Mechanical behavior of two-layer METAL laminate structures under low-speed impact loading was investigated experimentally and numerically. The experimental results were just used for validation of numerical results. Then numerical modeling was used to study the behavior of METAL laminates in details. The mechanical behavior of the METAL laminate structures under impact loading was found to be dependent on the material substance of the layers. The METAL layers were made of four common materials used in the industry. Results showed that the maximum amount of contact force and minimum amount of contact duration for the METAL laminate structures with similar METAL layers were obtained when the layers were made of steel. Whereas, the maximum amount of displacement and dissipated energy were achieved for the structure with lead layers. For the structures in which the first METAL layer was Al-6061T6, the maximum contact force obtained when the second METAL layer was made of steel; and the maximum displacement occurred when the second METAL layer was made of lead. It was found that the maximum mean amount of contact force belonged to the structures with first METAL layer of steel and the maximum mean amount of displacement belonged to the structures with the first METAL layer of lead. The finite element analysis results were in good agreement with the experimental results and also with the other researcher’s results.

Friction Stir Welding (FSW) is a solid state welding method. Now, for joining the variety of materials, especially DISSIMILAR METALs, has many applications. This method has no restrictions on the fusion welding. In addition to its many advantages, including the joining of METALs with different melting points. In this paper, a successfully joint between Al5050Aluminum alloys to AISI304 stainless steel was reported. Friction Stir Welding (FSW) process was used for joining these DISSIMILAR materials. In friction stir welding many parameters such as tool rotational speed, feedrate, offset and pin profile were effective on microstructure and mechanical properties of weld nugget by. This paper is focused on the effect of tool rotational speed, feedrate and offset on tensile strength and micro-hardness. In addition, effect of annealing operations was investigated on m crostructure and mechanical properties of the weld nugget. The elongation and tensile strength of the weld nugget were increased 100 and 9 percent respectively by the annealing process.

Phased Array Ultrasonic Testing (PAUT) is one of the most efficient and economic methods for inspecting weld joints. In some industrial applications, DISSIMILAR METAL Welds (DMW) is used for connecting the austenitic stainless steel pipes to the ferritic steel. Inhomogeneity and anisotropy of DMW causes ultrasonic waves to skew and attenuate. This issue can decrease the defects echo and reduce the probability of detecting them. Therefore, PAUT is used for inspection of DMW due to its ability to steering and focusing the ultrasonic waves. Simulation tools can help to understand how the ultrasonic waves are propagating in this kind of material to improve the inspection process. Conventional focusing technique is used for focusing waves in the homogenous and isotropic media. However, this technique cannot be used for focusing waves in DMW. In this paper, the conventional focusing technique developed for focusing ultrasonic waves in inhomogeneous and anisotropic media. Results of ultrasonic waves focused on defect in DMW media by the developed conventional focusing technique are compared and validated by adaptive focusing technique. Simulation results have been shown that developed conventional focusing technique has acceptable accuracy operation for focusing waves in inhomogeneous and anisotropic media such as DMW. In addition, the amplitudes of the defect echoes has increased about 235% compared to conventional ultrasonic testing.

In this research the interface structure of DISSIMILAR joint between AISI 4130 and AISI316L steels produced by GTAW process was evaluated. ERNiCr-3 was used as a filler METAL for this joint. After welding the microstructure of different areas including weld METALs, heat affected zones and interfaces were studied by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis. It was found that the weld METAL entirely has astenitic microstructure with relatively equiaxed grains and denderitic morphology. The results also showed that the grain growth in 4130 steel-weld METAL interface was unepitaxial due to the severe difference in chemical composition between the base and weld METALs. Microhardness measurements showed that the welded sample indicated the highest microhardness in the heat affected zone of 4130 steel because of the presence of tempered matensite and bainite in this area. In the weld zone a decrease in hardness value from AISI 4130 steel to AISI 316L can be seen. This reduction in microhardness can be due to the less amount of carbon in the weld area in vicinity of the AISI 316L base METAL.

