Dissimilar Friction Welding Research Articles

A Comparative Analysis of Single and Multi-objective Process Parameter Optimization of Dissimilar Metal Friction Welds

A Comparative Analysis of Single and Multi-objective Process Parameter Optimization of Dissimilar Metal Friction Welds

Experimental Investigation of Material Flow and Welding defects in Friction Welding process of Cu-SS Dissimilar Materials

Abstract: A particular form of welding that makes use of the heat produced by friction is called friction welding. A pressure force contacts the surfaces of two materials that need to be connected; one is rotating while the other is at rest. In order for the heat produced by the continuous friction to continue rising, friction is applied continually to the second contact surface. In this study, dissimilar friction welding between grade 308 L stainless steel (SS) and copper (Cu) is investigated for a pipe joint design with a wall thickness of 1.50 mm and an outer diameter of 13 mm. The machine RPM, dwell duration, friction time, and friction force are the constant parameters that are used. The maximum ultimate tensile strength of 764 MPa, or almost 128% of the SS base material, was found in the SS to SS weld sample and 104 MPa, or nearly 80% of the Cu basis material, in the CU to CU weld sample. The most significant maximum tensile strength of 349 MPa was achieved by SS to Cu. In along with the study of the mechanical behavior and microstructure, the weld quality was evaluated using corrosion behavior analysis and leak proof testing.

Sound dissimilar linear friction welding of A7075-T6 Al and mild steel by simultaneous interfacial deformation using higher forging speed

Sound dissimilar welding of heat-treatable A7075-T6 aluminum and mild steel is extremely difficult due to the formation of interfacial cracks. The present study aims to attempt linear friction welding (LFW) of high-strength A7075-T6 Al alloy and mild steel to obtain sound joints with the highest strength ever by controlling the quality deteriorating phenomena that previous studies have faced. In this study, LFW joints were fabricated under two different applied pressures of 100 MPa and 300 MPa at a forging speed of 5 mm/s, along with various forging speeds ranging from 5 mm/s, 10 mm/s, to 20 mm/s under an applied pressure of 300 MPa, and the joint microstructure, mechanical properties and interface macrostructure were investigated. Furthermore, thermal dependence behaviors of both alloys were systematically investigated to optimize the processing parameters, especially applied pressure during LFW. At lower forging speeds of 5 mm/s and 10 mm/s, the weld defects and un-bonded regions were observed near the center of the weld accompanied by unevenness of butt surface due to the relatively thick intermetallic compound (IMC) formed in the interface which greatly influenced the joint strength. In contrast, at the higher forging speed of 20 mm/s, weld defects at the joint interface were effectively suppressed by promoting the simultaneous and uniform interfacial deformation of both alloys thanks to the extremely thin IMC during LFW. Consequently, a highly efficient joint with 100 % efficiency was successfully obtained at higher forging speed of 20 mm/s and despite the occurrence of softening towards A7075, the fabricated joint displayed a base metal fracture towards the steel side.

Finite element modelling of transient behaviours and microstructural evolution during dissimilar rotary friction welding of 316 austenitic stainless steel to A516 ferritic steel

Inertia friction welding (IFW) is a near-net-shape joining process that produces high-integrity welds. The transient nature of this joining process necessitates the availability of reliable computational models to predict the evolution of temperature and deformation throughout welding. In this study, a thermo-mechanical finite element (FE) model, based on an adaptive remeshing technique, is proposed to simulate dissimilar joining of A516 ferritic steel and 316L austenitic stainless steel (SS). The results of FE model were evaluated and verified via comparing the shape/size of the flash, upsetting load and angular velocity profile of a physical weld produced by IFW trials. A good agreement was achieved between the appearance of the weld/flash and those predicted by the FE model, thus verifying the predicted temperature and strain distributions. The microstructural features across different weld regimes were also examined to correlate the concomitant changes with the simulated temperature profile.

High-pressure linear friction welding of dissimilar AA5052-H34 and AA6061-T6 joint

