In the TIG-MIG Hybrid welding, higher weld efficiency and better weld quality are obtained with respect to each individual TIG and MIG welding methods. Moreover, in this method, the MIG arc is more stable in pure argon shielding gas. Therefore, in this study, the influence of TIG-MIG Hybrid welding parameters on the welds appearance quality and welds depth to width ratio of a 316L austenitic stainless steel was investigated using optimum parameters of Taguchi design of experiments (DOE). Microstructure of the heat affected zone (HAZ) obtained from the Hybrid welding was compared with those of each individual MIG and TIG welding techniques under equal heat-input condition. The results indicated that the most important parameter in the Hybrid method to obtain the best appearance quality and the highest depth to width ratio is the distance between the two arcs. The MIG and TIG currents are the next influencing parameters. The width of HAZ and the size of constituent grains in Hybrid welding with optimum parameter, were smaller than those of each individual TIG and MIG processes due to the higher associated cooling rate in the Hybrid welding technique.

Hybrid laser-arc welding is a new welding process which has received particular attention in various industries because of its technological and economic advantages. This process combines a laser beam and an electric arc to incorporate the advantages of both laser and arc welding processes. The main goal of this paper is to evaluate the performance and ability of Hybrid Nd: YAG laser-TIG welding compared to lone laser welding process for welding of aluminum foam sandwich (AFS) panels of AA6082. To this aim, a set of experiments for both laser and Hybrid laser-TIG welding were done to investigate the effects of welding parameters including laser power, arc current and welding speed on weld dimensions.Then, appropriate welding parameters for the laser and Hybrid laser-TIG welding of AFS panels were calculated by statistical analysis. The results show that laser power threshold for creating the keyhole was less in Hybrid laser-TIG welding than lone laser welding. Moreover, increasing the laser power and decreasing the welding speed result in increasing both the weld depth and width. But, with increasing the arc current, the weld depth remains almost unchanged and only the weld width increases.Comparing the laser and Hybrid laser-TIG results show that adding a 100 A arc to a 2000 W laser source can increase the welding speed from 2 to 3 m/min which proves the high ability and efficiency of Hybrid laser-TIG welding process.

Rosa Hybrida is a perennial plant that after cut off head of the stem, lateral buds become free from apical dominance and begin to growth. In each new period of growth, new and young leaves can be formed. The four leaf samples were numbered from apex to base, showing young to mature leaf stages and some biochemical pigment markers changes were studied. The results suggest that during maturation, in addition to morphological differences, some physiological and biochemical markers are change. Data showed age dependent increase in the amount of pigments such as chlorophylls and carotenoids to reach the stage of leaf maturity to improve the leaf photosynthetic system efficiency. Gradually reducing in content of phenolic compounds, anthocyanins and flavonoids suggest reduction on oxidative damage.

Today, the demand for joining dissimilar metals of aluminium and steel to reduce the vehicle weight in the automotive, aerospace and shipbuilding industries has witnessed rapid growth. In the present study, 5083 aluminum alloy was joined to galvanized steel and plain carbon steel with 4043 and 4047 filler metals by using the welding-brazing Hybrid method. The brittle intermetallic compound (IMCs) layer formed in the interface of steel-weld seam was found to have significant influence on the joint strength. The results also indicated that increasing heat input enhanced the thickness of IMCs layer. The thickness of IMCs layers, as measured from microstructural images, was in range of 2-6 mm. Further, the results obtained from microstructural observation showed that with equal weld heat input, the thickness of IMCs layer for the joint produced with 4047 filler metal was approximately half of that obtained for the joint produced with 4043 filler metal. The highest mechanical resistance (of about 170 MPa) was obtained for aluminum to galvanized steel joint with 4047 filler metal. Moreover, in this joint, the failures occurred in the welded seam and for aluminum to plain carbon steel joint, it was in the interface of steel-weld seam. The results obtained by Energy dispersive x-ray spectrometry analysis of IMCs layer for aluminum to galvanized steel joint showed the presence of the FeAl3 intermetallic compound. This was confirmed by x-ray diffraction analysis of the fracture plane.

Welded tubular joints are widely used in various industry structures for high efficiency subjected to pressure, bending and twisting. Welded structures are the main parts of structures, buildings, bridges, gas pipes, pressure vessels and power transmission equipment in the ship building, construction, oil, gas, petrochemical industries and power plants. A sample of pipe-welded joints is a X-tubular joint that has been investigated in this study. The main objective of the present work is to investigate the heat transfer and residual stress caused by the three-stage welding process in Xtubular joint made of St52 using Simufact welding software. The welding process involves three welding steps using arc welding. The finite element model contains the thermal and mechanical properties of base metal and welding metal as a function of temperature. Also, advanced modeling tools such as mesh adaptation during the process and meshing compatible with the welding site, the birth and death technique of the element and the source of heat transfer have been used. welding simulation showed that significant residual stresses were created in the joint after welding. Comparison of the results shows that the numerical results and empirical measurements are in good agreement with each other and the existing model can provide a good prediction of temperature distribution and stress control in this welding process.

