness and wear resistance of the hardfacing layer were relatively high and closely resembled those of a new high-frequency quenched steel shaft. The influence level and the relationship of the welding parameters on hardness and wear resistance were also considered in this study. In addition, this study proposes the appropriate welding conditions for obtaining the highest hardness and the smallest worn metal weight. The findings presented in this study offer valuable insights for mechanical manufacturers engaged in the reconditioning process of shafts, aiding in time and cost savings.

Microstructure and Hardness Characteristics of Swing-Arc SAW Hardfacing Layers.

Hot-rolled backup rolls are widely used in steel rolling and usually need to be repaired by arc hardfacing after becoming worn. However, a corrugated-groove defect commonly occurs on the roll surface due to the uneven hardness distribution in the hardfacing layers, affecting the proper usage of the roll. Accordingly, a new swing-arc submerged arc welding (SA-SAW) process is proposed to attempt to solve this drawback. The microstructure and hardness are then investigated experimentally for both SAW and SA-SAW hardfacing layers. It is revealed that a self-tempering effect occurs in the welding pass bottom and the welding pass side neighboring the former pass for both processes, refining the grain in the two areas. In all the zones, including the self-tempering zone (STZ), heat-affected zone (HAZ), and not-heat-affected zone in the welding pass, both SAW and SA-SAW passes crystallize in a type of columnar grain, where the grains are the finest in STZ and the coarsest in HAZ. In addition, the arc swing improves the microstructure homogeneity of the hardfacing layers by obviously lowering the tempering degree in HAZ while promoting the even distribution of the arc heat. Accordingly, the hardness of the SA-SAW bead overall increases and distributes more uniformly with a maximum difference of < 80 HV0.5 along the horizontal direction of the bead. This hardness difference in SA-SAW is accordingly decreased by ~38.5% compared to that of the SAW bead, further indicating the practicability of the new process.

Abrasive Wear Properties of Wear-Resistant Coating on Bucket Teeth Assessed Using a Dry Sand Rubber Wheel Tester.

Ni60-WC coatings with different WC contents on the bucket tooth substrates were pre- pared using laser cladding technology. Their abrasive wear properties were assessed using the dry sand rubber wheel test system. The substrate and the hard-facing layer were tested for comparison. The results showed that the hardness of the Ni60-WC coatings increased with the increase in WC content. The wear resistance of the bucket tooth substrate was greatly improved by hard-facing and laser cladding Ni60-WC coatings. The wear rate of the hard-facing layer was reduced to 1/6 of that of the tooth substrate. The wear rate of the laser cladding coatings with 20-40 wt.% WC was similar to that of the hard-facing layer. It is worth mentioning that the wear rate of the coatings with 60-80 wt.% WC was only 1/4 of that of the hard-facing layer. Micro-cutting with surface plastic deformation was the main wear mechanism of the substrate to form narrow and deep furrows. The wear mechanism of the hard-facing layer was mainly plastic deformation with a wide groove, and the surface cracks promoted the removal of the material. The removal of the binder phase caused by micro-cutting was the main wear mechanism of the laser cladding Ni60-WC coatings. However, the hard phase of WC hinders micro-cutting and plastic deformation, which improves the wear resistance of the coating.

Investigations of Wear Resistance of Hardfaced Layers on Steel 40X

The article discusses a fundamental problem in the shipbuilding industry related to the repair of critical and expensive components directly related to the operation of ships in the global fleet. Methodology and technology for repair by welding of workpieces made of 40X steel have been developed and applied. Hardfacing electrodes of the brands OK 83.28 and OK 61.20 were used. The developed welding technologies include both buffered and non-buffered layers. For one of the specimens, preheating to a temperature of 200 degrees Celsius was performed, which proved to be optimal for the metal. The measured macro stresses are below the elastic limit of the examined metal. The measured residual stresses are insignificant at +62 MPa. The microhardness results show an increase in microhardness to about 450HV in the weld metal zone. The dry friction wear test performed on the welded layer showed a relatively uniform metal loss in both specimens due to the slight increase in temperature.