Dissimilar linear friction welding (LFW) of AA5052/AA6061 was performed at different applied pressures. A dissimilar joint obtained at a high applied pressure of 200 MPa exhibited a tensile strength equivalent to that of the AA5052 base material, mainly because of the high density of low-angle grain boundaries (LAGB) per unit area at the weld regions. Meanwhile, the joints obtained at low applied pressures of 30 and 100 MPa softened at the weld regions because the LAGB density decreased because of the increased peak welding temperature. Therefore, the joints fractured in the weld regions, and the tensile strength of the joints decreased. Because dissimilar AA5052/AA6061 joints have metallurgical inhomogeneities and strength mismatches, plastic strain constraints near the weld interface of the soft material inevitably occur during tensile testing. Although the Vickers hardness at the weld interface on the AA5052 side had the lowest value, fracture was suppressed owing to the plastic strain constraint. At 100 and 200 MPa, the average grain diameters as a function of Z on the AA5052 side of the dissimilar AA5052/AA6061 joints matched the plot obtained from the similar AA5052 joint. At an applied pressure of 30 MPa, the average grain diameter was much larger than that of similar joints because the dissimilar joints underwent lower strain during LFW compared to similar joints, which resulted in the suppression of grain refinement during continuous dynamic recrystallization (CDRX).

Interfacial microstructure and mechanical properties of rotary inertia friction welded dissimilar 422 martensitic stainless steel to 4140 low alloy steel joints

In this work, dissimilar rotary inertia friction welds between 422 martensitic stainless steel and 4140 martensitic low-alloy steel were made to fabricate prototype heavy-duty diesel engine pistons. The influence of the inertia friction welding process and post weld heat treatment (PWHT) temperature on the interfacial microstructure evolutions and corresponding effects on mechanical properties of the 422/4140 welds were evaluated in detail. Carbon diffused from the 4140 side to the 422 side during PWHT at 650 °C for 1.5 h, causing the formation of a hard carbide-rich layer on the 422 side, and a softer but discontinuous C-depleted layer the 4140 side. PWHT at 700 °C for 1.5 h greatly accelerated C diffusion across the interface relative to 650 °C, resulting in a thicker hard carbide-rich layer and a relatively thick and continuous layer of coarse C-depleted grains (ferrite) on the 4140 side. In addition, the PWHT temperature greatly influenced the tensile properties and fracture behavior of the welds, with the 650 °C PWHT-ed samples failing predominately in a ductile manner in the 4140 heat affected zone during tensile testing. Conversely, the 700 °C PWHT specimens exhibited a strength reduction compared with the 650 °C PWHT specimens because of additional coarsening of the interfacial ferrite layer and softening of the base materials during PWHT, with brittle fracture between the hard and soft layers the predominate failure mechanism. Based on the findings, a reduced PWHT temperature and/or time, minimizing the hardness differential of the base metals, and pre-heating the 422 steel prior to welding are the potential pathways to achieve a more optimal balance between desirable tempering and stress relief of the weld microstructure and undesirable C migration across the weld interface, and to reduce the strength mismatch across the weld.

Dissimilar linear friction welding of Ni-based superalloys

Linear friction welding is a solid-state, near-net shape manufacturing method for metallic alloys which is characterised by complex deformation and metallurgical actions at the weld interface. However, a lack of understanding of the welding parameter interaction and subsequent welding mechanisms is hindering the joint integrity enhancement of dissimilar linear friction welding. In this study, we investigated the influence of various process parameters on macro/micro-formation, microstructural evolution, and properties to establish optimal welding conditions for the sound linear-friction-welded joint integrity of dissimilar superalloys, IN718, and the powder metallurgy FGH96. Increased oscillation frequency or decreased applied pressure promoted continuous dynamic recrystallisation and grain refinement, although discontinuous dynamic recrystallisation remained dominant. Enhanced dissolution of the strengthening phases (γ′ phase on the FGH96 side and δ phase on the IN718 side) was observed from the thermomechanically affected zone to the interface. The subsequent correlation between the microstructure and mechanical properties indicated that solid–solution strengthening was the dominant mechanism for enhancing interfacial bonding, which was promoted by mutual material deformation on both sides. Accordingly, to achieve synergistic plastic deformation in dissimilar linear friction welding, an optimisation strategy of welding parameter combination was proposed and validated by investigating hot compressive dissimilar Ni-based superalloys. The results of simulations of sub-size workpieces showed that using linear friction welding to manufacture bimetallic bladed disks, from conception to completion, was feasible. The paper offers an integrated solution for the full-scale manufacturing of an IN718/FGH96 blisk using linear friction welding based on microstructure–property interactions and relevant simulations, which can ideally serve as the basis for future bimetallic bladed disk manufacturing.

Influence of Microstructure and Mechanical Properties of Dissimilar Rotary Friction Welded Inconel to Stainless Steel Joints.

