Dissimilar Metallic Materials Research Articles

Finite element analysis and experimental study on laser welding temperature field of dissimilar metal materials

Aiming at saving defects and cracks of dissimilar metal materials laser welding, the finite element analysis of temperature field and new welding process of stainless steel/Al, stainless steel/Cuwere developed in this work.Taking stainless steel/Al, stainless steel/Cu dissimilar materials laser welding for example, the physical model was established, and the finite element simulation of three-dimensional temperature field of laser welding was carried out based on Abaqus CAE. The results show that the simulation of temperature field provides reference for experimental process parameters, fiber laser welding is applicable to stainless steel/Cu, stainless steel/Al with lower laser welding defect.The process parameters were optimizedto achieve better welding quality and solve welding defects.The accurate prediction of temperature field distribution in dissimilar materials laser welding is great significance for practical process guidance.

Friction Stir Spot Welding of Aluminum and Copper: A Review.

Aluminum (Al) and copper (Cu) have been widely used in many industrial fields thanks to their good plasticity, high thermal conductivity and excellent electrical conductivity. An effective joining of dissimilar Al and Cu materials can make full use of the special characteristics of these two metals. Friction stir spot welding (FSSW), as an efficient solid-state welding method suitable for joining of dissimilar metal materials, has great prospects in future industrial applications. In this paper, the FSSW studies on Al-Cu dissimilar materials are reviewed. The research progress and current status of Al-Cu FSSW are reviewed with respect to tool features, macroscopic characteristics of welded joints, microstructures, defects in welds and mechanical properties of joints. In addition, some suggestions on further study are put forward in order to promote the development and progress of Al-Cu FSSW studies in several respects: material flow, thermal history, addition of intermediate layer, auxiliary methods and functionalization of Al-Cu FSSW joint.

Weldability of Similar and Different Metallic Materials

This Paper presents the study on the weldability of two similar and two different metallic materials. The weldability of the similar metallic materials considered in the study were aluminum alloy pipes of grade AA6063. As for the weldability of two different metallic materials were aluminum alloy of grade AA6061 to low carbon steel of grade A36, dupl stainless steel of grade 2205 to low carbon steel of grade A36 and grey cast iron of grade A48 class 35 to low carbon steel BS 449 of grade 250. The differing methods of welding or joining processes are discussed herein including those of stir welding and hot pressed diffusion bonding of the similar and dissimilar metallic materials respectively as mentioned above. The weldability of between the two materials are investigated including the physical appearance of the joints and the strength integrity of those so far achieved at this stage. The paper also presented the results on the weldability of the similar and different metallic materials, recommendation for further in-depth study in pursuit for improved technologies on the subject matters and highlight the prospects of metallic materials welding or bonding or joining to fulfill the demands for different applications.

Influence of Oxide Film on Surface Activated Bonding of Dissimilar Metallic Materials

Influence of Oxide Film on Surface Activated Bonding of Dissimilar Metallic Materials

Multilayer “Steel/Vanadium Alloy/Steel” Hybrid Material Obtained by High-Pressure Torsion at Different Temperatures

The severe plastic deformation (SPD) method for joining dissimilar metal materials to obtain a multilayer hybrid material having an ultrafine or nanoscale structure was proposed. A nanostructured multilayer “0.08C-18Cr-0.5Ti steel/V-10Ti-5Cr alloy/0.08C-18Cr-0.5Ti steel” hybrid material was obtained by high-pressure torsion (HPT) at different temperatures. The analysis of the structure of the hybrid material and its components was carried out by the methods of transmission and scanning electron microscopies. The distribution of chemical elements in the cross section of the hybrid material was studied by X-ray microanalysis. The microhardness was measured to estimate the hybrid material hardening after HPT. Tight joint zones between the layers of the hybrid material were formed during HPT. The fragmentation of the steel and vanadium alloy layers was observed, and the “mixing” of the layers occurred after HPT at 293 K and 473 K (20 °C and 200 °C). A smoother interface between the layers was observed after HPT at 673 K (400 °C). The significant hardening (2.0 to 3.5×) of each layer of the hybrid material was observed as a result of HPT.

Laser welding of dissimilar metallic materials with use of diffractive optical elements

A use of laser technology it is progressive in the welding of dissimilar materials. Pulsed laser welding of an aluminum alloy AK4 and a titanium alloy VT5-1 was performed. Processing conditions were determined, the realization of which during melting of materials in the heat-affected zone makes it possible to obtain a homogeneous structure without voids and shells, potentially producing sufficiently sound welded joints. To create the required power density distribution across the laser beam, it was found expedient to use diffractive optical elements. Aluminum and copper were welded by continuous laser beam. It is determined that laser action with its well-defined and precise localized heat input makes it possible to significantly reduce the growth of intermetallic compound layers.

