The purpose of this research is to analyze the mechanical properties and corrosion resistance of spot welding of stainless steels AISI 316L using the process of resistance spot welding varying welding parameters with three level for each of welding parameter; welding current (A.), electrode Pressure (bar), squeeze time (s.), and welding time (s.). The welding current was (4500, 5500 and 6500) A, the electrode Pressure was (20, 30 and 40) bar, the squeeze time was (0.6, 0.8 and 1) Sec., and the welding time was (0.3, 0.6 and 0.9) Sec. The specimens were inspected by a tensile-shear test, corrosion test and the inspection of scanning electron microscope (SEM). The technique of design of the experiments (DOE) was utilized to examine the influence of the welding process parameters on the joint tensile-shear force. The results were analyzed by the DOE method to determine the optimum tensile-shear force, where can be obtained by utilizing the welding parameters by welding current 5500A, electrode pressure of 30 bar, squeeze time 0.8s., and welding time of 0.3s. The examination of SEM indicated that the increment of welding current and electrode pressure leads to increment pitting and corrosion rate.

Swirl combustors have proven to be effective flame stabilisers over a wide range of operation conditions thanks to the formation of well-known swirl coherent structures. However, their employment for lean premixed combustion modes while introducing alternative fuels such as high hydrogenated blends results in many combustion instabilities. Under these conditions, flame flashback is considered one of the major instability problems that have the potential of causing considerable damage to combustion systems hardware in addition to the significant increase in pollutant levels. Combustion Induced Vortex Breakdown is considered a very particular mode of flashback instability in swirling flows as this type of flashback occurs even when the fresh mixture velocity is higher than the flame speed, a consequence of the interaction between swirl structures and swirl burner geometries. Improvements in burner geometries and manipulation of swirling flows can increase resistance against this type of flashback. However, increasing resistance against Combustion Induced Vortex Breakdown can lead to augmentation in the propensity of another flashback mechanism, Boundary Layer Flashback. Thus, this paper presents an experimental approach of a combination of techniques that increase Combustion Induced Vortex Breakdown resistance, i.e. by repositioning a central injector and using central air injection, while simultaneously avoiding Boundary Layer Flashback, i.e. by changing the wall boundary layer characteristics using microsurfaces on the nozzle wall. Results show that using these techniques together has promising potentials regarding wider stable operation for swirl combustors, enabling them to burn a broader variety of fuel blends safely, while informing developers of the improvements obtained with the combined techniques.

Conventional quenching versus ZnO-NP emulsion and heat treatments for medium carbon steel (CK45) has been carried out in laboratory environment condition. For comparison, the mechanical properties of CK45 and microstructure were examined. The main parameter focused in this work was the concentration of ZnO-NP in deionized water. Thus, emulsion represents a quenching medium for CK45 specimens. Optical microscope analysis for CK45 microstructure, hardness and tensile test for all specimens were done to evaluate the role of nano ZnO additives as quenching media at different concentration. Experimental results reveal that the addition of nanoparticles to the base fluid (water) astonishingly enhanced some mechanical properties as tensile strength and yield stress. 2wt.% of ZnO-NP raised the yield 14.8% and the UTS by 16.9%.

This work deals with determination of optimum conditions of direct diffusion bonding welding of austenitic stainlesssteel type AISI 304L with Oxygen Free High Conductivity (OFHC) pure copper grade (C10200) in vacuum atmosphere of (1.5 *10-5 mbr.). Mini tab (response surface) was applied for optimizing the influence of diffusion bonding parameters (temperature, time and applied load) on the bonding joints characteristics and the empirical relationship was evaluated which represents the effect of each parameter of the process. The yield strength of diffusion bonded joint was equal to 153 MPa and the efficiency of joint was equal to 66.5% as compared with hard drawn copper. The diffusion zone reveals high microhardness than copper side due to solid solution phase formation of (CuNi). The failure of bonded joints always occurred on the copper side and fracture surface morphologies are characterized by ductile failure mode with dimple structure. Optimum bonding conditions were observed at temperature of 650 ◦C, duration time of 45 min. and the applied stress of 30 MPa. The maximum depth of diffuse copper in stainless steel side was equal 11.80 µm.

Thermoset polymer has considerable useful properties in structure, energy and marine industries. Polyepoxide or epoxy is widely used in composite matrix materials, and therefore, the adhesion between the reinforcement and the matrix is crucial. In order to enhance the adhesion conceptually, single steel fiber reinforcement polymer (SRP) was used in a polyepoxide matrix. The fiber pull-out test (FPO) was used to evaluate the adhesion properties by using thin films of copper for the wire fiber. For comparison, the results of the FPO for uncoated fiber with an average surface roughness of Ra = 0.03 μm were obtained. The results show an increase in toughness and strength compared with uncoated rougher fiber. The results of scanning electron microscopy (SEM) clearly show that copper debonding requires an interface fracture energy and there is a possibility of copper diffusion, which is confirmed by point EDX. The energy absorption of the wire thin film copper increased by 42%, and the maximum force pull-out increased by 14%. The modeling of the current study shows the crack initiation starts from the side of the fiber pull-out direction, and the maximum stress component was just near the free non-encompassed wire.