The present study aims to evaluate the microstructure, grain size, and mechanical properties of the dissimilar AISI 316L/Inconel 718 (IN 718) rotary friction welded joints under both the as-welded and post-weld heat treatment (PWHT) conditions. Because of reduced flow strength at elevated temperatures, the AISI 316L and IN 718 dissimilar weldments exhibited more flash formation on the AISI 316L side. At higher rotating speeds during friction welding, an intermixing zone was created at the weld joint interface due to the material softening and squeezing. The dissimilar welds exhibited distinctive regions, including the fully deformed zone (FDZ), heat-affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and the base metal (BM), located on either side of the weld interface. The dissimilar friction welds, AISI 316L/IN 718 ST and AISI 316L/IN 718 STA, exhibited yield strength (YS) of 634 ± 9 MPa and 602 ± 3 MPa, ultimate tensile strength (UTS) of 728 ± 7 MPa and 697± 2 MPa, and % elongation (% El) of 14 ± 1.5 and 17 ± 0.9, respectively. Among the welded samples, PWHT samples exhibited high strength (YS = 730 ± 2 MPa, UTS = 828 ± 5 MPa, % El = 9 ± 1.2), and this may be attributed to the formation of precipitates. Dissimilar PWHT friction weld samples resulted in the highest hardness among all the conditions in the FDZ due to the formation of precipitates. On the AISI 316L side, prolonged exposure to high temperatures during PWHT resulted in grain growth and decreased hardness. During the tensile test at ambient temperature, both the as-welded and PWHT friction weld joints failed in the HAZ regions of the AISI 316L side.

Effect of Heat Treatment on the Microstructure and Mechanical Properties of Rotary Friction Welded Dissimilar IN718 to SS304L Alloys

The present study investigated the effect of heat treatment (pre- and post-weld) on the microstructure and mechanical properties of an SS304L/IN718 dissimilar rotary friction welded alloy. Optical and scanning electron micrographs of the dissimilar rotary friction welded SS304L/IN718 joints in solution-treated (ST), solution-treated and aged (STA), and post-weld heat treatment (PWHT) conditions revealed defect-free welds. Furthermore, various zones were observed across the weld region, namely the fully deformed zone (FDZ), thermomechanical affected zone (TMAZ), heat affected zone (HAZ), and base material (BM). Among the SS304L/IN718 dissimilar friction welds with different heat treatment conditions (prior ST and STA, PWHT), the PWHTed dissimilar welds exhibited excellent mechanical properties, which could be attributed to the formation of the strengthening precipitates γ′ and γ″ during double aging in PWHT. In contrast, the mechanical properties were found to be the poorest in the STA condition, possibly due to the dissolution of the strengthening precipitates γ′ and γ″ during friction welding. It was observed that the SS304L/IN718 dissimilar friction welds in the ST and STA conditions failed in the HAZ of the SS304L side, away from the weld interface, indicating that the weld region was stronger than the weakest base metal (SS304L) in the various joints.

Microstructural and Mechanical Properties of AZ31B to AA6061 Dissimilar Joints Fabricated by Refill Friction Stir Spot Welding

Dissimilar friction stir spot welds (FSSW) between the magnesium and aluminum alloys are joined, using a novel approach called refill friction stir spot welding. The present work aims to evaluate the macrostructural and mechanical properties of refill friction stir spot welded AZ31B and AA 6061-T6 alloys in two combinations, i.e., identical Mg-to-Mg and dissimilar Mg-to-Al joints, and the results are compared with the results obtained in conventional friction stir spot welding. The hardness profiles of the similar welds had the appearance of a W-shape, and the Thermo mechanically affected zone and heat-affected zone of both methods had lower hardness values than the rest of the weld. Along with the interface between the aluminum and magnesium sheets, a thin intermetallic compound layer of Al12Mg17 has been identified, which has led to an increase in hardness. The static shear strength of both similar and dissimilar refill spot friction welds was much greater than that of traditional spot friction welds. In both similar and dissimilar spot friction welds, two distinct failure scenarios are discovered.

Dissimilar friction welding of NiTi shape memory alloy and steel reinforcing bars for seismic performance

Integration of NiTi superelastic bars with steel reinforcing bars is a promising path for increasing the seismic performance of reinforced concrete structures. Welding of NiTi alloy to steel is however not straightforward with standard welding techniques. Friction welding is investigated for performing this dissimilar junction using both regular friction (forced controlled) and milling (position-controlled) machines. When adequate shortenings and forging forces are selected, the welds can withstand the tensile strength of the steel rebars. Failure actually occurs in the heat-affected zone of the steel bars. The intermetallic (IM) layer at the welded interface should be kept thin and cracks should be limited in the steel layer next to the interface in order to avoid early brittle interfacial cracking.