Both Ti-6Al-4V and 316L stainless steels are widely used as engineering alloys in many modern industries, especially aerospace, gas turbine engines and heat exchangers due to high mechanical properties, high creep, fatigue, and corrosion resistance. Fusion welding of these alloys is not easily possible due to their incomplete solubility in each other. Brazing is one of the best choices for joining DISSIMILAR alloys. Infrared brazing is a novel process characterized with a high heating rate up to 500 °, C/min. Accordingly, it is expected that both erosion of the substrate and excessive growth of interMETALlic phases in the brazed joint are signifi, cantly decreased. This study is focused on the infrared brazing of Ti-6Al-4V and 316L stainless steel to investigate the influence of brazing parameters (brazing alloy, temperature and time) on microstructure and mechanical properties of base METALs with CBS 34 (Ag-based) braze filler foils. Brazing was performed in a home-made infrared furnace at temperatures of 750, 780, 800, 850 and 900 °, C for 3-5 min. Qualities of the brazed joints were evaluated by microstructure and phase constitution of the bonded joints with light optical microscope (LOM) and scanning electron microscope (SEM). Mechanical properties of the brazed joints were evaluated by hardness test. The optimum brazing parameters were at 850 °, C-5 min for CBS 34 filler foils.

In this research, the effect of different filler METALs on microstructure and mechanical properties of DISSIMILAR joint between AISI316 and AISI430 stainless steels was studied. For this purpose, GTAW process with ER308L, ER309L and ERNiCrMo4 filler METALs with diameter of 2. 4 mm were used. Microstructure and fracture surfaces of the welded samples were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and ferritoscopy. Also, the mechanical properties of the joint were evaluated by tension, impact and microhardness tests. The results show that the microstructure in the welded sample with ER308L filler METAL was austenitic with lathy and skeletal ferrite and Widmanstatten austenite. In the welded sample with ER309L filler METAL the microstructure was composed from austenite with skeletal ferrite and in the welded sample with ERNiCrMo4 filler METAL was fully austenitic. In tension test, all samples fractured from AISI430 base METAL in a ductile manner. ER309L filler METAL indicated low impact energy of about 49 J and ER308L and ERNiCrMo4 filler METALs indicated higher impact energy of about 120 and 73 J, respectively. The fracture of the weld METAL in the welded samples with ER308L and ERNiCrMo4 filler METALs was ductile and in the welded sample with ER309L filler METAL was more brittle. The results of microhardness test indicated that ER308L and ERNiCrMo4 filler METALs had higher microhardness as compared with ER309L filler METAL due to the presence of alloying elements, finer microstructure and higher grain boundaries.

This study was intended to investigate the synergistic effect of zirconium element on the active filler METAL, using a multi-component filler alloy. The bonding of alumina to copper was investigated using active filler METALs, namely Ag-Cu-Ti-Sn and Ag-Cu-Ti-Sn-%5. 1Zr, using the induction brazing method. Alumina/copper joining was done with active filler METALs of Ag-Cu-Ti-Sn and Ag-Cu-Ti-Sn-%5. 1Zr at temperatures of 840 and 880 °C, respectively, for 15 min under vacuum of 10-6 millibar. The microstructure of the joints were assessed using optical and scanning electron microscopes, equipped with energy dispersive spectroscopy and the mechanical properties of the joints were evaluated using the shear strength and the Vickers microhardness tests. Two phases of TiO and Cu3Ti3O were detected in the reaction layer area in alumina-copper joint with Ag-Cu-Ti-Sn filler METAL. Ag-Cu eutectic compounds were also found in the brazing zone. In alumina-copper joint with Ag-Cu-Ti-Sn-%5. 1Zr filler METAL, two phases of TiO and ZrO2 were observed in the reaction layer area, and two phases rich in copper and silver were observed in the brazing zone. The shear strength, obtained in brazing joint with Ag-Cu-Ti-Sn-%5. 1Zr filler, was 33% higher than that of in the brazing joint with Ag-Cu-Ti-Sn filler. The microhardness in the region of the reaction layer of the joint with filler METAL containing 5. 1 wt. % of zirconium and that without zirconium was measured as 248 and 146 Vickers, respectively.