The Effect of Fe on the Mechanical Properties of Stellite 6

Stellite 6 is a Co-based alloy with excellent wear and corrosion resistance, resulting in it frequently being used as a hard-facing material. The main defect that occurs in the hard-facing process is the peeling of the hard-facing layer, which is caused by thermal stress due to differences in thermal expansion coefficients. This peeling phenomenon can be prevented by using a material with an intermediate coefficient of thermal expansion as a buffer layer. Component surfaces are strengthened through a technique called hard-facing, which increases the components’ resistance to wear. In order to increase the wear and corrosion resistance of metal components, a high-hardness substance is usually coated onto their surface. Grinding is carried out to smooth the surface after the material is welded onto the base component. Small pieces, also referred to as “scrap”, are frequently produced during this surface machining procedure. In the hard-facing process, scrap containing a mixture of base material and Stellite 6 is generated during material processing. If this scrap can be used as a buffer layer, the cost of raw materials can be reduced through the recycling of resources, and the overall energy consumption for recycling can be reduced because the process of separating Stellite 6 from the scrap is eliminated. In this study, the physical properties of Stellite 6 with Fe added were explored to determine whether the scrap produced could be used as a buffer layer. When iron was added to the mixture, the amount of carbide decreased, in addition to the wear resistance and hardness decreasing. Regarding the thermal expansion coefficient, the thermal expansion coefficient of Stellite 6 was found to be 15.879 μm/m·°C at 300 °C, and that of Stellite 6 with 40% Fe added was found to be 14.313 μm /m·°C at 300 °C. The thermal expansion coefficient of carbon steel is reported to be 12.8 μm /m·°C at 300 °C; thus, Stellite 6 with 40% Fe can be used as a buffer layer for Stellite 6 and carbon steel because of its suitable thermal expansion coefficient.

The Influence of the Hot Working Tool Steel Substrate Material on the Element Distribution, Microstructure and Hardness of Gas Metal Arc Welding Hardfaced Layers

The Influence of the Hot Working Tool Steel Substrate Material on the Element Distribution, Microstructure and Hardness of Gas Metal Arc Welding Hardfaced Layers

Simple but Effective Heat Treatment on Hot Isostatic Press Diffusion Bonded Ni60A Hardfacing Layer

Simple but Effective Heat Treatment on Hot Isostatic Press Diffusion Bonded Ni60A Hardfacing Layer

Analysis of variations in the number of layers of hardfacing overlay ABREX 500 material on hardness,impact strength and microstructure with the SMAW process

Hardfacing is a welding technique that functions to increase the surface hardness value of a material. Generally, hardfacing is done on low-carbon steel materials because low-carbon steel cannot be increased in hardness by heat treatment. For this reason, research will be carried out on the multilayer hardfacing process with the aim of obtaining optimal layer hardness. The methodology in this research is that multilayer hardfacing welding will be carried out consisting of 3 layers, 4 layers, and 5 layers, and each specimen has 2 buffer layer layers with E 309 electrodes for the hardfacing layer using HV 600 electrodes. This research reveals the influence of the number of layers of hardfacing on the hardness and toughness values. ABREX 500 material with a size of 150x150x10 mm was welded using the SMAW process using a current of 130 A. In this research, hardness and toughness tests were carried out. On test results. The base metal microstructure is dominated by a tempered martensite structure with a small amount of bainite and pearlite. In the structural area of the support layer, austenite and vermicular ferrite dominate. In the hardfacing layer area, austenite and vermicular ferrite, which are in dendritic form, dominate. The increase in hardness will occur significantly after hardfacing is carried out on the base metal. In a specimen, the more layers of hardfacing are added, the harder the material will be. The hardness of the specimen in 5 layers gets the most optimal value (higher) when compared with the hardness in 3 layers and 4 layers. In the 5-layer specimen, the resulting hardness value was 482.13 kgf/mm2, for the 4-layer specimen, the average value was 464.83 kgf/mm2, and in the 3-layer specimen, the hardness value was 444.13 kgf/mm2. For toughness testing, the highest toughness value was obtained, namely 1.32 (J/mm2) for the 3 layers specimen, compared to 4 layers with a toughness value of 1.25 (J/mm2) and 5 layer with a toughness value of 1.19 (J/mm2). The toughness value decreases as the hardness value increases.