The Influence of Friction Time on the Joint Interface and Mechanical Properties in Dissimilar Friction Welds

The welding of dissimilar materials is one of the challenging issues in thefabrication industry to obtain required quality welds using fusion weldingmethods. However, some processes recently improved interface bondingwith low joint strength. Unfortunately, the major intermetallic compoundscould not alleviate from the joint interface. Alternatively, solid-statewelding methods revealed fewer intermetallics at the joint interface fordissimilar material welds. Among them, friction welding was chosen to joinincompatible materials with the necessary properties successfully. Frictiontime is a critical parameter for obtaining strong welds through frictionwelding, apart from friction pressure, forging pressure, forging time, androtational speed. Variability of friction time can change the strength offriction by changing mechanical properties such as tensile strength. Thischange of tensile strength is typically influenced by the intermixing region,dependent on friction time. In this experiment, carbon steel and stainlesssteel have been friction welded to test the impact of friction time on thejoint interface where the substrate’s faying surface meets. This interfaceconsists of the intermixing region of the two materials on which the frictionwelding is performed. The results showed an interesting variation in tensilestrength, with varying friction time. The width of the intermixing zoneincreased gradually with friction time until and decreased with the furtherincreasing. The strength of the welds obtained was the highest of 730 MPaat a friction time of 4 s and fell as friction time’s increased value after 4 s.

Dissimilar linear friction welding of selective laser melted Inconel 718 to forged Ni-based superalloy AD730™: Evolution of strengthening phases

The continuous growth in the manufacture of aerospace components such as blisks has led to an increase in the application of different hybrid materials fabricating methods, and thus the requirements for joining and strengthening of dissimilar welds. According to this goal, selective laser melted (SLM) Inconel 718 was joined with forged AD730™ Nickel-based superalloy through linear friction welding (LFW) in this study. Microstructure variation, specifically with respect to secondary phases precipitation was investigated. The microhardness and strengthening mechanisms of the weldment were also studied. The precipitation (volume fraction and size of particles) at different regions of both sides of the weld line was characterized. Close to the weld line, the dissolution of γ'/γ" and Laves phases and grain refinement occurred which reveals the effects of both compression strain and high temperature on recrystallization and high degree of elemental diffusion in the weld zone (WZ). It is shown that the size, volume fraction, and shape of secondary phases increased and changed (from spherical to long-striped for Laves particles) as we went from the WZ toward the base metal. However, the measured microhardness indicated that the strength of AD730™ alloy depends significantly on the grain size, while strength in SLM Inconel 718 was dominated by shape (or size) and the presence of secondary phases (γ'/γ" and Laves).

Dissimilar Rotary Friction Welding of Inconel 718 to F22 Using Inconel 625 Interlayer

Dissimilar metal joining has always been a challenging task because of the metallurgical incompatibility and difference in melting points of alloys being joined. Diffusion and mixing of alloying elements from dissimilar base metals at the weld often cause unwanted metallurgical changes resulting in unsuccessful welds or underperformance of the weldment. Solid-state dissimilar friction welds of Inconel 718 and F22 were prepared in this study with an Inconel 625 interlayer to address the carbon enrichment of Inconel 718 during the welding. Defect-free rotary friction welds were produced in this study. Microstructural and mechanical properties investigation of the weldments and base metals was carried out, and results were analysed. Intermixing zone was observed at the weld interface due to the softening of the metal at the interface and rotatory motion during the welding. The high temperatures and the plastic deformation of the intermixing zone and thermo-mechanically affected zone (TMAZ) resulted in the grain refinement of the weld region. The highest hardness was observed at the Inconel 718/F22 weld interface due to the plastic strain and the carbon diffusion. The tensile specimens failed in the F22 base metal for the weld prepared with and without the Inconel 625 interlayer. Inconel 718/F22 welds exhibited lower toughness values compared to the Inconel 718/F22 welds prepared with Inconel 625 interlayer.

Friction welding of dissimilar joints copper-stainless steel pipe consist of 0.06 wall thickness to pipe diameter ratio