In the present study, 5083 aluminium alloy sheets by tungsten inert gas welding --brazing were joined to galvanized steel sheets with 4043 and 4047 filler wires. The amount of the weld heat and filler metal type influence the mechanical and microstructural properties of the resultant joint. The results obtained from microstructural observation showed that with equal weld heat input the thickness of brittle intermetallic compound layer for the joint produced with 4047 filler metal was approximately half of that for joint produced with 4043 filler metal. Energy dispersive x- ray spectrometry analysis results showed that the IMCs layer formed in interface of steel-weld seam consisted of Fe (Al, Si) 3 phase in side of steel and Al7.3Fe1.7 Si phase in side of welded seam. It was found that the joint produced with 4047 filler metal exhibit ed higher mechanical resistance of 170 MPa than that produced with 4043 of 120 MPa. The results of x-ray diffraction analysis conducted on the fracture plane showed the presence of Al0.5Fe3Si0.5 phase. Moreover, for joints produced with 4047 filler metal, the FeSi2 phase created from enriching of Si atoms in IMCs layer was seen.

In this study, thermo-mechanical stability of two-pass constrained groove pressing (CGP) AA1050 sheets towards friction stir welding (FSW) employing Hybrid powder (%50vol. micrometric graphite powder+%50vol. α-Al2O3 nanoparticles) was investigated by examining its microstructural evolutions and mechanical properties. FSW was carried out via different process variables in order to reach the highest ultimate mechanical properties of joints. The welding variables employed in this study were single-pass and multi-pass FSW, and different rotation speed to traverse speed ratios (ω/v) were. In order to appraise the powder effect on mechanical properties in the fabricated Hybrid metal matrix composite (HMMC), some CGPed sheets were also welded with no powder. Besides optical microscopy and field emission scanning electron microscopy (FESEM) observations, Vickers microhardness and transverse tensile tests were conducted to examine mechanical properties of the weld zone. It was revealed that the effect of graphite powder as a solid lubricant was substantially influenced by the welding variables. More precisely, by employing graphite powder during the FSW, the peak temperature decreased to 224 ℃, while the peak temperature of 489 ℃ was resulted by welding without any powder. Thus, the thermo-mechanical stability of CGPed aluminum and their mechanical properties were enhanced. On the other hand, graphite powder can be responsible for mechanical properties drop due to deteriorating material flow. In addition, different strengthening mechanisms, including grain boundary Zener-pinning and particulate stimulated nucleation (PSN) mechanism, were provided and governed by both powders. However, increasing the ω/v ratio was a practical approach to obtain uniform powder distribution, and consequently, to attain ultimate mechanical properties. Moreover, weld soundness was perceived to be achievable by increasing the number of FSW passes due to eliminating the cavities and improved material flow, resulting in an ultimate tensile strength of 101 MPa, as an optimum efficiency of ~ %80, in three-pass FSW at ω/v=70.

Rose is considered as one of the most popular and important ornamental plants in the world. During the last decade, tissue culture, micropropagation as well as genetic engineering have prevailed in rose production industry. Gene transfer to embryogenic callus, derived from different types of explants is currently one of the most popular methods of improvement of rose cultivars, presented in particular as cut flower with such novel characteristics as blue color. An efficient tissue culture procedure covering high frequency embryogenic callus induction and plant regeneration is pre-requisite for every successful genetic engineering program. An efficient method for embryogenic callus induction from growing nodal stem segments on MS medium followed by a selection of appropriate young leaflets is hereby reported. MS medium complemented with 2 mg/L 2, 4-D, and 0.5 mg/L NAA as wekk as medium B5 complemented with 0.5 mg/L 2, 4-D and 2.5 mg/L NAA plus 0.5mg/L kinetin were used for callus induction. Cali were then subcultured in MS medium with higher levels of hormone (3 mg/L 2, 4-D and 0.5 mg/LNAA) to develop suitable size and shape embryos. This was followed by transferring the calli onto an MS medium complemented with 8 hormonal treatments. MS medium along with 1 mg/L of TDZ resulted in a highest number of embryos. High frequency of shoot development from mature somatic embryo and subsequent plant regeneration were obtained on a medium containing 3 mg/L of BAP. Shoots were rooted on MS medium supplemented with three various hormonal treatments, and there were no significant differences observed between treatments.