Experimental study on mechanical, damping and corrosion properties of Inconel 718 hard-faced stainless steel 304 using cold metal transfer

Cold Metal Transfer process is used to hard-face the Inconel 718 alloy onto the Stainless Steel 304 material. The optimized parameters from the Bead on Plate trials were determined as a wire feed rate of 7 m/min, deposition speed of 15 cm/min, welding current, and voltage of 175 A and 14.9 V, respectively. Hard-facing is carried out with the sinewave weaving technique along 30 % of overlapping beads. The analysis is focused on revealing the hard-faced specimens' microstructural, mechanical, and electrochemical corrosion properties. The hard-face layer exhibits grains of mixed modes, including columnar, cellular, and fine equiaxed grains. The increased heat transfer disintegrates grain formation and reduces secondary arm spacing development. SEM-Elemental mapping shows the reduction of Niobium (3.61 %) segregation and laves formation. The overlay layer has a maximum hardness of 343.1 HV0.5 over the base substrate with 204 HV0.5. The impact test reveals the hard-faced layer absorbs more energy (26.3 %) than the substrate. Dynamic Mechanical Analysis results indicate overlay layer enhancing damping properties. The electrochemical corrosion test findings suggest that the hard-faced layer's high corrosion potential (Ecorr = 8.533 mV) corresponds to a high corrosion resistance. Phase and intermetallic formations, distribution of elements, fractured and corrosive surface morphologies are analyzed using SEM, EDX, and elemental mapping results.

Nitriding of hardfaced layers as a method of improving wear resistance of hot forging tools

The article deals with novel hybrid layers combining hardfacing and nitriding to improve forging tool durability. It includes a study of the nitriding capabilities of hardfacings made of typical materials used to repair key groups of hot forging tools. Tests were conducted on samples and on tools in forging processes. Tests on samples included hardfacing, nitriding, microstructure, microhardness, XRF phase analysis and abrasive wear tests. Experimental tests on forging tools included operational tests and comprehensive wear analysis by scanning, macroscopic and microscopic observations by light and scanning microscopy, and analysis of wear mechanisms. Tests on the samples confirmed the positive effect of nitriding on performance properties at room and elevated temperatures. They revealed the reduced susceptibility to nitriding of some welds and the variable composition of nitrides present on the surface of the samples, which has a key effect on the observed wear mechanisms in the ball-on-disc test. Operational tests showed the effect of improved durability, which is greatest for the DO*15 (Fe–Cr–Mo–W) + nitriding layer which is due to the increased hardness of the weld itself and the increased susceptibility to nitriding.

Study into the process of defective railtrack arc-hardfacing

The paper focuses exclusively on the manual arc hardfaced layers of railtrack repairing. The study is conducted in two stages- structural analysis of layers and mechanical characteristic(hardness) study. Two types of technologies for defective areas rebuilding are developed. The first one is hardfacing without a buffer layer, and the second one is with a buffer layer. The process is carried out using electrodes particularly appropriate for this purpose, namely OK 83.28 and OK 67.45, and is designed to achieve the original hardness of the railtrack. All in all, the desired hardness value and magnitude can be achieved by hardfacing the defective areas without a buffer layer, and with the use of OK 63.28 electrodes.

Experimental investigations on Inconel 718 hard-faced layer deposited over SS304 using cold metal transfer

