Investigation on the microstructure and mechanical properties of Ti6Al4V titanium alloy electron beam welding joint

Electron beam welding (EBW) is a fusion joining process particularly suitable for welding titanium plates. In the present work, 2.5 mm thickness Ti6Al4V titanium alloy plates were butt-welded together with backing plates by EBW. The detailed procedures of experiments were used to investigate the microstructure and mechanical properties of welded joints. The optimum welding speed was determined by microstructure examinations, microhardness tests, X-Ray diffraction tests, shear punch tests (SPT) and stress simulation calculations. The results showed that all microstructure of welded metal (WM) was martensite phase under the different welding speeds. In the heat-affected zone (HAZ), the martensite phase gradually evolved to be small and equiaxed. It can be seen that the microstructure of each region in welded joints did not change significantly. When the welding speed is between 8 mm/s and 14 mm/s, it can be seen from the macroscopic appearance of the joints that there was no utterly fused penetration between the butt plate and substrate. Finite element simulation was carried out for the no-penetration depth under different welding conditions, and it was found that the stress suffered by the small no-penetration depth was the smallest. Using different welding parameters shows that the engineering stress in WM was higher than other areas, and BM was the lowest. As welding speed increases from 8 mm/s to 14 mm/s, the variation of microhardness distribution was not evident.

The influence of friction stir welding tool shape on quality of AZ31 Magnesium welding product

Magnesium is one type of material that can be used as a base metal in welding. Magnesium has superior properties, including low density, good ductility, medium strength and excellent corrosion resistance. Because of its properties, the metal is widely used, ranging from household goods to aircraft components. These base metals are categorised as mild when viewed from the specific gravity of magnesium (1.74 g/cm3 and 1.83 g/cm3). Welding is the process of merging two or more base metals which are merged at the contact surface with or without additives or fillers. Welding is divided into two main categories, Liquid and Solid-State Welding. Friction Stir Welding (FSW) is an example of Solid-State Welding (Non-Fusion Welding). FSW is a friction welding process that twists the tool by utilising heat energy and pressing without additives or fillers until the base metal is in a phase change. The welding process in this study used the cone and spiral shape with a tool rotation at 2000 rpm and a welding speed of 16 mm/min. The tests carried out are tensile and hardness testing. This study found that the tool shape, tool rotation, and welding speed significantly affect the mechanical properties of the welded AZ31 magnesium. The spiral shape will make the welding area wider. Although the cone shape will have a small area, the weld will look perfect with good tensile strength, while the hardness values for the two tool shapes are almost the same, but the cone shape is better.

Microstructure and mechanical properties of dissimilar friction stir welds of AA2014 and AA7075

This work investigates the effect of process parameters on microstructure, mechanical properties, and fracture behavior of friction stir welded high-strength aluminum alloys AA2014-T6 and AA7075-T6. Optical micrograph, tensile property, and hardness profile of each weld were determined for analysis, and the tensile fracture surfaces were studied by scanning electron microscope. Welds microstructure were heterogeneous and displayed structures comprising of both base metals and the onion rings were seen in all welds except for the lowest heat input weld. Grains in the weld nugget zone were more refined on the retreating side than the other side. Asymmetric hardness profile had a distinct softened zone on each side whose location and softening extent varied with the processing parameters. Welding speed had a more significant effect on tensile strength than rotary speed and, drastically decreased the same. Faster welding speed formed microscopic defects and changed the appearance of fractured surfaces from flat to zigzag. The welds underwent ductile and mixed-mode tensile failure on the advancing side. Attainment of optimum combination of process parameters is imperative to yield defect-free stronger dissimilar welds

Forecasting process parameters on weld nugget hardness of filler added friction stir welded dissimilar aluminium alloys 5052 And 6082 joints

This article deals with the optimization of friction stir welding process parameters with filler ratios on dissimilar Aluminium alloy groups. For this purpose, 6 series Aluminium alloy 6082 and 5 series Aluminium alloy 5052 were taken. Microhardness property was conducted under various rotational speeds, welding speed, plunge depth, Center distance between the holes and filler mixing ratio. The Central Composite Design (CCD), the most commonly used Response Surface Methodology (RSM), is considered to develop the prediction equation. A validation analysis is carried out, and the results were compared with the relative impact of input parameters on weld nugget microhardness. It is observed that the increase in welding speed with plunge depth and filler ratio result in the increase of weld nugget microhardness up to a maximum value. The maximum weld nugget hardness of fabricated joint was obtained with the welding process parameters combination of 1000 rpm rotational speed, 125 mm/min welding speed, 0.15 mm plunge depth, 2 mm centre distance between the holes, and filler ratio of 95% Mg and 5% Cr.

