Welding Of Dissimilar Materials Research Articles

Imaging Diffraction Using Maxim at G3/Hasylab - Spatial Resolved Strain Measurements on Linear Friction Welded Dissimilar Materials (AA7020-T6/Ti6AlV

Strain induced by friction welding of dissimilar materials was determined by an imaging diffraction technique using the Material X-ray diffraction Imaging (MAXIM) detector at HASYLAB G3. Applying the sin2Ψ method in ω mode, a stress profile perpendicular to the weld joint was derived. Results are discussed and compared with measurements of the same specimen made at the neutron source of the GKSS Research Centre.

Suppression of intermetallic reaction layer formation by controlling heat flow in dissimilar joining of steel and aluminum alloy

In order to suppress the formation of intermetallic reaction layer during laser welding of steel and aluminum alloy dissimilar materials, effect of backing block (heat sink) was investigated. FEM analysis as well as welding experiments with various backing blocks for controlling heat flow were performed. It was found that thickness of intermetallic reaction layer was reduced by increasing welding speed and by applying a backing block with higher thermal conductivity. FEM analysis also showed that when increasing welding speed or applying a backing block with higher thermal conductivity, molten time of aluminum alloy became shorter and predicted thickness of intermetallic reaction layer became thinner. It could be concluded that the thickness of intermetallic reaction layer could be suppressed by using a backing block (as a heat sink) for controlling heat flow in welding region. The joining strength was strongly dependent on the thickness of intermetallic reaction layer. Therefore the backing block was significantly effective for controlling heat flow and consequently for attaining good joining strength.

Effects of Laser Welding Conditions on Toughness of Dissimilar Welded Components

Welding dissimilar materials become inevitable in engineering industries. There are many issues/problems associated with the welding of dissimilar materials, related to the welding process and its parameters. The current work investigates the effect of laser welding conditions on the toughness of dissimilar welded components. In this study, CO2 laser welding has been successfully applied for joining 316 stainless steel with low carbon steel (F/A). Design of experiment techniques has been used for different effective welding parameters (laser power, welding speed, and focus position) to optimize the dissimilar F/A joints in terms of its mechanical properties. Taguchi approach was applied to optimize the welding parameters. Three factors with five levels each (L-25) were employed in these models. Impact strength was measured at room temperature by using the universal pendulum impact tester. The results were compared with the impact strength of the base material. The results were analysed using ANOVA and S/N ratio for optimal parameters combination. It is evident that Taguchi approach has decreased the number of experiments without negative effects on the result.

Microstructure and hardness of friction stir welded 7075 aluminium alloy joints

Friction stir welding (FSW) is a process which induces a reduction in flow stress owing to friction heat generated by pressing a protruded object into a solid material and rotating it at high speed. It induces part of the material to have plastic flow owing to friction force in order to join materials together.1 The FSW method was developed for the welding of aluminium alloy plates which have an extremely large number of restrictions when using fusion welding processes. However, the range of its employable usages has been expanding rapidly by including, as its applicable materials and processes, alloys with Cu,2 Ti,3 Mg4 and Fe5 as well as dissimilar material welding of these materials.

Joining of dissimilar materials with friction stir welding

The welding and joining of dissimilar metals which have very different properties, such as aluminium and carbon steel, is considered to be a subject for research and development in the welding/joining sector continuing into the 21st century. There are also huge requirements and expectations for this sector.1 Due to the aforementioned, the research and development of welding and joining of dissimilar materials have been carried out over many years; for instance, eutectic bonding of copper pipe and aluminium pipe was developed 30 years ago and this process is still applied for the heat pipes of refrigerators. Recently it has even progressed for applications in joining of wide plate materials of aluminium alloy and stainless steel by means of the vacuum rolling process2 and also for weldments of aluminium alloy and carbon steel joined by means of friction welding and employed as automobile components.3 However, there are problems from aspects of cost and restrictions concerning the configurations for which joining is feasible using conventional welding and joining processes and these techniques have not yet reached the stage where they can be applied in a number of industrial sectors. Accordingly, an extensive programme of research and development has been deployed in recent years using fusion welding processes, such as electron beam and laser welding and brazing, diffusion bonding and also friction stir welding (FSW).4

Characterization of Friction Welding for IN713LC and AISI 4140 Steel

Friction welding of dissimilar materials, Ni-base superalloy IN713LC and oil-quench plus tempered AISI 4140 steel, was investigated. Friction welding was carried out with various process variables such as friction pressure and time. The quality of welded joints was tested by applying bending stresses in an appropriate jig. Microstructures of the heat-affected zone (HAZ) were investigated along with micro-hardness tests over the friction weld joints. DEFORM-2D FE code was used to simulate the effect of welding variables in friction welding process on the distributions of the state variables such as strain, strain rate and temperature. The formation of the metal burr during the friction welding process was successfully simulated, and the temperature distribution in the heat-affected zone indicated a good agreement with the variation of the microstructures in the HAZ.

Friction Stir Welding – Recent Developments in Tool and Process Technologies

Improved weld integrity, reduced upper‐plate thinning, and higher welding speeds are some striking results of progress recently made in the field of friction‐stir welding through improvements of tools and processes. One technique, labelled Re‐Stir™, in particular, appears promising since it generates essentially symmetrical welds (see Figure for a cross‐section of the notch) and is potentially suitable for welding of dissimilar materials.