Optimization of weld bonding process parameters of austenitic stainless steel 304L and low carbon steel sheet dissimilar joints

Weld bonding is a hybrid joining process used to produce weld joints between similar or dissimilar metallic materials. In this work, a systematic study has been undertaken to investigate the effect of the input process parameters on the weld joint quality of dissimilar materials i.e. austenitic stainless steel 304L and low carbon steel sheet, in terms of joint strength. Experiments were planned on the basis of response surface methodology technique with three control factor and their three levels of process parameters. Experimental results were used to develop a mathematical model to predict the tensile shear strength and peel strength of the weld joint. A mathematical model, correlating the process parameters and their interaction on responses, was also established. The developed model was validated with the confirmation test case experiment, and it has been observed that the developed model is capable to evaluate weld joint strength within the range of process parameters being used. Numerical optimization technique was applied to find out the optimal set of input parameters.

Hydrogen stress cracking in power generator M42 galvanized martensitic carbon steel screws

Screws are used to fasten parts of an assembly together, and can be used to join most classes of materials. The use of sufficient initial tension is very advantageous in reducing the fatigue effects when cyclic loads are present. In general, there is high applied stresses to preserve the joining, and in many practical applications the electrical contact of dissimilar metallic materials is unavoidable. On specific environmental condition, a potential difference produces electron flow between dissimilar materials, corroding the less corrosion-resistant metal. Thus, a better understanding of this joining process and environmental interactions are needed to predict failures in design, avoiding disasters and financial losses. An unexpected fracture in power generator M42 screws was investigated by failure analysis including visual, fractographic, microstructural, chemical and mechanical characterization. It was found that the fracture has no fatigue or plastic deformation signs, and the screws are free of microstructural or mechanical failures arising from raw material or manufacturing process. Intergranular fracture and grain boundary gaps were evidenced, due to this fact, localized fracture area and high-stress level in mounting condition, it was determined that failure cause was Hydrogen Stress Cracking (HSC). Hydrogen source was a galvanic couple between the screw material and cadmium coating. As recommendations, in acid medium presence, martensitic carbon steel screws should never be cathode in a galvanic couple, they must be replaced to obtain minimum levels of uniform corrosion and should not be painted.

144 異種金属微細接合角部の電子流集中による原子集積とマイクロ材料創製

144 異種金属微細接合角部の電子流集中による原子集積とマイクロ材料創製

Rate sensitivity of mixed mode interface toughness of dissimilar metallic materials: Studied at steady state

Crack propagation in metallic materials produces plastic dissipation when material in front for the crack tip enters the active plastic zone traveling with the tip, and later ends up being part of the residual plastic strain wake. Thus, the macroscopic work required to advance the crack is typically much larger than the work needed in the near tip fracture process. For rate sensitive materials, the amount of plastic dissipation typically depends on the rate at which the material is deformed. A dependency on the crack velocity should therefore be expected. The objective of this paper is to study the macroscopic toughness of crack advance along an interface joining two dissimilar rate dependent materials, characterized by an elastic-viscoplastic material model that approaches the response of a J 2-flow material in the rate independent limit. The emphasis here is on the rate sensitivity of the macroscopic fracture toughness under mixed Mode I/II loading. Moreover, special cases of joined similar rate dependent materials, as well as dissimilar materials where one substrate remains either elastic or approaches the rate independent limit is also included. The numerical analysis is carried out using the SSV model [Suo, Z., Shih, C., Varias, A., 1993. A theory for cleavage cracking in the presence of plastic flow. Acta Metall. Mater. 41, 1551–1557] embedded in a steady state finite element formulation, here assuming plane strain conditions and small-scale yielding. Results are presented for a wide range of material parameters, including noteworthy observations of a characteristic crack velocity at which the macroscopic toughness becomes independent of the material rate sensitivity. The potential of this phenomenon is elaborated on from a modeling point of view.

Electron beam welding of thin-walled structures made of dissimilar metallic materials

An engineering solutions system is considered to substantiate creation of a thin-walled structures industrial process from dissimilar materials, allowing for significant quality increase and for reducing materials consumption of the welded constructions, thanks to the joining efficient selection and optimum process, enabling required composition, structure, and properties of the welded joints.