Effect of process parameters on interfacial temperature and shear strength of ultrasonic additive manufacturing of carbon steel 4130

Ultrasonic additive manufacturing (UAM) is a solid state manufacturing process capable of producing near-net-shape metal parts. Recent studies have shown the promise of UAM welding of high strength steels. However, the effect of weld parameters on the weld quality of UAM steel is unclear. A design of experiments study based on a Taguchi L16 design array was conducted to investigate the influence of parameters including baseplate temperature, amplitude, welding speed, and normal force on the interfacial temperature and shear strength of UAM welding of carbon steel 4130. Analysis of variance (ANOVA) and main effects analyses were performed to determine optimal weld parameters within the process window. A Pearson correlation test was conducted to find the relationship between interfacial temperature and shear strength. These analyses indicate that the highest shear strength of 392.8 MPa can be achieved by using a baseplate temperature of 400°F (204.4°C), amplitude of 31.5 μm, welding speed of 40 in/min (16.93 mm/s), and normal force of 6000 N. The Pearson correlation coefficient is calculated as 0.227, which indicates a weak positive correlation between interfacial temperature and shear strength over the range tested.

Parametric Models and Process Map for Alternating Current Square-Waveform Welding of Heat-Resistant Steel

The demand for efficient processes through a comprehensive understanding and optimization of welding conditions continues to grow in the manufacturing industry. This study involves heat-resistant 2.25 Cr-1 Mo V-groove steel welding using the square-waveform alternating cur-rent. Experiments were conducted to build the relationship between input variables—such as current, frequency, electrode negativity ratio, and welding speed—and process performance, such as penetration, bay area, deposition rate, melting efficiency, percentage dilution, flux–wire ratio, and heat input. The process was analyzed in light of the defect-free high-deposition weld groove weld, the sensitivity to process parameters, and the optimization and development of the process map. The study proposes an innovative approach to reducing the cost and time of optimizing the one-pass-each-layer V-groove welding process using bead-on-plate welds. Square waveform welding creates a metallurgical notch in the form of a bay at the fusion boundary that can be minimized by selecting appropriate welding conditions. The square waveform submerged arc welding is more sensitive towards changes in current and welding speed than the frequency and electrode negativity ratio; however, the electrode negativity ratio and frequency are minor but helpful parameters to achieve optimal results. The proximity of the planned and experimental results to within 3% confirms the validity of the proposed approach. The investigation shows that 90% of the maximum deposition rate is possible for one-pass-each-layer V-groove welds within heat input and weld width constraints.

Assessment of Corrosive Behaviour and Microstructure Characterization of Hybrid Friction Stir Welded Martensitic Stainless Steel

This study examined the effect of induction heating on the microstructure and corrosion characteristics of hybrid friction stir welded AISI 410 stainless steel. Five joints have been produced with different friction stir welding parameters like welding speed, spindle speed, plunge depth, and induction power. Their microstructures were evaluated using a scanning electron microscope, and chemical composition was examined using energy-dispersive X-ray spectroscopy (EDX). The rate of corrosion was found out via the weight loss method in a 1 M HCL solution. The hybrid friction stir welding method used for this work is induction assisted friction stir welding; the results show that this method could produce sound AISI 410 stainless steel Joints. The experiment results show that the joint made at a spindle speed of 1150 rpm, welding speed 40 mm/min, plunge depth 0.5 mm, and in-situ heat by induction 480°C show a better corrosion resistance property with a fine grain structure.

Experimental investigation and optimization of mechanical properties on combination of higher and lower strength of aluminum alloys

Friction stir welding is a high potential technology for joining similar and dissimilar aluminum materials, utilized extensively in aerospace and automotive industrial applications to eradicate the problems like hot cracking, porosity, element loss, etc. due to the fusion welding process. This Research addresses the joining of two dissimilar materials of AA 5754 – H32 and AA 8090T6511 – Al-Li and their mechanical properties analysis with the effects of friction stir welding process parameters like tool rotational speed, welding speed and axial load on weld nugget zone formation quality. The significant roles of different tool pin profiles are also emphasized. A mathematical modeling equation was formed by using regression analysis to optimize the process parameter and found the best tool pin profile for defect-free weld nugget zone and higher tensile and hardness properties. This research also portrays the contribution of various pin profiles and each process parameter on the ultimate tensile strength by response surface methodology. The results indicate that the defect-free weld joints are observed with 1800 r/min of rotational speed, welding speed of 15 mm min−1 and 8.5 kN of axial load with hexagonal pin profile.