Laser penetration spike welding: A microlaser welding technique enabling novel product designs and constructions

A novel method for laser penetration microspot welding of sheet metal is presented. With this so called “laser spike-welding,” large gap tolerances are allowed. Depending on the ratio of laser spot radius to top plate thickness, gaps of 100% of the top layer thickness and more can be bridged. With conventional keyhole penetration welding this is only 20%–40% at most. So, with spike welding the gap between the metal plates can be increased by a factor of 2.5–5. In this way a powerful and attractive welding technique for joining of thin metal plates is available. The laser spike weld method can handle larger production tolerances and will enable novel and cheap product designs and welding of dissimilar materials.

Friction welding of similar and dissimilar materials: PMMA and PVC

AbstractThe effects of spin friction pressure and time on the friction welding between parts of the same material and different materials are discussed. The heat‐affected zone is divided into three regions: the plasticized region (Zpl), the partly plasticized region (Zpd), and the undeformed region (Zud). The tensile fracture morphology has three sections: the non‐plasticized central section (Fud), the plasticized peripheral section (Fpl), and the partly plasticized section between Fud and Fpl (Fpd). Friction pressure (spinning timing): 0.784 Mpa (6 seconds), 0.981 MPa (8 seconds and 10 seconds) in PMMA‐PMMA welding, 0.588 Mpa (10 seconds) in PVC‐PVC welding, and 15.7 MPa (15 seconds) in PMMA‐PVC welding attains better bonding strength, because these parts have larger Fpd and Fpl regions, which have no Fud in the central part.

Investigation into properties of laser welded similar and dissimilar steel joints

Laser beam welding is currently used in the welding of steels, aluminium alloys, thin sheets, and dissimilar materials. This high power density welding process has unique advantages of cost effectiveness, deep penetration, narrow bead and heat affected zone (HAZ) widths, and low distortion compared to other conventional welding processes. However, the metallurgical and mechanical properties of laser welds and the response of conventional materials to this new process are not yet fully established. The welding process may lead to drastic changes in the microstructure with accompanying effects on the mechanical properties and, hence, on the performance of the joint. The thermal cycles associated with laser beam welding are generally much faster than those involved in the conventional arc welding processes. This leads to the formation of a rather small weld zone that exhibits locally a high hardness in the case of C–Mn structural steels owing to the formation of martensite. It is currently difficult to determine the tensile properties (full stress–strain curves) of the laser welded joint area owing to the small size(∼V 2·3 mm) of the fusion zone. Complete information on the tensile and fracture toughness properties of the fusion zone is essential for prequalification and complete understanding of the joint performance in service, as well as for conducting a defect assessment procedure on such welded joints. Therefore, an experimental investigation into the mechanical properties of laser welded joints was carried out to establish a testing procedure using fiat micro tensile specimens (0·5 mm in thickness, 2 mm in width) for determination of the tensile properties of the weld metal and H AZ of the laser beam welds. Three similar joints, namely St 37–St 37, St 52–St 52, and austenitic–austenitic, and two dissimilar ferritic–austenitic joints were produced by CO2 laser, using 6 mm thickness plates. The mechanical properties have been examined by microhardness survey and testing of conventional transverse tensile, round tensile, and fiat microtensile specimens. The results for the micro tensile specimens were compared with those for standard round tensile specimens and this clearly showed the suitability of the microtensile specimen technique for such joints.

Real rotational contact plane in friction welding of different diameter materials and dissimilar materials: Fundamental study of friction welding

Summary The purpose of this paper is to clarify the mechanism of joint formation as part of a fundamental research programme centred on friction welding. The paper shows that, when combinations of different diameter materials and dissimilar materials are being friction-welded, the phenomenon of rotational plane transfer arises. As a result of this phenomenon, transfer of the rotational plane is found to occur in the central zone of the rotational plane, as demonstrated by observations of plastic flow using a tracer, and the friction welding metal transfers from the filler rod to the plate through the rotational plane. The centre of this rotational plane is defined as the real rotational contact plane in much the same way as in friction surfacing. The area of the real rotational contact plane decreases with an increasing rotational speed and friction pressure, and its diameter is shown to be determined by the friction upset distance (a) and mass of transferred metal (w). The paper further shows that the mechanism of real rotational contact plane decrease can be explained by the critical circumferential speed position of transfer from continuous shear deformation to plastic flow and that a number of phenomena in friction welding associated with an increase in the rotational speed and friction pressure can be explained by the decrease in the area of the real rotational contact plane

異径材及び異種材の摩擦圧接における真の回転接触面について 摩擦圧接の基礎研究

The travelling phenomena of the rotational plane arise in friction welding of different diameter materials and dissimilar materials, and friction surfacing is carried out by the phenomena. It has been revealed that in friction surfacing the real rotational contact plane exists at the central part of the rotational plane, the surfaced metal apparently transferrs from a filler rod to a plate through the real rotational contact plane owing to the travelling phenomena of the rotational plane, the area of this plane decreases with increasing rotational speeds and friction pressures, and the diameter of this plane {dc=2*√W/(πρa)} is calculated by a mass the surfaced metal (W) and a friction upset distance (a).This study also revealed that the friction welding of different diameter materials and dissimilar materials had the same phenomena of friction surfacing concerning the real rotational contact plane and a consideration for the decreasing mechanism of this real plane was described.