This study used the cold metal transfer (CMT) process to deposit Inconel 718 (IN718) as a hard-facing layer on the Base Substrate (BS) of 304 stainless steel (SS304). Different profiles like straight/stringer and sinewave weaving techniques are adopted to deposit the hard-faced layers. For the above profile, IN718 is deposited as a single-track and 30 % overlap to study the impact of heat input on the base substrate. Through the Bead on Plate (BoP) trials, optimal parameters of welding current (175 A), speed (15 cm/min), and wire feed rate (7 m/min) is identified. Sinewave beads (single track) explored a minimum dilution of 13.46 % compared to all the combinations. The sinewave distributed the heat uniformly compared to the straight/stringer profile. At the top surface, fine grains with an equiaxed structure are identified. Annealed twins are present at the base substrate, and elongated columnar grains near the interface are identified through EBSD. The sinewave with 30 % overlapped layers exhibited a maximum hardness of 274.4 HV0.5 at the Hard Face Zone (HFZ), whereas the base substrate hardness was 204 HV0.5. Further, the hard-faced samples achieve an ultimate strength of 750 Mpa through the tensile test. The micro-voids, dimples, and riverine structure observed from fractured surfaces witnessed the ductile fracture. The segregation of Niobium is scattered at the inter-dendritic region. The SEM-EDX results confirm the existence of Niobium, Nickel, and Molybdenum elements.

Effect of buttering on the wear behavior of the SMA welded hardfacing layer in a low-carbon steel

Abstract In this study, the effect of the buttering layer (18.5% Cr + 9% Ni) and the chemical composition of the hardfacing filler materials on the microstructure and wear behavior of the structural steel (S355JR) was investigated. The chromium-based hardfacing alloys deposited by shielded metal arc welding (SMAW) have also been investigated to establish the relationship between microstructures and wear properties. The microstructure of hardfacing deposits has been examined by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. A linear reciprocating abrasive wear test experiment was conducted on the hardfacing deposits using an Al2O3 ball under constant wear test conditions. The experimental results show that the microstructure of hardfacing deposits consists of martensitic matrix and complex (M7C3) carbides. In addition, the increased chromium concentration of filler materials leads to an increase in the volume fraction of the primary carbides in the matrix of hardfacing deposits. The buttering layer caused the formation of diluted hardfacing deposits. Also, it significantly reduced the hardness and wear rate of hardfacing deposits. Fe14-Fe14 hardfacing deposit has exhibited the best wear properties with a low coefficient of friction.

Effects of flux-cored arc welding technology on microstructure and wear resistance of Fe-Cr-C hardfacing alloy

This research presented the effects of flux-cored arc welding (FCAW) with and without preheating, gas-shielding and buffering conditions on the microstructure and wear resistance of Fe-Cr-C hardfacing alloy. The flux-cored wires based on austenitic nickel and Fe-Cr-C alloyed steel were used as buffer and hardfacing layers. The welding quality was inspected by visual test (VT) and penetrant test (PT). The structural characteristics were analyzed by optical microscope (OM), X-ray diffractometer (XRD), and scanning electron microscope with energy dispersive X-ray spectrometer (SEM-EDS). The results exhibited that the preheating, gas-shielding and buffering could improve the quality, dilution and weldability of the hardfacing weld. The structural phase of the hardfacing weld was found in the form of (Fe,Cr)7C3 mixed with martensite-austenite matrix (MA matrix). The buffering could combine the interphase of hardfacing to structural steel base resulting in the reduction of crack and carbide precipitation (Fe3C) at the fusion line from the effect of elemental dilution. The combination of buffer and hardfacing layers affected to crystallite size and fraction ratio of (Fe,Cr)7C3 to MA matrix increasing the elemental diffusions. According to the wear testing results (hardness, impact and abrasion), it was found that the preheating, gas-shielding and buffering FCAW provided an excellent wear resistance of Fe-Cr-C hardfacing alloy due to the present of (Fe,Cr)7C3 eutectic carbide in a high fraction of MA matrix resulting in good toughness-hardness balance properties. In addition, the suitable FCAW condition from the study could be applied for hardfacing of the tooth plate of crushing roller that was used in the biomass energy industry with better service life than traditional FCAW.

Investigation of the Microstructure and Corrosion Behaviors of Composite Hard-Faced Layers on Al5052 Using SiC and TiB2 in 3.5% NaCl and 0.5 M H2SO4 Solutions

Investigation of the Microstructure and Corrosion Behaviors of Composite Hard-Faced Layers on Al5052 Using SiC and TiB2 in 3.5% NaCl and 0.5 M H2SO4 Solutions