This paper examines dissimilar friction welding between electrolytic tough pitch copper (ETP-Cu) and stainless steel (SS) of grade 304 L for pipe joint configuration, having 0.06 wall thickness to pipe diameter ratio. The welding is performed using the continuous drive friction welding method. The welded joint is evaluated by visual inspection, leak-proof ability by helium leak detection testing, microstructure features by optical and scanning electron microscopy, energy dispersive x-ray spectroscope, x-ray diffraction patterns, tensile testing, and hardness measurements. The continuity of welding is evaluated by peripheral inspection and testing on four different locations of pipe welded joint. The results revealed that sound joints between dissimilar materials of Cu-SS are established with evidence of resistance to leak at room temperature and after cryogenic shock test. The Cu-SS pipe joint received excellent strength of 242.48 N/mm2, which is nearly 80% of ETP-Cu base material. The microstructure changes are distinctly observed at the Cu side, whereas no significant microstructure changes are observed at the SS side. The microstructure features are consisting of full dynamic recrystallization zone and partial dynamic recrystallization zone that are identified at the Cu side. However, no adverse effect of microstructure on tensile strength and hardness is observed. The weld continuity in the periphery of pipe configuration is observed at four different locations. A continuous reaction layer at four investigated locations is identified, with the presence of Cu and Fe elements at the joint interface.

Post-Weld Heat Treatment of Additively Manufactured Inconel 718 Welded to Forged Ni-Based Superalloy AD730 by Linear Friction Welding

A new post-weld heat treatment (PWHT) cycle was designed for novel dissimilar linear friction welding (LFW) of selective laser melted (SLM) Inconel 718 (IN718) to AD730 forged nickel-based superalloy. The microstructure and hardness of the joints after the PWHT are investigated and compared with those of as-linear friction welded samples. The precipitation of γ′ + γ″ is determined as the main mechanism to increase the mechanical properties of SLM IN718 alloy. These particles coarsened during heat treatment at 1253 K and double aging. The results show that the thermomechanical history of linear friction welded joints can affect the microstructure of IN718 alloy such as the morphology of δ phase after solution treatment (ST) from the platelike in the weld zone (WZ) to the needlelike in the base material (BM). It was found that in AD730, nanometric size γ′ particles reprecipitated close to the weld line during rapid cooling after welding. The presence of ultrafine γ′ particles and coarsening of the remaining particles in the microstructure of the alloy, during PWHT, can enhance the strength and hardness. The developed PWHT resulted in uniform hardness across the new dissimilar joint.

Static and Fatigue Properties of Rotary Friction Welded Dissimilar AA7075/AA5083 Aluminium Alloy Joints at Various Rotational Speeds

In the present study, dissimilar rotary friction welding of AA7075/AA5083 aluminium alloy rods having diameter of 15 mm was conducted at various rotational speeds in the range of 370 to 2500 rpm. The aim of this research is to gain the best weld mechanical properties in particular weld tensile strength and fatigue performance. Several experiments were carried out including macro and microstructural examinations, microhardness measurements, tensile tests and fatigue tests combined with residual stress measurements. Results show that at higher rotational speeds, typically 540 rpm or above, the dissimilar AA7075/AA5083 rotary friction weld joints reveal static fracture in the AA5083 base metal side indicating the joint efficiency is more than 100%. It seems that the best weld joint is achieved at the rotational speed of 1200 rpm in which the friction heat is sufficient to form metallurgical bonding without causing excessive flash and burn-off shortening. In such a condition, the fatigue strength of the weld joint is slightly higher than its AA5083 base metal but it is lower compared to another AA7075 base metal. It is confirmed that the crack origin is observed at the interface followed by fatigue crack growth towards AA5083 side and the growth of crack seems to be controlled by microstructure and residual stress.

Continuous drive dissimilar friction welding of wrought aluminium AA6063-T6 and austenitic stainless steel AISI304L with different welding methods and welding trials

Continuous drive dissimilar friction welding of wrought aluminium AA6063-T6 and austenitic stainless steel AISI304L with different welding methods and welding trials

A new method of dissimilar friction welding of titanium to stainless steel

Friction welding is one of the method to join two or more metals, similar or dissimilar, to accomplish a certain fabrication. Two methods of joining prevail, one by the fusion state and the other by the solid-state. The selection of the joining method depends upon the materials used and the required performance of the joint. Friction welding is the solid-state welding process preferable for joining similar and dissimilar metals. Ti Grade 2 and stainless steel 304L of different compositions are used in this welding by the copper interlayer methodology. This material composition of welding has been very challenging of late. Friction welding components are very popular in automobile components, like ball link joint, turbocharger shafts, clutch hub, and axles housing. In the nuclear industry, dissimilar pipe joints and transition joints are used for nuclear reactors. This article describes friction welding of titanium and stainless steel with copper as intermediate layer.

Continuous drive dissimilar friction welding of wrought aluminium AA6063-T6 and austenitic stainless steel AISI304L with different welding methods and welding trials

Continuous drive dissimilar friction welding of wrought aluminium AA6063-T6 and austenitic stainless steel AISI304L with different welding methods and welding trials