Methods for surface preparation for brazing dissimilar metallic materials

Methods for surface preparation for brazing dissimilar metallic materials

Friction Stir Lap Welding of Magnesium Alloy and Zinc-Coated Steel

AZ31 Mg alloy and zinc-coated steel were lap welded using friction stir welding technology. The microstructures and mechanical properties of the joints were examined. The lap shear tensile test results showed that the welding speed had a significant effect on the failure loads of the joints at the rotation speed of 1500 rpm. The maximum failure loads of 3.4 kN, 65% of that of the zinc-coated steel base material, could be obtained when the welding speed was 150 mm/min. Microstructure analysis showed that the intervention of zinc coat promoted the formation of Mg-Zn low-melting-point eutectic structure at the interface. The joining mechanism and the role of Zn coat on friction stir lap welding of Mg alloy and zinc-coated steel were put forward. (doi:10.2320/matertrans.M2009022) Magnesium alloys, the lightest of the structural metals, with a density two-thirds that of aluminum alloy are a promising structural material in vehicle fabrication. Zinc- coated steel with excellent corrosion resistance and good durability is a promising structural material in vehicle applications. In order to achieve combined properties of magnesium alloys and zinc-coated steel, development of reliable joints between magnesium alloy and zinc-coated steel is necessary. As a solid state welding technology, friction stir welding (FSW) process 1) can be used to join Mg alloys 2-6) and steel 7-14) and gets high quality joints than fusion welding technology. Such good merits are also expected for joining dissimilar metal materials. Watanabe et al. 15) studied the weldability of FSW AZ31 magnesium alloy/SS400 steel, and reported that the rotation speed, the position of the pin axis had a significant effect on the strength and the microstructure of the joint. The maximum tensile strength of a butt joint reached about 70% of that of the magnesium base metal and the fracture path was along the joint interface. Liu et al. 16) studied the lap joining of the dissimilar alloys of AZ31B Mg alloy and 304 steel by a laser-GTA hybrid welding technique. A transitional zone formed at the interface of the Mg-Fe during laser-GTA hybrid welding and Mg diffused into the matrix of Fe in the form of oxides and reacted in the transitional zone. During tensile testing, the joints fractured at the interface between the Mg alloy and the steel. The metallic oxides produced at the Mg-Fe interface deteriorated the mechanical properties of the joints. Up to date, current studies only report the weldability of FSW or a laser-GTA hybrid welding of magnesium alloy/ steel and the preliminary results of mechanical properties and microstructure evolution of the joints. 15,16) Investiga- tions on FSW of magnesium alloy and zinc-coated steel have not yet been reported. The object of the present study is to examine microstructure evolution and mechanical properties in FSW magnesium alloy and zinc-coated steel. In this study, AZ31 magnesium alloy and low carbon zinc- coated steel are selected for friction stir lap welding. The magnesium alloy sheet is put on the zinc-coated steel sheet. The inserting depth of the tool, being strictly controlled, is less than the thickness of the magnesium alloy. That is, the probe tip of the tool does not reach the surface of the zinc- coated steel sheet during welding. The emphasis is to study the interface microstructure evolution and clarify the joining mechanism.

3020 微小接合幅を有する薄板異種金属の重ね合わせ固相接合

The solid-phase lap joining of layered thin metal materials is done by using the friction stir action. The proposed method can join the interface between the layered dissimilar metal materials with the minute joining width 1 mm or less. As the dissimilar materials, aluminum material and stainless steel are used. The rotating tool for friction-stir action is pressed down onto the upper thin aluminum plate, which is layered on the thin stainless steel. The generated friction heat and plasticity flow makes it possible to join the interface of layered dissimilar metals with the minute joining width. The temperature rises are measured at the bottom surface of the layered stainless steel under the conditions of the different keeping times and various indentation depths of the tool. It is shown that joining and non-joining conditions are deeply affected by the temperature distribution and the proposed solid-phase joining method enables the high coefficient joining.

ガルバニー電流によると思われた舌炎症例

A galvanic current may be caused in the oral cavity when two or more dissimilar metallic repair materials are present, and it is well known among dentists that severe pain, called “galvanic pain”, may result. We report two cases of glossitis thought to have been caused by oral galvanism. We measured the galvanic current in patients with glossitis and found significantly larger electric currents in the patients than in controls. We suspect that oral galvanism is the cause of glossitis when the conditions are as follows: 1) Anemia, medications, mechanical stimulation by dental repair, zinc deficiency, etc. have been ruled out; 2) Currents greater than five micro-amperes are demonstrated.

Ｓ４５Ｃ鋼同種摩擦圧接継手の統計的疲労特性について

Recently the application of the friction welded butt joint to mechanical structures has come into wider use. A further increase in demand for this sort of joint is anticipated because of its utility for some engineering purposes and the technical easiness of this welding method to make the butt joint of dissimilar metallic materials. However, there exist only a few papers concerned with the fatigue strength characteristics of this type of joint, for it has been recognized empirically that the fatigue strength of the friction interface exceeds that of the base material and thus no noticable problem on this type of joint exists from the view point of fatigue strength.In the preliminary study conducted by the authors on the friction welded butt joint specimens composed of 0.23%C carbon steel, however, it was revealed that the fatigue lives of these specimens showed a considerably wide scattering in comparison with those of the base material specimens.To clarify such statistical fatigue strength characteristics of the friction welded butt joint specimens, a series of experiments were planned and conducted on the base material specimens of 0.46%C carbon steel and the friction welded butt joint specimens at several stress levels in the overstress range.Statistical discussions on the results obtained were made by accepting the Weibull distribution as the original distribution for the fatigue life. It was revealed that there existed a distinct difference in S-N relation between the base material specimen and the friction welded butt joint specimen, when the distribution of fatigue life was taken into consideration.